Revert "Only draw lines in one direction"

This reverts commit cd32e03a2d.

CMakeLists.txt

@@ -66,6 +66,7 @@ set(engine_SRCS # Except main.cpp.
     src/MeshGroup.cpp
     src/multiVolumes.cpp
     src/pathOrderOptimizer.cpp
+    src/Preheat.cpp
     src/PrimeTower.cpp
     src/raft.cpp
     src/skin.cpp
@@ -84,9 +85,13 @@ set(engine_SRCS # Except main.cpp.
     src/infill/ZigzagConnectorProcessorDisconnectedEndPieces.cpp
     src/infill/ZigzagConnectorProcessorEndPieces.cpp
     src/infill/ZigzagConnectorProcessorNoEndPieces.cpp
+    src/infill/SubDivCube.cpp
 
     src/pathPlanning/Comb.cpp
+    src/pathPlanning/GCodePath.cpp
     src/pathPlanning/LinePolygonsCrossings.cpp
+    src/pathPlanning/NozzleTempInsert.cpp
+    src/pathPlanning/TimeMaterialEstimates.cpp
 
     src/progress/Progress.cpp
     src/progress/ProgressStageEstimator.cpp

Doxyfile

@@ -832,7 +832,7 @@ EXAMPLE_RECURSIVE      = NO
 # that contain images that are to be included in the documentation (see the
 # \image command).
 
-IMAGE_PATH             = documentation/assets
+IMAGE_PATH             = docs/assets
 
 # The INPUT_FILTER tag can be used to specify a program that doxygen should
 # invoke to filter for each input file. Doxygen will invoke the filter program

README.md

@@ -31,6 +31,7 @@ CMake compilation:
 4. ```$ make```
 
 Project files generation:
+
 1. Navigate to the CuraEngine directory and execute the following commands
 2. ```cmake . -G "CodeBlocks - Unix Makefiles"```
 3. (for a list of supported IDE's see http://www.cmake.org/Wiki/CMake_Generator_Specific_Information#Code::Blocks_Generator)

docs/mainpage.md

@@ -7,4 +7,4 @@ This is the documentation for CuraEngine, the back-end slicer of Cura.
 
 [Glossary](documentation/glossary.md)
 
-[Code Conventions](documentation/code_conventions.md)
+[Code Conventions](https://github.com/Ultimaker/Meta/blob/master/code_conventions.md)

documentation/Link_to_index.html

@@ -1 +0,0 @@
-html/index.html

libs/clipper/clipper.hpp

@@ -44,7 +44,7 @@
 //#define use_xyz
 
 //use_lines: Enables line clipping. Adds a very minor cost to performance.
-//#define use_lines
+#define use_lines
   
 //use_deprecated: Enables temporary support for the obsolete functions
 //#define use_deprecated  

resources/command_line_settings.def.json

@@ -1,58 +0,0 @@
-{
-    "version": 2,
-    "name": "Command line setting defaults CuraEngine",
-    "metadata":
-    {
-        "author": "Ultimaker B.V."
-    },
-    "settings": {
-        "command_line_settings": {
-            "label": "Command Line Settings",
-            "type": "category",
-            "children": {
-                "center_object": {
-                    "description": "Whether to center the object on the middle of the build platform (0,0), instead of using the coordinate system in which the object was saved.",
-                    "type": "bool",
-                    "label": "Center object",
-                    "default_value": true
-                },
-                "machine_print_temp_wait": {
-                    "description": "Whether to wait for the nozzle temperature to be reached when preheating the nozzles at the start of the gcode.",
-                    "type": "bool",
-                    "label": "Machine print temp wait",
-                    "default_value": true
-                },
-                "mesh_position_x": {
-                    "description": "Offset applied to the object in the x direction.",
-                    "type": "float",
-                    "label": "Mesh position x",
-                    "default_value": 0
-                },
-                "mesh_position_y": {
-                    "description": "Offset applied to the object in the y direction.",
-                    "type": "float",
-                    "label": "Mesh position y",
-                    "default_value": 0
-                },
-                "mesh_position_z": {
-                    "description": "Offset applied to the object in the z direction. With this you can perform what was used to call 'Object Sink'.",
-                    "type": "float",
-                    "label": "Mesh position z",
-                    "default_value": 0
-                },
-                "mesh_rotation_matrix": {
-                    "label": "Mesh Rotation Matrix",
-                    "description": "Transformation matrix to be applied to the model when loading it from file.",
-                    "type": "string",
-                    "default_value": "[[1,0,0], [0,1,0], [0,0,1]]"
-                },
-                "prime_tower_dir_outward": {
-                    "description": "Whether to start printing in the middle of the prime tower and end up at the perimeter, or the other way around. This is only used for certain types of prime tower.",
-                    "type": "bool",
-                    "label": "Prime tower direction outward",
-                    "default_value": false
-                }
-            }
-        }
-    }
-}

src/FanSpeedLayerTime.h

@@ -11,6 +11,7 @@ struct FanSpeedLayerTimeSettings
 public:
     double cool_min_layer_time;
     double cool_min_layer_time_fan_speed_max;
+    double cool_fan_speed_0;
     double cool_fan_speed_min;
     double cool_fan_speed_max;
     double cool_min_speed;

src/FffGcodeWriter.cpp

@@ -6,6 +6,7 @@
 #include "FffProcessor.h"
 #include "progress/Progress.h"
 #include "wallOverlap.h"
+#include "utils/orderOptimizer.h"
 
 namespace cura
 {
@@ -18,13 +19,13 @@ void FffGcodeWriter::writeGCode(SliceDataStorage& storage, TimeKeeper& time_keep
     if (FffProcessor::getInstance()->getMeshgroupNr() == 0)
     { // first meshgroup
         gcode.resetTotalPrintTimeAndFilament();
-        gcode.setInitialTemps(*storage.meshgroup);
+        gcode.setInitialTemps(*storage.meshgroup, getStartExtruder(storage));
     }
 
     // set the initial extruder of this meshgroup
     if (FffProcessor::getInstance()->getMeshgroupNr() == 0)
     { // first meshgroup
-        current_extruder_planned = getSettingAsIndex("adhesion_extruder_nr");
+        current_extruder_planned = getStartExtruder(storage);
     }
     else
     {
@@ -54,7 +55,8 @@ void FffGcodeWriter::writeGCode(SliceDataStorage& storage, TimeKeeper& time_keep
     
     if (FffProcessor::getInstance()->getMeshgroupNr() == 0)
     {
-        processStartingCode(storage);
+        unsigned int start_extruder_nr = getStartExtruder(storage);
+        processStartingCode(storage, start_extruder_nr);
     }
     else
     {
@@ -80,6 +82,15 @@ void FffGcodeWriter::writeGCode(SliceDataStorage& storage, TimeKeeper& time_keep
         }
     }
 
+    { // calculate the mesh order for each extruder
+        int extruder_count = storage.meshgroup->getExtruderCount();
+        mesh_order_per_extruder.reserve(extruder_count);
+        for (int extruder_nr = 0; extruder_nr < extruder_count; extruder_nr++)
+        {
+            mesh_order_per_extruder.push_back(calculateMeshOrder(storage, extruder_nr));
+        }
+    }
+
     for(unsigned int layer_nr=0; layer_nr<total_layers; layer_nr++)
     {
         processLayer(storage, layer_nr, total_layers);
@@ -93,7 +104,7 @@ void FffGcodeWriter::writeGCode(SliceDataStorage& storage, TimeKeeper& time_keep
     layer_plan_buffer.flush();
 
     constexpr bool force = true;
-    gcode.writeRetraction(&storage.retraction_config_per_extruder[gcode.getExtruderNr()], force); // retract after finishing each meshgroup
+    gcode.writeRetraction(storage.retraction_config_per_extruder[gcode.getExtruderNr()], force); // retract after finishing each meshgroup
 }
 
 void FffGcodeWriter::setConfigFanSpeedLayerTime(SliceDataStorage& storage)
@@ -105,12 +116,14 @@ void FffGcodeWriter::setConfigFanSpeedLayerTime(SliceDataStorage& storage)
         ExtruderTrain* train = storage.meshgroup->getExtruderTrain(extr);
         fan_speed_layer_time_settings.cool_min_layer_time = train->getSettingInSeconds("cool_min_layer_time");
         fan_speed_layer_time_settings.cool_min_layer_time_fan_speed_max = train->getSettingInSeconds("cool_min_layer_time_fan_speed_max");
+        fan_speed_layer_time_settings.cool_fan_speed_0 = train->getSettingInPercentage("cool_fan_speed_0");
         fan_speed_layer_time_settings.cool_fan_speed_min = train->getSettingInPercentage("cool_fan_speed_min");
         fan_speed_layer_time_settings.cool_fan_speed_max = train->getSettingInPercentage("cool_fan_speed_max");
         fan_speed_layer_time_settings.cool_min_speed = train->getSettingInMillimetersPerSecond("cool_min_speed");
         fan_speed_layer_time_settings.cool_fan_full_layer = train->getSettingAsLayerNumber("cool_fan_full_layer");
         if (!train->getSettingBoolean("cool_fan_enabled"))
         {
+            fan_speed_layer_time_settings.cool_fan_speed_0 = 0;
             fan_speed_layer_time_settings.cool_fan_speed_min = 0;
             fan_speed_layer_time_settings.cool_fan_speed_max = 0;
         }
@@ -191,7 +204,26 @@ void FffGcodeWriter::initConfigs(SliceDataStorage& storage)
     storage.primeTower.initConfigs(storage.meshgroup);
 }
 
-void FffGcodeWriter::processStartingCode(SliceDataStorage& storage)
+unsigned int FffGcodeWriter::getStartExtruder(SliceDataStorage& storage)
+{
+    int start_extruder_nr = getSettingAsIndex("adhesion_extruder_nr");
+    if (getSettingAsPlatformAdhesion("adhesion_type") == EPlatformAdhesion::NONE)
+    {
+        std::vector<bool> extruder_is_used = storage.getExtrudersUsed();
+        for (unsigned int extruder_nr = 0; extruder_nr < extruder_is_used.size(); extruder_nr++)
+        {
+            start_extruder_nr = extruder_nr;
+            if (extruder_is_used[extruder_nr])
+            {
+                break;
+            }
+        }
+    }
+    assert(start_extruder_nr >= 0 && start_extruder_nr < storage.meshgroup->getExtruderCount() && "start_extruder_nr must be a valid extruder");
+    return start_extruder_nr;
+}
+
+void FffGcodeWriter::processStartingCode(SliceDataStorage& storage, const unsigned int start_extruder_nr)
 {
     if (!CommandSocket::isInstantiated())
     {
@@ -199,17 +231,15 @@ void FffGcodeWriter::processStartingCode(SliceDataStorage& storage)
         gcode.writeCode(prefix.c_str());
     }
 
-    int start_extruder_nr = getSettingAsIndex("adhesion_extruder_nr");
-
     gcode.writeComment("Generated with Cura_SteamEngine " VERSION);
 
     if (gcode.getFlavor() != EGCodeFlavor::ULTIGCODE && gcode.getFlavor() != EGCodeFlavor::GRIFFIN)
     {
         if (getSettingBoolean("material_bed_temp_prepend")) 
         {
-            if (getSettingBoolean("machine_heated_bed") && getSettingInDegreeCelsius("material_bed_temperature") > 0)
+            if (getSettingBoolean("machine_heated_bed") && getSettingInDegreeCelsius("material_bed_temperature_layer_0") != 0)
             {
-                gcode.writeBedTemperatureCommand(getSettingInDegreeCelsius("material_bed_temperature"), getSettingBoolean("material_bed_temp_wait"));
+                gcode.writeBedTemperatureCommand(getSettingInDegreeCelsius("material_bed_temperature_layer_0"), getSettingBoolean("material_bed_temp_wait"));
             }
         }
 
@@ -217,15 +247,19 @@ void FffGcodeWriter::processStartingCode(SliceDataStorage& storage)
         {
             for (int extruder_nr = 0; extruder_nr < storage.getSettingAsCount("machine_extruder_count"); extruder_nr++)
             {
-                double print_temp = storage.meshgroup->getExtruderTrain(extruder_nr)->getSettingInDegreeCelsius("material_print_temperature");
-                gcode.writeTemperatureCommand(extruder_nr, print_temp);
+                ExtruderTrain& train = *storage.meshgroup->getExtruderTrain(extruder_nr);
+                double print_temp_0 = train.getSettingInDegreeCelsius("material_print_temperature_layer_0");
+                double print_temp_here = (print_temp_0 != 0)? print_temp_0 : train.getSettingInDegreeCelsius("material_print_temperature");
+                gcode.writeTemperatureCommand(extruder_nr, print_temp_here);
             }
             if (getSettingBoolean("material_print_temp_wait")) 
             {
                 for (int extruder_nr = 0; extruder_nr < storage.getSettingAsCount("machine_extruder_count"); extruder_nr++)
                 {
-                    double print_temp = storage.meshgroup->getExtruderTrain(extruder_nr)->getSettingInDegreeCelsius("material_print_temperature");
-                    gcode.writeTemperatureCommand(extruder_nr, print_temp, true);
+                    ExtruderTrain& train = *storage.meshgroup->getExtruderTrain(extruder_nr);
+                    double print_temp_0 = train.getSettingInDegreeCelsius("material_print_temperature_layer_0");
+                    double print_temp_here = (print_temp_0 != 0)? print_temp_0 : train.getSettingInDegreeCelsius("material_print_temperature");
+                    gcode.writeTemperatureCommand(extruder_nr, print_temp_here, true);
                 }
             }
         }
@@ -247,18 +281,26 @@ void FffGcodeWriter::processStartingCode(SliceDataStorage& storage)
         gcode.startExtruder(start_extruder_nr);
         ExtruderTrain& train = *storage.meshgroup->getExtruderTrain(start_extruder_nr);
         constexpr bool wait = true;
-        gcode.writeTemperatureCommand(start_extruder_nr, train.getSettingInDegreeCelsius("material_print_temperature"), wait);
+        double print_temp_0 = train.getSettingInDegreeCelsius("material_print_temperature_layer_0");
+        double print_temp_here = (print_temp_0 != 0)? print_temp_0 : train.getSettingInDegreeCelsius("material_print_temperature");
+        gcode.writeTemperatureCommand(start_extruder_nr, print_temp_here, wait);
         gcode.writePrimeTrain(train.getSettingInMillimetersPerSecond("speed_travel"));
+        extruder_prime_is_planned[start_extruder_nr] = true;
         RetractionConfig& retraction_config = storage.retraction_config_per_extruder[start_extruder_nr];
-        gcode.writeRetraction(&retraction_config);
+        gcode.writeRetraction(retraction_config);
     }
 }
 
 void FffGcodeWriter::processNextMeshGroupCode(SliceDataStorage& storage)
 {
     gcode.writeFanCommand(0);
+
+    bool wait = true;
+    gcode.writeBedTemperatureCommand(storage.getSettingInDegreeCelsius("material_bed_temperature_layer_0"), wait);
+
     gcode.resetExtrusionValue();
     CommandSocket::setSendCurrentPosition(gcode.getPositionXY());
+
     gcode.setZ(max_object_height + 5000);
     gcode.writeMove(gcode.getPositionXY(), storage.meshgroup->getExtruderTrain(gcode.getExtruderNr())->getSettingInMillimetersPerSecond("speed_travel"), 0);
     last_position_planned = Point(storage.model_min.x, storage.model_min.y);
@@ -302,10 +344,8 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         GCodePlanner& gcode_layer = layer_plan_buffer.emplace_back(storage, layer_nr, z, layer_height, last_position_planned, current_extruder_planned, is_inside_mesh_layer_part, fan_speed_layer_time_settings_per_extruder, combing_mode, comb_offset, train->getSettingBoolean("travel_avoid_other_parts"), train->getSettingInMicrons("travel_avoid_distance"));
         gcode_layer.setIsInside(true);
 
-        if (getSettingAsIndex("adhesion_extruder_nr") > 0)
-        {
-            gcode_layer.setExtruder(extruder_nr);
-        }
+        gcode_layer.setExtruder(extruder_nr);
+
         if (CommandSocket::isInstantiated())
         {
             CommandSocket::getInstance()->sendOptimizedLayerInfo(layer_nr, z, layer_height);
@@ -320,6 +360,11 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         infill_comp.generate(raft_polygons, raftLines);
         gcode_layer.addLinesByOptimizer(raftLines, &storage.raft_base_config, SpaceFillType::Lines);
 
+        if (getExtrudersNeedPrimeDuringFirstLayer())
+        {
+            ensureAllExtrudersArePrimed(storage, gcode_layer, layer_nr);
+        }
+
         last_position_planned = gcode_layer.getLastPosition();
         current_extruder_planned = gcode_layer.getExtruder();
         is_inside_mesh_layer_part = gcode_layer.getIsInsideMesh();
@@ -336,11 +381,13 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         GCodePlanner& gcode_layer = layer_plan_buffer.emplace_back(storage, layer_nr, z, layer_height, last_position_planned, current_extruder_planned, is_inside_mesh_layer_part, fan_speed_layer_time_settings_per_extruder, combing_mode, comb_offset, train->getSettingBoolean("travel_avoid_other_parts"), train->getSettingInMicrons("travel_avoid_distance"));
         gcode_layer.setIsInside(true);
 
+        gcode_layer.setExtruder(extruder_nr); // reset to extruder number, because we might have primed in the last layer
+
         if (CommandSocket::isInstantiated())
         {
             CommandSocket::getInstance()->sendOptimizedLayerInfo(layer_nr, z, layer_height);
         }
-        
+
         Polygons raftLines;
         int offset_from_poly_outline = 0;
         double fill_angle = train->getSettingAsCount("raft_surface_layers") > 0 ? 45 : 90;
@@ -423,7 +470,7 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
     }
 
     bool avoid_other_parts = false;
-    int avoid_distance = 0; // minimal avoid distance is zero
+    coord_t avoid_distance = 0; // minimal avoid distance is zero
     for (int extr_nr = 0; extr_nr < storage.meshgroup->getExtruderCount(); extr_nr++)
     {
         if (gcode.getExtruderIsUsed(extr_nr))
@@ -438,7 +485,7 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
         }
     }
 
-    int max_inner_wall_width = 0;
+    coord_t max_inner_wall_width = 0;
     for (SettingsBaseVirtual& mesh_settings : storage.meshes)
     {
         max_inner_wall_width = std::max(max_inner_wall_width, mesh_settings.getSettingInMicrons((mesh_settings.getSettingAsCount("wall_line_count") > 1) ? "wall_line_width_x" : "wall_line_width_0")); 
@@ -451,63 +498,86 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
 
     if (include_helper_parts && layer_nr == 0)
     { // process the skirt or the brim of the starting extruder.
-        int extruder_nr = getSettingAsIndex("adhesion_extruder_nr");
+        int extruder_nr = gcode_layer.getExtruder();
         if (storage.skirt_brim[extruder_nr].size() > 0)
         {
-            gcode_layer.setExtruder(extruder_nr);
             processSkirtBrim(storage, gcode_layer, extruder_nr);
         }
     }
-
-    int extruder_nr_before = gcode_layer.getExtruder();
     if (include_helper_parts)
-    {
-        addSupportToGCode(storage, gcode_layer, std::max(0, layer_nr), extruder_nr_before, true);
-
+    { // handle shield(s) first in a layer so that chances are higher that the other nozzle is wiped (for the ooze shield)
         processOozeShield(storage, gcode_layer, std::max(0, layer_nr));
 
         processDraftShield(storage, gcode_layer, std::max(0, layer_nr));
     }
 
-    if (layer_nr >= 0)
+    int support_skin_extruder_nr = getSettingAsIndex("support_interface_extruder_nr");
+    int support_infill_extruder_nr = (layer_nr <= 0)? getSettingAsIndex("support_extruder_nr_layer_0") : getSettingAsIndex("support_infill_extruder_nr");
+
+    std::vector<int> extruder_order = calculateExtruderOrder(storage, gcode_layer.getExtruder());
+    for (int extruder_nr : extruder_order)
     {
-        //Figure out in which order to print the meshes, do this by looking at the current extruder and preferer the meshes that use that extruder.
-        std::vector<unsigned int> mesh_order = calculateMeshOrder(storage, gcode_layer.getExtruder());
-        for(unsigned int mesh_idx : mesh_order)
+        if (include_helper_parts
+            && (extruder_nr == support_infill_extruder_nr || extruder_nr == support_skin_extruder_nr))
         {
-            SliceMeshStorage* mesh = &storage.meshes[mesh_idx];
-            if (mesh->getSettingAsSurfaceMode("magic_mesh_surface_mode") == ESurfaceMode::SURFACE)
-            {
-                addMeshLayerToGCode_meshSurfaceMode(storage, mesh, gcode_layer, layer_nr);
+            addSupportToGCode(storage, gcode_layer, layer_nr, extruder_nr);
+        }
+
+        if (layer_nr >= 0)
+        {
+            std::vector<unsigned int>& mesh_order = mesh_order_per_extruder[extruder_nr];
+            unsigned int mesh_order_idx_starting_mesh = 0;
+            { // calculate mesh_order_idx_starting_mesh
+                Point layer_start_position = last_position_planned;
+                if (storage.getSettingBoolean("start_layers_at_same_position"))
+                {
+                    layer_start_position = Point(storage.getSettingInMicrons("layer_start_x"), storage.getSettingInMicrons("layer_start_y"));
+                }
+                coord_t best_dist2 = std::numeric_limits<coord_t>::max();
+                for (unsigned int mesh_order_idx = 0; mesh_order_idx < mesh_order.size(); mesh_order_idx++)
+                {
+                    unsigned int mesh_idx = mesh_order[mesh_order_idx];
+                    SliceMeshStorage& mesh = storage.meshes[mesh_idx];
+                    for (SliceLayerPart& part : mesh.layers[layer_nr].parts)
+                    {
+                        Point middle = (part.boundaryBox.min + part.boundaryBox.max) / 2;
+                        coord_t dist2 = vSize2(middle - layer_start_position);
+                        if (dist2 < best_dist2)
+                        {
+                            best_dist2 = dist2;
+                            mesh_order_idx_starting_mesh = mesh_order_idx;
+                        }
+                    }
+                }
             }
-            else
+
+            for (unsigned int mesh_iterator_idx = 0; mesh_iterator_idx < mesh_order.size(); mesh_iterator_idx++)
             {
-                addMeshLayerToGCode(storage, mesh, gcode_layer, layer_nr);
+                unsigned int mesh_order_idx = (mesh_iterator_idx + mesh_order_idx_starting_mesh) % mesh_order.size();
+                unsigned int mesh_idx = mesh_order[mesh_order_idx];
+                SliceMeshStorage* mesh = &storage.meshes[mesh_idx];
+                if (mesh->getSettingAsSurfaceMode("magic_mesh_surface_mode") == ESurfaceMode::SURFACE)
+                {
+                    addMeshLayerToGCode_meshSurfaceMode(storage, mesh, gcode_layer, layer_nr);
+                }
+                else
+                {
+                    addMeshLayerToGCode(storage, mesh, gcode_layer, layer_nr);
+                }
             }
         }
     }
 
-    if (include_helper_parts)
+    if (layer_nr == 0 && getExtrudersNeedPrimeDuringFirstLayer())
     {
-        addSupportToGCode(storage, gcode_layer, std::max(0, layer_nr), extruder_nr_before, false);
-    }
-
-    if (include_helper_parts && layer_nr == 0)
-    { //Add skirt for all extruders which haven't primed the skirt or brim yet.
-        for (int extruder_nr = 0; extruder_nr < storage.meshgroup->getExtruderCount(); extruder_nr++)
-        {
-            if (gcode.getExtruderIsUsed(extruder_nr) && !skirt_brim_is_processed[extruder_nr] && storage.skirt_brim[extruder_nr].size() > 0)
-            {
-                setExtruder_addPrime(storage, gcode_layer, layer_nr, extruder_nr);
-            }
-        }
+        ensureAllExtrudersArePrimed(storage, gcode_layer, layer_nr);
     }
 
     if (include_helper_parts)
     { // add prime tower if it hasn't already been added
         // print the prime tower if it hasn't been printed yet
         int prev_extruder = gcode_layer.getExtruder(); // most likely the same extruder as we are extruding with now
-        addPrimeTower(storage, gcode_layer, std::max(0, layer_nr), prev_extruder);
+        addPrimeTower(storage, gcode_layer, layer_nr, prev_extruder);
     }
     
     last_position_planned = gcode_layer.getLastPosition();
@@ -517,6 +587,31 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
     gcode_layer.processFanSpeedAndMinimalLayerTime();
 }
 
+bool FffGcodeWriter::getExtrudersNeedPrimeDuringFirstLayer()
+{
+    switch(gcode.getFlavor())
+    {
+        case EGCodeFlavor::GRIFFIN:
+            return true;
+        default:
+            return false; // TODO: change this once priming for other firmware types is implemented
+    }
+}
+
+void FffGcodeWriter::ensureAllExtrudersArePrimed(SliceDataStorage& storage, GCodePlanner& gcode_layer, const int layer_nr)
+{
+    // Add prime for all extruders which haven't primed yet.
+
+    std::vector<bool> extruder_is_used = storage.getExtrudersUsed();
+    for (int extruder_nr = 0; extruder_nr < storage.meshgroup->getExtruderCount(); extruder_nr++)
+    {
+        if (extruder_is_used[extruder_nr] && !extruder_prime_is_planned[extruder_nr])
+        { // prime before the current gcode layer plan is written to gcode
+            setExtruder_addPrime(storage, gcode_layer, layer_nr, extruder_nr);
+        }
+    }
+}
+
 void FffGcodeWriter::processSkirtBrim(SliceDataStorage& storage, GCodePlanner& gcode_layer, unsigned int extruder_nr)
 {
     if (skirt_brim_is_processed[extruder_nr])
@@ -575,30 +670,44 @@ void FffGcodeWriter::processDraftShield(SliceDataStorage& storage, GCodePlanner&
     gcode_layer.addPolygonsByOptimizer(storage.draft_protection_shield, &storage.skirt_brim_config[0]); //TODO: Skirt and brim configuration index should correspond to draft shield extruder number.
 }
 
-std::vector<unsigned int> FffGcodeWriter::calculateMeshOrder(SliceDataStorage& storage, int current_extruder)
+std::vector<int> FffGcodeWriter::calculateExtruderOrder(SliceDataStorage& storage, int current_extruder)
 {
-    std::vector<unsigned int> ret;
-    std::list<unsigned int> add_list;
-    for(unsigned int mesh_idx = 0; mesh_idx < storage.meshes.size(); mesh_idx++)
-        add_list.push_back(mesh_idx);
-
-    int add_extruder_nr = current_extruder;
-    while(add_list.size() > 0)
+    int extruder_count = storage.getSettingAsCount("machine_extruder_count");
+    std::vector<int> ret;
+    ret.push_back(current_extruder);
+    for (int extruder_nr = 0; extruder_nr < extruder_count; extruder_nr++)
     {
-        for(auto add_it = add_list.begin(); add_it != add_list.end(); )
-        {
-            if (storage.meshes[*add_it].getSettingAsIndex("extruder_nr") == add_extruder_nr)
-            {
-                ret.push_back(*add_it);
-                add_it = add_list.erase(add_it);
-            } 
-            else 
-            {
-                ++add_it;
-            }
+        if (extruder_nr == current_extruder)
+        { // skip the current extruder, it's the one we started out planning
+            continue;
         }
-        if (add_list.size() > 0)
-            add_extruder_nr = storage.meshes[*add_list.begin()].getSettingAsIndex("extruder_nr");
+        ret.push_back(extruder_nr);
+    }
+    assert(ret.size() == (size_t)extruder_count && "All extruders must be planned, even if later it appears one wasn't used.");
+    return ret;
+}
+
+std::vector<unsigned int> FffGcodeWriter::calculateMeshOrder(SliceDataStorage& storage, int extruder_nr)
+{
+    OrderOptimizer<unsigned int> mesh_idx_order_optimizer;
+
+    for (unsigned int mesh_idx = 0; mesh_idx < storage.meshes.size(); mesh_idx++)
+    {
+        SliceMeshStorage& mesh = storage.meshes[mesh_idx];
+        if (mesh.getSettingAsIndex("extruder_nr") == extruder_nr)
+        {
+            Mesh& mesh_data = storage.meshgroup->meshes[mesh_idx];
+            Point3 middle = (mesh_data.getAABB().min + mesh_data.getAABB().max) / 2;
+            mesh_idx_order_optimizer.addItem(Point(middle.x, middle.y), mesh_idx);
+        }
+    }
+    std::list<unsigned int> mesh_indices_order = mesh_idx_order_optimizer.optimize();
+    std::vector<unsigned int> ret;
+    ret.reserve(mesh_indices_order.size());
+    for (unsigned int mesh_order_idx : mesh_indices_order)
+    {
+        const unsigned int mesh_idx = mesh_idx_order_optimizer.items[mesh_order_idx].second;
+        ret.push_back(mesh_idx);
     }
     return ret;
 }
@@ -609,7 +718,14 @@ void FffGcodeWriter::addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& stora
     {
         return;
     }
-    
+
+    if (mesh->getSettingBoolean("anti_overhang_mesh")
+        || mesh->getSettingBoolean("support_mesh")
+    )
+    {
+        return;
+    }
+
     setExtruder_addPrime(storage, gcode_layer, layer_nr, mesh->getSettingAsIndex("extruder_nr"));
 
     SliceLayer* layer = &mesh->layers[layer_nr];
@@ -622,7 +738,8 @@ void FffGcodeWriter::addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& stora
     }
 
     EZSeamType z_seam_type = mesh->getSettingAsZSeamType("z_seam_type");
-    gcode_layer.addPolygonsByOptimizer(polygons, &mesh->inset0_config, nullptr, z_seam_type, mesh->getSettingBoolean("magic_spiralize"));
+    Point z_seam_pos(mesh->getSettingInMicrons("z_seam_x"), mesh->getSettingInMicrons("z_seam_y"));
+    gcode_layer.addPolygonsByOptimizer(polygons, &mesh->inset0_config, nullptr, z_seam_type, z_seam_pos, mesh->getSettingInMicrons("wall_0_wipe_dist"), mesh->getSettingBoolean("magic_spiralize"));
 
     addMeshOpenPolyLinesToGCode(storage, mesh, gcode_layer, layer_nr);
 }
@@ -652,7 +769,14 @@ void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshSto
     {
         return;
     }
-    
+
+    if (mesh->getSettingBoolean("anti_overhang_mesh")
+        || mesh->getSettingBoolean("support_mesh")
+    )
+    {
+        return;
+    }
+
     SliceLayer* layer = &mesh->layers[layer_nr];
 
     if (layer->parts.size() == 0)
@@ -680,68 +804,23 @@ void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshSto
     setExtruder_addPrime(storage, gcode_layer, layer_nr, mesh->getSettingAsIndex("extruder_nr"));
 
     EZSeamType z_seam_type = mesh->getSettingAsZSeamType("z_seam_type");
-    PathOrderOptimizer part_order_optimizer(last_position_planned, z_seam_type);
+    Point z_seam_pos(mesh->getSettingInMicrons("z_seam_x"), mesh->getSettingInMicrons("z_seam_y"));
+    Point layer_start_position = last_position_planned;
+    if (storage.getSettingBoolean("start_layers_at_same_position"))
+    {
+        layer_start_position = Point(storage.getSettingInMicrons("layer_start_x"), storage.getSettingInMicrons("layer_start_y"));
+    }
+    PathOrderOptimizer part_order_optimizer(layer_start_position, z_seam_pos, z_seam_type);
     for(unsigned int partNr=0; partNr<layer->parts.size(); partNr++)
     {
         part_order_optimizer.addPolygon(layer->parts[partNr].insets[0][0]);
     }
     part_order_optimizer.optimize();
 
-    bool skin_alternate_rotation = mesh->getSettingBoolean("skin_alternate_rotation") && ( mesh->getSettingAsCount("top_layers") >= 4 || mesh->getSettingAsCount("bottom_layers") >= 4 );
-    
-    for(int order_idx : part_order_optimizer.polyOrder)
+    for (int part_idx : part_order_optimizer.polyOrder)
     {
-        SliceLayerPart& part = layer->parts[order_idx];
-
-        EFillMethod infill_pattern = mesh->getSettingAsFillMethod("infill_pattern");
-        int infill_angle = 45;
-        if ((infill_pattern == EFillMethod::LINES || infill_pattern == EFillMethod::ZIG_ZAG))
-        {
-            unsigned int combined_infill_layers = std::max(1U, round_divide(mesh->getSettingInMicrons("infill_sparse_thickness"), std::max(getSettingInMicrons("layer_height"), 1)));
-            if ((layer_nr / combined_infill_layers) & 1)
-            { // switch every [combined_infill_layers] layers
-                infill_angle += 90;
-            }
-        }
-        
-        int infill_line_distance = mesh->getSettingInMicrons("infill_line_distance");
-        int infill_overlap = mesh->getSettingInMicrons("infill_overlap_mm");
-        
-        gcode_layer.setIsInside(true); // going to print inside stuff below
-        
-        if (mesh->getSettingBoolean("infill_before_walls"))
-        {
-            processMultiLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
-            processSingleLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
-        }
-        
-        processInsets(gcode_layer, mesh, part, layer_nr, z_seam_type);
-
-        if (!mesh->getSettingBoolean("infill_before_walls"))
-        {
-            processMultiLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
-            processSingleLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
-        }
-
-        EFillMethod skin_pattern = mesh->getSettingAsFillMethod("top_bottom_pattern");
-        int skin_angle = 45;
-        if ((skin_pattern == EFillMethod::LINES || skin_pattern == EFillMethod::ZIG_ZAG) && layer_nr & 1)
-        {
-            skin_angle += 90; // should coincide with infill_angle (if both skin and infill are lines) so that the first top layer is orthogonal to the last infill layer
-        }
-        if (skin_alternate_rotation && ( layer_nr / 2 ) & 1)
-            skin_angle -= 45;
-
-        int64_t skin_overlap = mesh->getSettingInMicrons("skin_overlap_mm");
-        processSkin(gcode_layer, mesh, part, layer_nr, skin_overlap, skin_angle);
-
-        //After a layer part, make sure the nozzle is inside the comb boundary, so we do not retract on the perimeter.
-        if (!mesh->getSettingBoolean("magic_spiralize") || static_cast<int>(layer_nr) < mesh->getSettingAsCount("bottom_layers"))
-        {
-            gcode_layer.moveInsideCombBoundary(mesh->getSettingInMicrons((mesh->getSettingAsCount("wall_line_count") > 1) ? "wall_line_width_x" : "wall_line_width_0") * 1);
-        }
-
-        gcode_layer.setIsInside(false);
+        SliceLayerPart& part = layer->parts[part_idx];
+        addMeshPartToGCode(storage, mesh, part, gcode_layer, layer_nr);
     }
     if (mesh->getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL)
     {
@@ -749,6 +828,62 @@ void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshSto
     }
 }
 
+void FffGcodeWriter::addMeshPartToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, SliceLayerPart& part, GCodePlanner& gcode_layer, int layer_nr)
+{
+    bool skin_alternate_rotation = mesh->getSettingBoolean("skin_alternate_rotation") && ( mesh->getSettingAsCount("top_layers") >= 4 || mesh->getSettingAsCount("bottom_layers") >= 4 );
+
+    EFillMethod infill_pattern = mesh->getSettingAsFillMethod("infill_pattern");
+    int infill_angle = 0;
+    if ((infill_pattern == EFillMethod::LINES || infill_pattern == EFillMethod::ZIG_ZAG))
+    {
+        unsigned int combined_infill_layers = std::max(1U, round_divide(mesh->getSettingInMicrons("infill_sparse_thickness"), std::max(getSettingInMicrons("layer_height"), (coord_t)1)));
+        if ((layer_nr / combined_infill_layers) & 1)
+        { // switch every [combined_infill_layers] layers
+            infill_angle += 90;
+        }
+    }
+    
+    int infill_line_distance = mesh->getSettingInMicrons("infill_line_distance");
+    int infill_overlap = mesh->getSettingInMicrons("infill_overlap_mm");
+    
+    gcode_layer.setIsInside(true); // going to print inside stuff below
+    
+    if (mesh->getSettingBoolean("infill_before_walls"))
+    {
+        processMultiLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
+        processSingleLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
+    }
+
+    EZSeamType z_seam_type = mesh->getSettingAsZSeamType("z_seam_type");
+    Point z_seam_pos(mesh->getSettingInMicrons("z_seam_x"), mesh->getSettingInMicrons("z_seam_y"));
+    processInsets(gcode_layer, mesh, part, layer_nr, z_seam_type, z_seam_pos);
+
+    if (!mesh->getSettingBoolean("infill_before_walls"))
+    {
+        processMultiLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
+        processSingleLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
+    }
+
+    EFillMethod skin_pattern = mesh->getSettingAsFillMethod("top_bottom_pattern");
+    int skin_angle = 0;
+    if ((skin_pattern == EFillMethod::LINES || skin_pattern == EFillMethod::ZIG_ZAG) && layer_nr & 1)
+    {
+        skin_angle += 90; // should coincide with infill_angle (if both skin and infill are lines) so that the first top layer is orthogonal to the last infill layer
+    }
+    if (skin_alternate_rotation && ( layer_nr / 2 ) & 1)
+        skin_angle -= 45;
+
+    int64_t skin_overlap = mesh->getSettingInMicrons("skin_overlap_mm");
+    processSkinAndPerimeterGaps(gcode_layer, mesh, part, layer_nr, skin_overlap, skin_angle);
+
+    //After a layer part, make sure the nozzle is inside the comb boundary, so we do not retract on the perimeter.
+    if (!mesh->getSettingBoolean("magic_spiralize") || static_cast<int>(layer_nr) < mesh->getSettingAsCount("bottom_layers"))
+    {
+        gcode_layer.moveInsideCombBoundary(mesh->getSettingInMicrons((mesh->getSettingAsCount("wall_line_count") > 1) ? "wall_line_width_x" : "wall_line_width_0") * 1);
+    }
+
+    gcode_layer.setIsInside(false);
+}
 
             
 
@@ -775,8 +910,8 @@ void FffGcodeWriter::processMultiLayerInfill(GCodePlanner& gcode_layer, SliceMes
                     infill_line_distance_here /= 2;
                 }
                 
-                Infill infill_comp(infill_pattern, part.infill_area_per_combine_per_density[density_idx][combine_idx], 0, infill_line_width, infill_line_distance_here, infill_overlap, infill_angle, z, infill_shift, false, false);
-                infill_comp.generate(infill_polygons, infill_lines);
+                Infill infill_comp(infill_pattern, part.infill_area_per_combine_per_density[density_idx][combine_idx], 0, infill_line_width, infill_line_distance_here, infill_overlap, infill_angle, z, infill_shift);
+                infill_comp.generate(infill_polygons, infill_lines, mesh);
             }
             gcode_layer.addPolygonsByOptimizer(infill_polygons, &mesh->infill_config[combine_idx]);
             gcode_layer.addLinesByOptimizer(infill_lines, &mesh->infill_config[combine_idx], (infill_pattern == EFillMethod::ZIG_ZAG)? SpaceFillType::PolyLines : SpaceFillType::Lines);
@@ -831,8 +966,8 @@ void FffGcodeWriter::processSingleLayerInfill(GCodePlanner& gcode_layer, SliceMe
 //     ^   highest density line dist
             infill_line_distance_here /= 2;
         }
-        Infill infill_comp(pattern, part.infill_area_per_combine_per_density[density_idx][0], 0, infill_line_width, infill_line_distance_here, infill_overlap, infill_angle, z, infill_shift, false, false);
-        infill_comp.generate(infill_polygons, infill_lines);
+        Infill infill_comp(pattern, part.infill_area_per_combine_per_density[density_idx][0], 0, infill_line_width, infill_line_distance_here, infill_overlap, infill_angle, z, infill_shift);
+        infill_comp.generate(infill_polygons, infill_lines, mesh);
     }
     gcode_layer.addPolygonsByOptimizer(infill_polygons, &mesh->infill_config[0]);
     if (pattern == EFillMethod::GRID || pattern == EFillMethod::LINES || pattern == EFillMethod::TRIANGLES)
@@ -845,7 +980,7 @@ void FffGcodeWriter::processSingleLayerInfill(GCodePlanner& gcode_layer, SliceMe
     }
 }
 
-void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, EZSeamType z_seam_type)
+void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, EZSeamType z_seam_type, Point z_seam_pos)
 {
     bool compensate_overlap_0 = mesh->getSettingBoolean("travel_compensate_overlapping_walls_0_enabled");
     bool compensate_overlap_x = mesh->getSettingBoolean("travel_compensate_overlapping_walls_x_enabled");
@@ -860,7 +995,9 @@ void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage*
             }
             if (static_cast<int>(layer_nr) == mesh->getSettingAsCount("bottom_layers") && part.insets.size() > 0)
             { // on the last normal layer first make the outer wall normally and then start a second outer wall from the same hight, but gradually moving upward
-                gcode_layer.addPolygonsByOptimizer(part.insets[0], &mesh->insetX_config, nullptr, EZSeamType::SHORTEST, false);
+                WallOverlapComputation* wall_overlap_computation(nullptr);
+                int wall_0_wipe_dist(0);
+                gcode_layer.addPolygonsByOptimizer(part.insets[0], &mesh->insetX_config, wall_overlap_computation, EZSeamType::SHORTEST, z_seam_pos, mesh->getSettingInMicrons("wall_0_wipe_dist"), wall_0_wipe_dist);
             }
         }
         int processed_inset_number = -1;
@@ -875,13 +1012,14 @@ void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage*
             {
                 if (!compensate_overlap_0)
                 {
-                    gcode_layer.addPolygonsByOptimizer(part.insets[0], &mesh->inset0_config, nullptr, z_seam_type, spiralize);
+                    WallOverlapComputation* wall_overlap_computation(nullptr);
+                    gcode_layer.addPolygonsByOptimizer(part.insets[0], &mesh->inset0_config, wall_overlap_computation, z_seam_type, z_seam_pos, mesh->getSettingInMicrons("wall_0_wipe_dist"), spiralize);
                 }
                 else
                 {
                     Polygons& outer_wall = part.insets[0];
                     WallOverlapComputation wall_overlap_computation(outer_wall, mesh->getSettingInMicrons("wall_line_width_0"));
-                    gcode_layer.addPolygonsByOptimizer(outer_wall, &mesh->inset0_config, &wall_overlap_computation, z_seam_type, spiralize);
+                    gcode_layer.addPolygonsByOptimizer(outer_wall, &mesh->inset0_config, &wall_overlap_computation, z_seam_type, z_seam_pos, mesh->getSettingInMicrons("wall_0_wipe_dist"), spiralize);
                 }
             }
             else
@@ -902,13 +1040,27 @@ void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage*
 }
 
 
-void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, int skin_overlap, int skin_angle)
+void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, int skin_overlap, int skin_angle)
 {
     int64_t z = layer_nr * getSettingInMicrons("layer_height");
     const unsigned int skin_line_width = mesh->skin_config.getLineWidth();
 
-    for(SkinPart& skin_part : part.skin_parts) // TODO: optimize parts order
+    constexpr int perimeter_gaps_extra_offset = 15; // extra offset so that the perimeter gaps aren't created everywhere due to rounding errors
+    bool fill_perimeter_gaps = mesh->getSettingAsFillPerimeterGapMode("fill_perimeter_gaps") != FillPerimeterGapMode::NOWHERE;
+
+    Point z_seam_pos(0, 0); // not used
+    PathOrderOptimizer part_order_optimizer(gcode_layer.getLastPosition(), z_seam_pos, EZSeamType::SHORTEST);
+    for (unsigned int skin_part_idx = 0; skin_part_idx < part.skin_parts.size(); skin_part_idx++)
     {
+        PolygonsPart& outline = part.skin_parts[skin_part_idx].outline;
+        part_order_optimizer.addPolygon(outline.outerPolygon());
+    }
+    part_order_optimizer.optimize();
+
+    for (int ordered_skin_part_idx : part_order_optimizer.polyOrder)
+    {
+        SkinPart& skin_part = part.skin_parts[ordered_skin_part_idx];
+
         Polygons skin_polygons;
         Polygons skin_lines;
         
@@ -921,6 +1073,9 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
             pattern = EFillMethod::LINES;
             skin_angle = bridge;
         }
+
+        Polygons perimeter_gaps; // the perimeter gaps of the insets of this skin part
+
         Polygons* inner_skin_outline = nullptr;
         int offset_from_inner_skin_outline = 0;
         if (pattern != EFillMethod::CONCENTRIC)
@@ -933,6 +1088,21 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
             {
                 inner_skin_outline = &skin_part.insets.back();
                 offset_from_inner_skin_outline = -mesh->insetX_config.getLineWidth() / 2;
+
+                if (fill_perimeter_gaps)
+                {
+                    // add perimeter gaps between the outer skin inset and the innermost wall
+                    const Polygons outer = skin_part.outline;
+                    const Polygons inner = skin_part.insets[0].offset(mesh->insetX_config.getLineWidth() / 2 + perimeter_gaps_extra_offset);
+                    perimeter_gaps.add(outer.difference(inner));
+
+                    for (unsigned int inset_idx = 1; inset_idx < skin_part.insets.size(); inset_idx++)
+                    { // add perimeter gaps between consecutive skin walls
+                        const Polygons outer = skin_part.insets[inset_idx - 1].offset(-1 * mesh->insetX_config.getLineWidth() / 2 - perimeter_gaps_extra_offset);
+                        const Polygons inner = skin_part.insets[inset_idx].offset(mesh->insetX_config.getLineWidth() / 2);
+                        perimeter_gaps.add(outer.difference(inner));
+                    }
+                }
             }
         }
 
@@ -942,9 +1112,17 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
         }
 
         int extra_infill_shift = 0;
-        Infill infill_comp(pattern, *inner_skin_outline, offset_from_inner_skin_outline, skin_line_width, skin_line_width, skin_overlap, skin_angle, z, extra_infill_shift, false, false);
+        Polygons* perimeter_gaps_output = (fill_perimeter_gaps)? &perimeter_gaps : nullptr;
+        Infill infill_comp(pattern, *inner_skin_outline, offset_from_inner_skin_outline, skin_line_width, skin_line_width, skin_overlap, skin_angle, z, extra_infill_shift, perimeter_gaps_output);
         infill_comp.generate(skin_polygons, skin_lines);
 
+        if (fill_perimeter_gaps)
+        { // handle perimeter_gaps of skin insets
+            int offset = 0;
+            Infill infill_comp(EFillMethod::LINES, perimeter_gaps, offset, skin_line_width, skin_line_width, skin_overlap, skin_angle, z, extra_infill_shift);
+            infill_comp.generate(skin_polygons, skin_lines);
+        }
+
         gcode_layer.addPolygonsByOptimizer(skin_polygons, &mesh->skin_config);
 
         if (pattern == EFillMethod::GRID || pattern == EFillMethod::LINES || pattern == EFillMethod::TRIANGLES)
@@ -956,57 +1134,81 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
             gcode_layer.addLinesByOptimizer(skin_lines, &mesh->skin_config, (pattern == EFillMethod::ZIG_ZAG)? SpaceFillType::PolyLines : SpaceFillType::Lines);
         }
     }
+
+    if (fill_perimeter_gaps)
+    { // handle perimeter gaps of normal insets
+        Polygons perimeter_gaps;
+        int line_width = mesh->inset0_config.getLineWidth();
+        for (unsigned int inset_idx = 0; inset_idx < part.insets.size() - 1; inset_idx++)
+        {
+            const Polygons outer = part.insets[inset_idx].offset(-1 * line_width / 2 - perimeter_gaps_extra_offset);
+            line_width = mesh->insetX_config.getLineWidth();
+
+            Polygons inner = part.insets[inset_idx + 1].offset(line_width / 2);
+            perimeter_gaps.add(outer.difference(inner));
+        }
+        { // gap between inner wall and skin/infill
+            if (mesh->getSettingInMicrons("infill_line_distance") > 0 && !mesh->getSettingBoolean("infill_hollow"))
+            {
+                const Polygons outer = part.insets.back().offset(-1 * line_width / 2 - perimeter_gaps_extra_offset);
+
+                Polygons inner = part.infill_area;
+                for (SkinPart& skin_part : part.skin_parts)
+                {
+                    inner.add(skin_part.outline);
+                }
+                perimeter_gaps.add(outer.difference(inner));
+            }
+        }
+
+        Polygons skin_polygons; // unused
+        Polygons skin_lines; // soon to be generated gap filler lines
+        int offset = 0;
+        int extra_infill_shift = 0;
+        Infill infill_comp(EFillMethod::LINES, perimeter_gaps, offset, skin_line_width, skin_line_width, skin_overlap, skin_angle, z, extra_infill_shift);
+        infill_comp.generate(skin_polygons, skin_lines);
+
+        gcode_layer.addLinesByOptimizer(skin_lines, &mesh->skin_config, SpaceFillType::Lines);
+    }
 }
 
-void FffGcodeWriter::addSupportToGCode(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr, int extruder_nr_before, bool before_rest)
+bool FffGcodeWriter::addSupportToGCode(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr, int extruder_nr)
 {
+    bool support_added = false;
     if (!storage.support.generated || layer_nr > storage.support.layer_nr_max_filled_layer)
-        return; 
-    
-    int support_skin_extruder_nr = getSettingAsIndex("support_interface_extruder_nr");
-    int support_infill_extruder_nr = (layer_nr == 0)? getSettingAsIndex("support_extruder_nr_layer_0") : getSettingAsIndex("support_infill_extruder_nr");
-    
-    bool print_support_before_rest = support_infill_extruder_nr == extruder_nr_before
-                                    || support_skin_extruder_nr == extruder_nr_before;
-    // TODO: always print support after rest when only one nozzle is used for the whole meshgroup
-    
-    if (print_support_before_rest != before_rest)
-        return;
-    
+    {
+        return support_added;
+    }
+
+    int support_interface_extruder_nr = getSettingAsIndex("support_interface_extruder_nr");
+    int support_infill_extruder_nr = (layer_nr <= 0)? getSettingAsIndex("support_extruder_nr_layer_0") : getSettingAsIndex("support_infill_extruder_nr");
+
     SupportLayer& support_layer = storage.support.supportLayers[layer_nr];
     if (support_layer.skin.size() == 0 && support_layer.supportAreas.size() == 0)
     {
-        return;
+        return support_added;
     }
-    
-    int current_extruder_nr = gcode_layer.getExtruder();
-    
-    if (support_layer.skin.size() > 0)
+
+
+    if (extruder_nr == support_infill_extruder_nr)
     {
-        if (support_skin_extruder_nr != support_infill_extruder_nr && support_skin_extruder_nr == current_extruder_nr)
-        {
-            addSupportRoofsToGCode(storage, gcode_layer, layer_nr);
-            addSupportInfillToGCode(storage, gcode_layer, layer_nr);
-        }
-        else 
-        {
-            addSupportInfillToGCode(storage, gcode_layer, layer_nr);
-            addSupportRoofsToGCode(storage, gcode_layer, layer_nr);
-        }
+        support_added |= addSupportInfillToGCode(storage, gcode_layer, layer_nr);
     }
-    else
+    if (extruder_nr == support_interface_extruder_nr)
     {
-        addSupportInfillToGCode(storage, gcode_layer, layer_nr);
+        support_added |= addSupportRoofsToGCode(storage, gcode_layer, layer_nr);
     }
+    return support_added;
 }
 
-void FffGcodeWriter::addSupportInfillToGCode(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr)
+bool FffGcodeWriter::addSupportInfillToGCode(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr)
 {
+    bool added = false;
     if (!storage.support.generated 
         || layer_nr > storage.support.layer_nr_max_filled_layer 
         || storage.support.supportLayers[layer_nr].supportAreas.size() == 0)
     {
-        return;
+        return added;
     }
 
     int64_t z = layer_nr * getSettingInMicrons("layer_height");
@@ -1015,12 +1217,12 @@ void FffGcodeWriter::addSupportInfillToGCode(SliceDataStorage& storage, GCodePla
     int support_line_distance = infill_extr.getSettingInMicrons("support_line_distance"); // first layer line distance must be the same as the second layer line distance
     const int support_line_width = storage.support_config.getLineWidth();
     EFillMethod support_pattern = infill_extr.getSettingAsFillMethod("support_pattern"); // first layer pattern must be same as other layers
-    if (layer_nr == 0 && (support_pattern == EFillMethod::LINES || support_pattern == EFillMethod::ZIG_ZAG)) { support_pattern = EFillMethod::GRID; }
+    if (layer_nr <= 0 && (support_pattern == EFillMethod::LINES || support_pattern == EFillMethod::ZIG_ZAG)) { support_pattern = EFillMethod::GRID; }
 
-    int infill_extruder_nr_here = (layer_nr == 0)? getSettingAsIndex("support_extruder_nr_layer_0") : getSettingAsIndex("support_infill_extruder_nr");
+    int infill_extruder_nr_here = (layer_nr <= 0)? getSettingAsIndex("support_extruder_nr_layer_0") : getSettingAsIndex("support_infill_extruder_nr");
     const ExtruderTrain& infill_extr_here = *storage.meshgroup->getExtruderTrain(infill_extruder_nr_here);
 
-    Polygons& support = storage.support.supportLayers[layer_nr].supportAreas;
+    Polygons& support = storage.support.supportLayers[std::max(0, layer_nr)].supportAreas;
 
     std::vector<PolygonsPart> support_islands = support.splitIntoParts();
 
@@ -1051,7 +1253,10 @@ void FffGcodeWriter::addSupportInfillToGCode(SliceDataStorage& storage, GCodePla
         }
 
         int extra_infill_shift = 0;
-        Infill infill_comp(support_pattern, island, offset_from_outline, support_line_width, support_line_distance, support_infill_overlap, 0, z, extra_infill_shift, infill_extr.getSettingBoolean("support_connect_zigzags"), true);
+        bool use_endpieces = true;
+        Polygons* perimeter_gaps = nullptr;
+        double fill_angle = 0;
+        Infill infill_comp(support_pattern, island, offset_from_outline, support_line_width, support_line_distance, support_infill_overlap, fill_angle, z, extra_infill_shift, perimeter_gaps, infill_extr.getSettingBoolean("support_connect_zigzags"), use_endpieces);
         Polygons support_polygons;
         Polygons support_lines;
         infill_comp.generate(support_polygons, support_lines);
@@ -1060,24 +1265,26 @@ void FffGcodeWriter::addSupportInfillToGCode(SliceDataStorage& storage, GCodePla
             setExtruder_addPrime(storage, gcode_layer, layer_nr, infill_extruder_nr_here); // only switch extruder if we're sure we're going to switch
             gcode_layer.addPolygonsByOptimizer(support_polygons, &storage.support_config);
             gcode_layer.addLinesByOptimizer(support_lines, &storage.support_config, (support_pattern == EFillMethod::ZIG_ZAG)? SpaceFillType::PolyLines : SpaceFillType::Lines);
+            added = true;
         }
     }
+    return added;
 }
 
-void FffGcodeWriter::addSupportRoofsToGCode(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr)
+bool FffGcodeWriter::addSupportRoofsToGCode(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr)
 {
+    bool added = false;
     if (!storage.support.generated 
         || layer_nr > storage.support.layer_nr_max_filled_layer 
-        || storage.support.supportLayers[layer_nr].skin.size() == 0)
+        || storage.support.supportLayers[std::max(0, layer_nr)].skin.size() == 0)
     {
-        return;
+        return added;
     }
 
     int64_t z = layer_nr * getSettingInMicrons("layer_height");
 
     int skin_extruder_nr = getSettingAsIndex("support_interface_extruder_nr");
     const ExtruderTrain& interface_extr = *storage.meshgroup->getExtruderTrain(skin_extruder_nr);
-    setExtruder_addPrime(storage, gcode_layer, layer_nr, skin_extruder_nr);
 
     EFillMethod pattern = interface_extr.getSettingAsFillMethod("support_interface_pattern");
     int support_line_distance = interface_extr.getSettingInMicrons("support_interface_line_distance");
@@ -1104,19 +1311,28 @@ void FffGcodeWriter::addSupportRoofsToGCode(SliceDataStorage& storage, GCodePlan
     }
     else 
     {
-        fillAngle = 45 + (layer_nr % 2) * 90; // alternate between the two kinds of diagonal:  / and \ .
+        fillAngle = 0 + (((layer_nr % 2) + 2) % 2) * 90; // alternate between the two kinds of diagonal:  / and \ .
+        // +2) %2 to handle negative layer numbers
     }
     int support_skin_overlap = 0; // the skin (roofs/bottoms) should never be expanded outwards
     int outline_offset =  0;
     int extra_infill_shift = 0;
-    
-    Infill infill_comp(pattern, storage.support.supportLayers[layer_nr].skin, outline_offset, storage.support_skin_config.getLineWidth(), support_line_distance, support_skin_overlap, fillAngle, z, extra_infill_shift, false, true);
+    Polygons* perimeter_gaps = nullptr;
+    bool use_endpieces = true;
+    bool connected_zigzags = false;
+    Infill infill_comp(pattern, storage.support.supportLayers[std::max(0, layer_nr)].skin, outline_offset, storage.support_skin_config.getLineWidth(), support_line_distance, support_skin_overlap, fillAngle, z, extra_infill_shift, perimeter_gaps, connected_zigzags, use_endpieces);
     Polygons support_polygons;
     Polygons support_lines;
     infill_comp.generate(support_polygons, support_lines);
 
-    gcode_layer.addPolygonsByOptimizer(support_polygons, &storage.support_skin_config);
-    gcode_layer.addLinesByOptimizer(support_lines, &storage.support_skin_config, (pattern == EFillMethod::ZIG_ZAG)? SpaceFillType::PolyLines : SpaceFillType::Lines);
+    if (support_lines.size() > 0 || support_polygons.size() > 0)
+    {
+        setExtruder_addPrime(storage, gcode_layer, layer_nr, skin_extruder_nr);
+        gcode_layer.addPolygonsByOptimizer(support_polygons, &storage.support_skin_config);
+        gcode_layer.addLinesByOptimizer(support_lines, &storage.support_skin_config, (pattern == EFillMethod::ZIG_ZAG)? SpaceFillType::PolyLines : SpaceFillType::Lines);
+        added = true;
+    }
+    return added;
 }
 
 void FffGcodeWriter::setExtruder_addPrime(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr, int extruder_nr)
@@ -1130,29 +1346,40 @@ void FffGcodeWriter::setExtruder_addPrime(SliceDataStorage& storage, GCodePlanne
     
     if (extruder_changed)
     {
+        if (!extruder_prime_is_planned[extruder_nr])
+        {
+            ExtruderTrain* train = storage.meshgroup->getExtruderTrain(extruder_nr);
+
+            // move to prime position
+            bool prime_pos_is_abs = train->getSettingBoolean("extruder_prime_pos_abs");
+            Point prime_pos = Point(train->getSettingInMicrons("extruder_prime_pos_x"), train->getSettingInMicrons("extruder_prime_pos_y"));
+            gcode_layer.addTravel(prime_pos_is_abs? prime_pos : gcode_layer.getLastPosition() + prime_pos);
+
+            gcode_layer.planPrime();
+
+            extruder_prime_is_planned[extruder_nr] = true;
+        }
+
+        assert(extruder_prime_is_planned[extruder_nr] && "extruders should be primed before they are used!");
         if (layer_nr == 0 && !skirt_brim_is_processed[extruder_nr])
         {
             processSkirtBrim(storage, gcode_layer, extruder_nr);
         }
-        else
+        if (layer_nr >= -Raft::getFillerLayerCount(storage))
         {
             addPrimeTower(storage, gcode_layer, layer_nr, previous_extruder);
-            
         }
     }
 }
 
-void FffGcodeWriter::addPrimeTower(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr, int prev_extruder)
+void FffGcodeWriter::addPrimeTower(SliceDataStorage& storage, GCodePlanner& gcode_layer, int layer_nr, int prev_extruder)
 {
-    
     if (!getSettingBoolean("prime_tower_enable"))
     {
         return;
     }
 
-    bool wipe = getSettingBoolean("prime_tower_wipe_enabled");
-
-    storage.primeTower.addToGcode(storage, gcodeLayer, gcode, layer_nr, prev_extruder, wipe);
+    storage.primeTower.addToGcode(storage, gcode_layer, gcode, layer_nr, prev_extruder, gcode_layer.getExtruder());
 }
 
 void FffGcodeWriter::finalize()

src/FffGcodeWriter.h

@@ -65,6 +65,13 @@ private:
      */
     bool skirt_brim_is_processed[MAX_EXTRUDERS];
 
+    std::vector<std::vector<unsigned int>> mesh_order_per_extruder; //!< For each extruder, the cyclic order of the meshes (the first element is not the starting element per se)
+
+    /*!
+     * For each extruder whether priming has already been planned
+     */
+    bool extruder_prime_is_planned[MAX_EXTRUDERS];
+
     std::vector<FanSpeedLayerTimeSettings> fan_speed_layer_time_settings_per_extruder; //!< The settings used relating to minimal layer time and fan speeds. Configured for each extruder.
 
     Point last_position_planned; //!< The position of the head before planning the next layer
@@ -73,12 +80,13 @@ private:
 public:
     FffGcodeWriter(SettingsBase* settings_)
     : SettingsMessenger(settings_)
+    , max_object_height(0)
     , layer_plan_buffer(this, gcode)
+    , extruder_prime_is_planned {} // initialize all values in array with [false]
     , last_position_planned(no_point)
     , current_extruder_planned(0) // changed somewhere early in FffGcodeWriter::writeGCode
     , is_inside_mesh_layer_part(false)
     {
-        max_object_height = 0;
     }
 
     /*!
@@ -175,15 +183,26 @@ private:
      * \param[out] storage The data storage to which to save the configurations.
      */
     void initConfigs(SliceDataStorage& storage);
-    
+
+    /*!
+     * Get the extruder with which to start the print.
+     * 
+     * Generally this is the adhesion_extruder_nr, but in case the platform adhesion type is none,
+     * the extruder with lowest number which is used on the first layer is used as initial extruder.
+     * 
+     * \param[in] storage where to get settings from.
+     */
+    unsigned int getStartExtruder(SliceDataStorage& storage);
+
     /*!
      * Set temperatures and perform initial priming.
      * 
      * Write a stub header if CuraEngine is in command line tool mode. (Cause writing the header afterwards would entail moving all gcode down.)
      * 
      * \param[in] storage where the slice data is stored.
+     * \param[in] start_extruder_nr The extruder with which to start the print.
      */
-    void processStartingCode(SliceDataStorage& storage);
+    void processStartingCode(SliceDataStorage& storage, const unsigned int start_extruder_nr);
 
     /*!
      * Move up and over the already printed meshgroups to print the next meshgroup.
@@ -211,7 +230,22 @@ private:
      * \param total_layers The total number of layers.
      */
     void processLayer(SliceDataStorage& storage, int layer_nr, unsigned int total_layers);
-    
+
+    /*!
+     * Whether the extruders need to be primed separately just before they are used.
+     * 
+     * \return whether the extruders need to be primed separately just before they are used
+     */
+    bool getExtrudersNeedPrimeDuringFirstLayer();
+
+    /*!
+     * Plan priming of all used extruders which haven't been primed yet
+     * \param[in] storage where the slice data is stored.
+     * \param layer_plan The initial planning of the g-code of the layer.
+     * \param layer_nr The index of the layer to write the gcode of.
+     */
+    void ensureAllExtrudersArePrimed(SliceDataStorage& storage, GCodePlanner& layer_plan, const int layer_nr);
+
     /*!
      * Add the skirt or the brim to the layer plan \p gcodeLayer.
      * 
@@ -239,16 +273,25 @@ private:
      * \param layer_nr The index of the layer to write the gcode of.
      */
     void processDraftShield(SliceDataStorage& storage, GCodePlanner& gcodeLayer, unsigned int layer_nr);
-    
+
     /*!
-     * Calculate in which order to print the meshes.
+     * Calculate in which order to plan the extruders
      * 
      * \param[in] storage where the slice data is stored.
      * \param current_extruder The current extruder with which we last printed
-     * \return A vector of mesh indices ordered on print order.
+     * \return A vector of pairs of extruder numbers coupled with the mesh indices ordered on print order for that extruder.
      */
-    std::vector<unsigned int> calculateMeshOrder(SliceDataStorage& storage, int current_extruder);
-        
+    std::vector<int> calculateExtruderOrder(SliceDataStorage& storage, int current_extruder);
+
+    /*!
+     * Calculate in which order to plan the meshes of a specific extruder
+     * 
+     * \param[in] storage where the slice data is stored.
+     * \param extruder_nr The extruder for which to determine the order
+     * \return A vector of pairs of extruder numbers coupled with the mesh indices ordered on print order for that extruder.
+     */
+    std::vector<unsigned int> calculateMeshOrder(SliceDataStorage& storage, int extruder_nr);
+
     /*!
      * Add a single layer from a single mesh-volume to the layer plan \p gcodeLayer in mesh surface mode.
      * 
@@ -272,15 +315,27 @@ private:
     void addMeshOpenPolyLinesToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr);
     
     /*!
-     * Add a single layer from a single mesh-volume to the layer plan \p gcodeLayer.
+     * Add a single layer from a single mesh-volume to the layer plan \p gcode_layer.
      * 
      * \param[in] storage where the slice data is stored.
-     * \param mesh The mesh to add to the layer plan \p gcodeLayer.
-     * \param gcodeLayer The initial planning of the gcode of the layer.
+     * \param mesh The mesh to add to the layer plan \p gcode_layer.
+     * \param gcode_layer The initial planning of the gcode of the layer.
      * \param layer_nr The index of the layer to write the gcode of.
      * 
      */
-    void addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcodeLayer, int layer_nr);
+    void addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr);
+
+    /*!
+     * Add a single part from a given layer of a mesh-volume to the layer plan \p gcode_layer.
+     * 
+     * \param[in] storage where the slice data is stored.
+     * \param mesh The mesh to add to the layer plan \p gcode_layer.
+     * \param part The part to add
+     * \param gcode_layer The initial planning of the gcode of the layer.
+     * \param layer_nr The index of the layer to write the gcode of.
+     * 
+     */
+    void addMeshPartToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, SliceLayerPart& part, GCodePlanner& gcode_layer, int layer_nr);
     
     /*!
      * Add thicker (multiple layers) sparse infill for a given part in a layer plan.
@@ -314,44 +369,50 @@ private:
      * \param part The part for which to create gcode
      * \param layer_nr The current layer number.
      * \param z_seam_type dir3ective for where to start the outer paerimeter of a part
+     * \param z_seam_pos The location near where to start the outer inset in case \p z_seam_type is 'back'
      */
-    void processInsets(GCodePlanner& gcodeLayer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, EZSeamType z_seam_type);
+    void processInsets(GCodePlanner& gcodeLayer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, EZSeamType z_seam_type, Point z_seam_pos);
     
     
     /*!
-     * Add the gcode of the top/bottom skin of the given part.
+     * Add the gcode of the top/bottom skin of the given part and of the perimeter gaps.
+     * 
+     * Perimter gaps are generated for skin outlines and printed while the skin fill of the skin part is printed.
+     * Perimeter gaps between the walls are added to the gcode afterwards.
+     * 
      * \param gcodeLayer The initial planning of the gcode of the layer.
      * \param mesh The mesh for which to add to the layer plan \p gcodeLayer.
      * \param part The part for which to create gcode
      * \param layer_nr The current layer number.
-     * \param skin_overlap The distance by which the skin overlaps with the wall insets.
+     * \param skin_overlap The distance by which the skin overlaps with the wall insets and the distance by which the perimeter gaps overlap with adjacent print features.
      * \param fillAngle The angle in the XY plane at which the infill is generated.
      */
-    void processSkin(cura::GCodePlanner& gcode_layer, cura::SliceMeshStorage* mesh, cura::SliceLayerPart& part, unsigned int layer_nr, int skin_overlap, int infill_angle);
-    
+    void processSkinAndPerimeterGaps(cura::GCodePlanner& gcode_layer, cura::SliceMeshStorage* mesh, cura::SliceLayerPart& part, unsigned int layer_nr, int skin_overlap, int infill_angle);
+
     /*!
-     * Add the support to the layer plan \p gcodeLayer of the current layer.
+     * Add the support to the layer plan \p gcodeLayer of the current layer for all support parts with the given \p extruder_nr.
      * \param[in] storage where the slice data is stored.
      * \param gcodeLayer The initial planning of the gcode of the layer.
      * \param layer_nr The index of the layer to write the gcode of.
-     * \param extruder_nr_before The extruder number at the start of the layer (before other print parts aka the rest)
-     * \param before_rest Whether the function has been called before adding the rest to the layer plan \p gcodeLayer, or after.
+     * \return whether any support was added to the layer plan
      */
-    void addSupportToGCode(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr, int extruder_nr_before, bool before_rest);
+    bool addSupportToGCode(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr, int extruder_nr);
     /*!
      * Add the support lines/walls to the layer plan \p gcodeLayer of the current layer.
      * \param[in] storage where the slice data is stored.
      * \param gcodeLayer The initial planning of the gcode of the layer.
      * \param layer_nr The index of the layer to write the gcode of.
+     * \return whether any support infill was added to the layer plan
      */
-    void addSupportInfillToGCode(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr);
+    bool addSupportInfillToGCode(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr);
     /*!
      * Add the support skins to the layer plan \p gcodeLayer of the current layer.
      * \param[in] storage where the slice data is stored.
      * \param gcodeLayer The initial planning of the gcode of the layer.
      * \param layer_nr The index of the layer to write the gcode of.
+     * \return whether any support skin was added to the layer plan
      */
-    void addSupportRoofsToGCode(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr);
+    bool addSupportRoofsToGCode(SliceDataStorage& storage, GCodePlanner& gcodeLayer, int layer_nr);
     
     /*!
      * Change to a new extruder, and add the prime tower instructions if the new extruder is different from the last.

src/FffPolygonGenerator.cpp

@@ -4,6 +4,7 @@
 #include <map> // multimap (ordered map allowing duplicate keys)
 
 #include "utils/math.h"
+#include "utils/algorithm.h"
 #include "slicer.h"
 #include "utils/gettime.h"
 #include "utils/logoutput.h"
@@ -52,7 +53,7 @@ unsigned int FffPolygonGenerator::getDraftShieldLayerCount(const unsigned int to
         case DraftShieldHeightLimitation::FULL:
             return total_layers;
         case DraftShieldHeightLimitation::LIMITED:
-            return std::max(0, (getSettingInMicrons("draft_shield_height") - getSettingInMicrons("layer_height_0")) / getSettingInMicrons("layer_height") + 1);
+            return std::max((coord_t)0, (getSettingInMicrons("draft_shield_height") - getSettingInMicrons("layer_height_0")) / getSettingInMicrons("layer_height") + 1);
     }
 }
 
@@ -107,7 +108,7 @@ bool FffPolygonGenerator::sliceModel(MeshGroup* meshgroup, TimeKeeper& timeKeepe
     for(unsigned int meshIdx=0; meshIdx < slicerList.size(); meshIdx++)
     {
         Mesh& mesh = storage.meshgroup->meshes[meshIdx];
-        if (mesh.getSettingBoolean("conical_overhang_enabled"))
+        if (mesh.getSettingBoolean("conical_overhang_enabled") && !mesh.getSettingBoolean("anti_overhang_mesh"))
         {
             ConicalOverhang::apply(slicerList[meshIdx], mesh.getSettingInAngleRadians("conical_overhang_angle"), layer_thickness);
         }
@@ -115,16 +116,54 @@ bool FffPolygonGenerator::sliceModel(MeshGroup* meshgroup, TimeKeeper& timeKeepe
 
     Progress::messageProgressStage(Progress::Stage::PARTS, &timeKeeper);
 
-    carveMultipleVolumes(slicerList);
+    if (storage.getSettingBoolean("carve_multiple_volumes"))
+    {
+        carveMultipleVolumes(slicerList, storage.getSettingBoolean("alternate_carve_order"));
+    }
     generateMultipleVolumesOverlap(slicerList);
 
+    storage.print_layer_count = 0;
+    for (unsigned int meshIdx = 0; meshIdx < slicerList.size(); meshIdx++)
+    {
+        Mesh& mesh = storage.meshgroup->meshes[meshIdx];
+        Slicer* slicer = slicerList[meshIdx];
+        if (!mesh.getSettingBoolean("anti_overhang_mesh") && !mesh.getSettingBoolean("infill_mesh"))
+        {
+            storage.print_layer_count = std::max(storage.print_layer_count, (unsigned int)slicer->layers.size());
+        }
+    }
+    storage.support.supportLayers.resize(storage.print_layer_count);
+
     storage.meshes.reserve(slicerList.size()); // causes there to be no resize in meshes so that the pointers in sliceMeshStorage._config to retraction_config don't get invalidated.
     for (unsigned int meshIdx = 0; meshIdx < slicerList.size(); meshIdx++)
     {
         Slicer* slicer = slicerList[meshIdx];
+        Mesh& mesh = storage.meshgroup->meshes[meshIdx];
+
+        // always make a new SliceMeshStorage, so that they have the same ordering / indexing as meshgroup.meshes
         storage.meshes.emplace_back(&meshgroup->meshes[meshIdx], slicer->layers.size()); // new mesh in storage had settings from the Mesh
         SliceMeshStorage& meshStorage = storage.meshes.back();
-        Mesh& mesh = storage.meshgroup->meshes[meshIdx];
+
+        if (mesh.getSettingBoolean("anti_overhang_mesh"))
+        {
+            for (unsigned int layer_nr = 0; layer_nr < slicer->layers.size(); layer_nr++)
+            {
+                SupportLayer& support_layer = storage.support.supportLayers[layer_nr];
+                SlicerLayer& slicer_layer = slicer->layers[layer_nr];
+                support_layer.anti_overhang = support_layer.anti_overhang.unionPolygons(slicer_layer.polygons);
+            }
+            continue;
+        }
+        if (mesh.getSettingBoolean("support_mesh"))
+        {
+            for (unsigned int layer_nr = 0; layer_nr < slicer->layers.size(); layer_nr++)
+            {
+                SupportLayer& support_layer = storage.support.supportLayers[layer_nr];
+                SlicerLayer& slicer_layer = slicer->layers[layer_nr];
+                support_layer.support_mesh.add(slicer_layer.polygons);
+            }
+            continue;
+        }
 
         createLayerParts(meshStorage, slicer, mesh.getSettingBoolean("meshfix_union_all"), mesh.getSettingBoolean("meshfix_union_all_remove_holes"));
         delete slicerList[meshIdx];
@@ -168,7 +207,7 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
     unsigned int slice_layer_count = 0;
     for (SliceMeshStorage& mesh : storage.meshes)
     {
-        if (!mesh.getSettingBoolean("infill_mesh"))
+        if (!mesh.getSettingBoolean("infill_mesh") && !mesh.getSettingBoolean("anti_overhang_mesh"))
         {
             slice_layer_count = std::max<unsigned int>(slice_layer_count, mesh.layers.size());
         }
@@ -197,11 +236,10 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
     }
     for (unsigned int mesh_order_idx(0); mesh_order_idx < mesh_order.size(); ++mesh_order_idx)
     {
-        processBasicWallsSkinInfill(storage, mesh_order_idx, mesh_order, slice_layer_count, inset_skin_progress_estimate);
+        processBasicWallsSkinInfill(storage, mesh_order_idx, mesh_order, inset_skin_progress_estimate);
         Progress::messageProgress(Progress::Stage::INSET_SKIN, mesh_order_idx + 1, storage.meshes.size());
     }
 
-    unsigned int print_layer_count = 0;
     for (unsigned int layer_nr = 0; layer_nr < slice_layer_count; layer_nr++)
     {
         SliceLayer* layer = nullptr;
@@ -211,7 +249,6 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
             if (int(layer_nr) <= mesh.layer_nr_max_filled_layer)
             {
                 layer = &mesh.layers[layer_nr];
-                print_layer_count = layer_nr + 1;
                 break;
             }
         }
@@ -224,21 +261,21 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
         }
     }
 
-    log("Layer count: %i\n", print_layer_count);
+    log("Layer count: %i\n", storage.print_layer_count);
 
     //layerparts2HTML(storage, "output/output.html");
 
     Progress::messageProgressStage(Progress::Stage::SUPPORT, &time_keeper);
 
-    AreaSupport::generateSupportAreas(storage, print_layer_count);
+    AreaSupport::generateSupportAreas(storage, storage.print_layer_count);
 
     // we need to remove empty layers after we have procesed the insets
     // processInsets might throw away parts if they have no wall at all (cause it doesn't fit)
     // brim depends on the first layer not being empty
     // only remove empty layers if we haven't generate support, because then support was added underneath the model.
     //   for some materials it's better to print on support than on the buildplate.
-    removeEmptyFirstLayers(storage, getSettingInMicrons("layer_height"), print_layer_count); // changes total_layers!
-    if (print_layer_count == 0)
+    removeEmptyFirstLayers(storage, getSettingInMicrons("layer_height"), storage.print_layer_count); // changes storage.print_layer_count!
+    if (storage.print_layer_count == 0)
     {
         log("Stopping process because there are no non-empty layers.\n");
         return;
@@ -247,7 +284,7 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
     /*
     if (storage.support.generated)
     {
-        for (unsigned int layer_idx = 0; layer_idx < total_layers; layer_idx++)
+        for (unsigned int layer_idx = 0; layer_idx < storage.print_layer_count; layer_idx++)
         {
             Polygons& support = storage.support.supportLayers[layer_idx].supportAreas;
             ExtruderTrain* infill_extr = storage.meshgroup->getExtruderTrain(storage.getSettingAsIndex("support_infill_extruder_nr"));
@@ -256,15 +293,17 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
     }
     */
 
+    computePrintHeightStatistics(storage);
+
     // handle helpers
-    storage.primeTower.computePrimeTowerMax(storage);
-    storage.primeTower.generatePaths(storage, print_layer_count);
+    storage.primeTower.generatePaths(storage);
+    storage.primeTower.subtractFromSupport(storage);
     
     logDebug("Processing ooze shield\n");
     processOozeShield(storage);
 
     logDebug("Processing draft shield\n");
-    processDraftShield(storage, print_layer_count);
+    processDraftShield(storage);
 
     logDebug("Processing platform adhesion\n");
     processPlatformAdhesion(storage);
@@ -272,17 +311,18 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
     // meshes post processing
     for (SliceMeshStorage& mesh : storage.meshes)
     {
-        processDerivedWallsSkinInfill(mesh, print_layer_count);
+        processDerivedWallsSkinInfill(mesh);
     }
 }
 
-void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order, size_t total_layers, ProgressStageEstimator& inset_skin_progress_estimate)
+void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order, ProgressStageEstimator& inset_skin_progress_estimate)
 {
     unsigned int mesh_idx = mesh_order[mesh_order_idx];
     SliceMeshStorage& mesh = storage.meshes[mesh_idx];
+    size_t mesh_layer_count = mesh.layers.size();
     if (mesh.getSettingBoolean("infill_mesh"))
     {
-        processInfillMesh(storage, mesh_order_idx, mesh_order, total_layers);
+        processInfillMesh(storage, mesh_order_idx, mesh_order);
     }
     
     // TODO: make progress more accurate!!
@@ -292,20 +332,20 @@ void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage,
     
     inset_skin_progress_estimate.nextStage(mesh_inset_skin_progress_estimator); // the stage of this function call
     
-    ProgressEstimatorLinear* inset_estimator = new ProgressEstimatorLinear(total_layers);
+    ProgressEstimatorLinear* inset_estimator = new ProgressEstimatorLinear(mesh_layer_count);
     mesh_inset_skin_progress_estimator->nextStage(inset_estimator);
     
     
     // walls
-    for(unsigned int layer_number = 0; layer_number < total_layers; layer_number++)
+    for (unsigned int layer_number = 0; layer_number < mesh.layers.size(); layer_number++)
     {
-        logDebug("Processing insets for layer %i of %i\n", layer_number, total_layers);
+        logDebug("Processing insets for layer %i of %i\n", layer_number, mesh_layer_count);
         processInsets(mesh, layer_number);
         double progress = inset_skin_progress_estimate.progress(layer_number);
         Progress::messageProgress(Progress::Stage::INSET_SKIN, progress * 100, 100);
     }
 
-    ProgressEstimatorLinear* skin_estimator = new ProgressEstimatorLinear(total_layers);
+    ProgressEstimatorLinear* skin_estimator = new ProgressEstimatorLinear(mesh_layer_count);
     mesh_inset_skin_progress_estimator->nextStage(skin_estimator);
 
     bool process_infill = mesh.getSettingInMicrons("infill_line_distance") > 0;
@@ -333,9 +373,9 @@ void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage,
     {
         mesh_max_bottom_layer_count = std::max(mesh_max_bottom_layer_count, mesh.getSettingAsCount("bottom_layers"));
     }
-    for(unsigned int layer_number = 0; layer_number < total_layers; layer_number++)
+    for (unsigned int layer_number = 0; layer_number < mesh.layers.size(); layer_number++)
     {
-        logDebug("Processing skins and infill layer %i of %i\n", layer_number, total_layers);
+        logDebug("Processing skins and infill layer %i of %i\n", layer_number, mesh_layer_count);
         if (!mesh.getSettingBoolean("magic_spiralize") || static_cast<int>(layer_number) < mesh_max_bottom_layer_count)    //Only generate up/downskin and infill for the first X layers when spiralize is choosen.
         {
             processSkinsAndInfill(mesh, layer_number, process_infill);
@@ -345,7 +385,7 @@ void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage,
     }
 }
 
-void FffPolygonGenerator::processInfillMesh(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order, size_t total_layers)
+void FffPolygonGenerator::processInfillMesh(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order)
 {
     unsigned int mesh_idx = mesh_order[mesh_order_idx];
     SliceMeshStorage& mesh = storage.meshes[mesh_idx];
@@ -416,13 +456,19 @@ void FffPolygonGenerator::processInfillMesh(SliceDataStorage& storage, unsigned
     
 }
 
-void FffPolygonGenerator::processDerivedWallsSkinInfill(SliceMeshStorage& mesh, size_t total_layers)
+void FffPolygonGenerator::processDerivedWallsSkinInfill(SliceMeshStorage& mesh)
 {
     // create gradual infill areas
     SkinInfillAreaComputation::generateGradualInfill(mesh, mesh.getSettingInMicrons("gradual_infill_step_height"), mesh.getSettingAsCount("gradual_infill_steps"));
 
+    //SubDivCube Pre-compute Octree
+    if (mesh.getSettingAsFillMethod("infill_pattern") == EFillMethod::CUBICSUBDIV)
+    {
+        SubDivCube::precomputeOctree(mesh);
+    }
+
     // combine infill
-    unsigned int combined_infill_layers = std::max(1U, round_divide(mesh.getSettingInMicrons("infill_sparse_thickness"), std::max(getSettingInMicrons("layer_height"), 1))); //How many infill layers to combine to obtain the requested sparse thickness.
+    unsigned int combined_infill_layers = std::max(1U, round_divide(mesh.getSettingInMicrons("infill_sparse_thickness"), std::max(getSettingInMicrons("layer_height"), (coord_t)1))); //How many infill layers to combine to obtain the requested sparse thickness.
     combineInfillLayers(mesh,combined_infill_layers);
 
     // fuzzy skin
@@ -438,12 +484,14 @@ void FffPolygonGenerator::processInsets(SliceMeshStorage& mesh, unsigned int lay
     if (mesh.getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::SURFACE)
     {
         int inset_count = mesh.getSettingAsCount("wall_line_count");
-        if (mesh.getSettingBoolean("magic_spiralize") && static_cast<int>(layer_nr) < mesh.getSettingAsCount("bottom_layers") && layer_nr % 2 == 1)//Add extra insets every 2 layers when spiralizing, this makes bottoms of cups watertight.
+        if (mesh.getSettingBoolean("magic_spiralize") && static_cast<int>(layer_nr) < mesh.getSettingAsCount("bottom_layers") && ((layer_nr % 2) + 2) % 2 == 1)//Add extra insets every 2 layers when spiralizing, this makes bottoms of cups watertight.
             inset_count += 5;
         int line_width_x = mesh.getSettingInMicrons("wall_line_width_x");
         int line_width_0 = mesh.getSettingInMicrons("wall_line_width_0");
         if (mesh.getSettingBoolean("alternate_extra_perimeter"))
-            inset_count += layer_nr % 2; 
+        {
+            inset_count += ((layer_nr % 2) + 2) % 2;
+        }
         bool recompute_outline_based_on_outer_wall = mesh.getSettingBoolean("support_enable");
         WallsComputation walls_computation(mesh.getSettingInMicrons("wall_0_inset"), line_width_0, line_width_x, inset_count, recompute_outline_based_on_outer_wall);
         walls_computation.generateInsets(layer);
@@ -452,16 +500,19 @@ void FffPolygonGenerator::processInsets(SliceMeshStorage& mesh, unsigned int lay
 
 void FffPolygonGenerator::removeEmptyFirstLayers(SliceDataStorage& storage, const int layer_height, unsigned int& total_layers)
 {
-    // only remove empty layers if we haven't generate support, because then support was added underneath the model.
-    //   for some materials it's better to print on support than on the buildplate.
-    if (storage.support.generated)
-    {
-        return; // the first layer will have support and therefore not be empty
-    }
     int n_empty_first_layers = 0;
     for (unsigned int layer_idx = 0; layer_idx < total_layers; layer_idx++)
     { 
         bool layer_is_empty = true;
+        if (storage.support.generated && layer_idx < storage.support.supportLayers.size())
+        {
+            SupportLayer& support_layer = storage.support.supportLayers[layer_idx];
+            if (support_layer.supportAreas.size() > 0 || support_layer.skin.size() > 0)
+            {
+                layer_is_empty = false;
+                break;
+            }
+        }
         for (SliceMeshStorage& mesh : storage.meshes)
         {
             SliceLayer& layer = mesh.layers[layer_idx];
@@ -492,8 +543,12 @@ void FffPolygonGenerator::removeEmptyFirstLayers(SliceDataStorage& storage, cons
             {
                 layer.printZ -= n_empty_first_layers * layer_height;
             }
+            mesh.layer_nr_max_filled_layer -= n_empty_first_layers;
         }
         total_layers -= n_empty_first_layers;
+        storage.support.layer_nr_max_filled_layer -= n_empty_first_layers;
+        std::vector<SupportLayer>& support_layers = storage.support.supportLayers;
+        support_layers.erase(support_layers.begin(), support_layers.begin() + n_empty_first_layers);
     }
 }
   
@@ -521,6 +576,57 @@ void FffPolygonGenerator::processSkinsAndInfill(SliceMeshStorage& mesh, unsigned
     }
 }
 
+void FffPolygonGenerator::computePrintHeightStatistics(SliceDataStorage& storage)
+{
+    int extruder_count = storage.meshgroup->getExtruderCount();
+
+    std::vector<int>& max_print_height_per_extruder = storage.max_print_height_per_extruder;
+    assert(max_print_height_per_extruder.size() == 0 && "storage.max_print_height_per_extruder shouldn't have been initialized yet!");
+    max_print_height_per_extruder.resize(extruder_count, -1); //Initialize all as -1.
+    { // compute max_object_height_per_extruder
+        //Height of the meshes themselves.
+        for (SliceMeshStorage& mesh : storage.meshes)
+        {
+            if (mesh.getSettingBoolean("anti_overhang_mesh") || mesh.getSettingBoolean("support_mesh"))
+            {
+                continue; //Special type of mesh that doesn't get printed.
+            }
+            const unsigned int extr_nr = mesh.getSettingAsIndex("extruder_nr");
+            max_print_height_per_extruder[extr_nr] = std::max(max_print_height_per_extruder[extr_nr], mesh.layer_nr_max_filled_layer);
+        }
+
+        //Height of where the support reaches.
+        const unsigned int support_infill_extruder_nr = storage.getSettingAsIndex("support_infill_extruder_nr"); // TODO: support extruder should be configurable per object
+        max_print_height_per_extruder[support_infill_extruder_nr] =
+            std::max(max_print_height_per_extruder[support_infill_extruder_nr],
+                     storage.support.layer_nr_max_filled_layer);
+        const unsigned int support_skin_extruder_nr = storage.getSettingAsIndex("support_interface_extruder_nr"); // TODO: support skin extruder should be configurable per object
+        max_print_height_per_extruder[support_skin_extruder_nr] =
+            std::max(max_print_height_per_extruder[support_skin_extruder_nr],
+                     storage.support.layer_nr_max_filled_layer);
+
+        //Height of where the platform adhesion reaches.
+        if (storage.getSettingAsPlatformAdhesion("adhesion_type") != EPlatformAdhesion::NONE)
+        {
+            const unsigned int adhesion_extruder_nr = storage.getSettingAsIndex("adhesion_extruder_nr");
+            max_print_height_per_extruder[adhesion_extruder_nr] =
+                std::max(0, max_print_height_per_extruder[adhesion_extruder_nr]);
+        }
+    }
+
+    storage.max_print_height_order = order(max_print_height_per_extruder);
+    if (extruder_count >= 2)
+    {
+        int second_highest_extruder = storage.max_print_height_order[extruder_count - 2];
+        storage.max_print_height_second_to_last_extruder = max_print_height_per_extruder[second_highest_extruder];
+    }
+    else
+    {
+        storage.max_print_height_second_to_last_extruder = -1;
+    }
+}
+
+
 void FffPolygonGenerator::processOozeShield(SliceDataStorage& storage)
 {
     if (!getSettingBoolean("ooze_shield_enabled"))
@@ -530,7 +636,7 @@ void FffPolygonGenerator::processOozeShield(SliceDataStorage& storage)
 
     const int ooze_shield_dist = getSettingInMicrons("ooze_shield_dist");
 
-    for (int layer_nr = 0; layer_nr <= storage.max_object_height_second_to_last_extruder; layer_nr++)
+    for (int layer_nr = 0; layer_nr <= storage.max_print_height_second_to_last_extruder; layer_nr++)
     {
         storage.oozeShield.push_back(storage.getLayerOutlines(layer_nr, true).offset(ooze_shield_dist, ClipperLib::jtRound));
     }
@@ -539,26 +645,26 @@ void FffPolygonGenerator::processOozeShield(SliceDataStorage& storage)
     if (angle <= 89)
     {
         int allowed_angle_offset = tan(getSettingInAngleRadians("ooze_shield_angle")) * getSettingInMicrons("layer_height"); // Allow for a 60deg angle in the oozeShield.
-        for (int layer_nr = 1; layer_nr <= storage.max_object_height_second_to_last_extruder; layer_nr++)
+        for (int layer_nr = 1; layer_nr <= storage.max_print_height_second_to_last_extruder; layer_nr++)
         {
             storage.oozeShield[layer_nr] = storage.oozeShield[layer_nr].unionPolygons(storage.oozeShield[layer_nr - 1].offset(-allowed_angle_offset));
         }
-        for (int layer_nr = storage.max_object_height_second_to_last_extruder; layer_nr > 0; layer_nr--)
+        for (int layer_nr = storage.max_print_height_second_to_last_extruder; layer_nr > 0; layer_nr--)
         {
             storage.oozeShield[layer_nr - 1] = storage.oozeShield[layer_nr - 1].unionPolygons(storage.oozeShield[layer_nr].offset(-allowed_angle_offset));
         }
     }
 
     const float largest_printed_area = 1.0; // TODO: make var a parameter, and perhaps even a setting?
-    for (int layer_nr = 0; layer_nr <= storage.max_object_height_second_to_last_extruder; layer_nr++)
+    for (int layer_nr = 0; layer_nr <= storage.max_print_height_second_to_last_extruder; layer_nr++)
     {
         storage.oozeShield[layer_nr].removeSmallAreas(largest_printed_area);
     }
 }
 
-void FffPolygonGenerator::processDraftShield(SliceDataStorage& storage, unsigned int total_layers)
+void FffPolygonGenerator::processDraftShield(SliceDataStorage& storage)
 {
-    const unsigned int draft_shield_layers = getDraftShieldLayerCount(total_layers);
+    const unsigned int draft_shield_layers = getDraftShieldLayerCount(storage.print_layer_count);
     if (draft_shield_layers <= 0)
     {
         return;
@@ -568,7 +674,7 @@ void FffPolygonGenerator::processDraftShield(SliceDataStorage& storage, unsigned
     const unsigned int layer_skip = 500 / layer_height + 1;
 
     Polygons& draft_shield = storage.draft_protection_shield;
-    for (unsigned int layer_nr = 0; layer_nr < total_layers && layer_nr < draft_shield_layers; layer_nr += layer_skip)
+    for (unsigned int layer_nr = 0; layer_nr < storage.print_layer_count && layer_nr < draft_shield_layers; layer_nr += layer_skip)
     {
         draft_shield = draft_shield.unionPolygons(storage.getLayerOutlines(layer_nr, true));
     }
@@ -594,6 +700,8 @@ void FffPolygonGenerator::processPlatformAdhesion(SliceDataStorage& storage)
     case EPlatformAdhesion::RAFT:
         Raft::generate(storage, train->getSettingInMicrons("raft_margin"));
         break;
+    case EPlatformAdhesion::NONE:
+        break;
     }
 }
 

src/FffPolygonGenerator.h

@@ -84,10 +84,9 @@ private:
      * \param storage Input and Output parameter: fetches the outline information (see SliceLayerPart::outline) and generates the other reachable field of the \p storage
      * \param mesh_order_idx The index of the mesh_idx in \p mesh_order to process in the vector of meshes in \p storage
      * \param mesh_order The order in which the meshes are processed (used for infill meshes)
-     * \param total_layers The total number of layers over all objects
      * \param inset_skin_progress_estimate The progress stage estimate calculator
      */
-    void processBasicWallsSkinInfill(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order, size_t total_layers, ProgressStageEstimator& inset_skin_progress_estimate);
+    void processBasicWallsSkinInfill(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order, ProgressStageEstimator& inset_skin_progress_estimate);
     
     /*!
      * Process the mesh to be an infill mesh: limit all outlines to within the infill of normal meshes and subtract their volume from the infill of those meshes
@@ -95,18 +94,16 @@ private:
      * \param storage Input and Output parameter: fetches the outline information (see SliceLayerPart::outline) and generates the other reachable field of the \p storage
      * \param mesh_order_idx The index of the mesh_idx in \p mesh_order to process in the vector of meshes in \p storage
      * \param mesh_order The order in which the meshes are processed
-     * \param total_layers The total number of layers over all objects
      */
-    void processInfillMesh(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order, size_t total_layers);
+    void processInfillMesh(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order);
     
     /*!
      * Process features which are derived from the basic walls, skin, and infill:
      * fuzzy skin, infill combine
      * 
      * \param mesh Input and Output parameter: fetches the outline information (see SliceLayerPart::outline) and generates the other reachable field of the \p storage
-     * \param total_layers The total number of layers over all objects
      */
-    void processDerivedWallsSkinInfill(SliceMeshStorage& mesh, size_t total_layers);
+    void processDerivedWallsSkinInfill(SliceMeshStorage& mesh);
     
     /*!
      * Remove all bottom layers which are empty.
@@ -118,7 +115,14 @@ private:
      * \param total_layers The total number of layers
      */
     void removeEmptyFirstLayers(SliceDataStorage& storage, const int layer_height, unsigned int& total_layers);
-    
+
+    /*!
+     * Set \ref SliceDataStorage::max_print_height_per_extruder and \ref SliceDataStorage::max_print_height_order and \ref SliceDataStorage::max_print_height_second_to_last_extruder
+     * 
+     * \param[in,out] storage Where to retrieve mesh and support etc settings from and where the print height statistics are saved.
+     */
+    void computePrintHeightStatistics(SliceDataStorage& storage);
+
     /*!
      * Generate the inset polygons which form the walls.
      * \param mesh Input and Output parameter: fetches the outline information (see SliceLayerPart::outline) and generates the other reachable field of the \p storage
@@ -144,9 +148,8 @@ private:
      * Generate the polygons where the draft screen should be.
      * 
      * \param storage Input and Output parameter: fetches the outline information (see SliceLayerPart::outline) and generates the other reachable field of the \p storage
-     * \param total_layers The total number of layers 
      */
-    void processDraftShield(SliceDataStorage& storage, unsigned int total_layers);
+    void processDraftShield(SliceDataStorage& storage);
 
     /*!
      * Generate the skirt/brim/raft areas/insets.

src/FffProcessor.cpp

@@ -60,7 +60,7 @@ bool FffProcessor::processMeshGroup(MeshGroup* meshgroup)
     bool empty = true;
     for (Mesh& mesh : meshgroup->meshes)
     {
-        if (!mesh.getSettingBoolean("infill_mesh"))
+        if (!mesh.getSettingBoolean("infill_mesh") && !mesh.getSettingBoolean("anti_overhang_mesh"))
         {
             empty = false;
         }

src/LayerPlanBuffer.cpp

@@ -13,7 +13,7 @@ void LayerPlanBuffer::flush()
 {
     if (buffer.size() > 0)
     {
-        insertPreheatCommands(); // insert preheat commands of the very last layer
+        insertTempCommands(); // insert preheat commands of the very last layer
     }
     while (!buffer.empty())
     {
@@ -38,41 +38,51 @@ void LayerPlanBuffer::insertPreheatCommand(ExtruderPlan& extruder_plan_before, d
         if (acc_time > time_after_extruder_plan_start)
         {
             const double time_before_path_end = acc_time - time_after_extruder_plan_start;
-            extruder_plan_before.insertCommand(path_idx, extruder, temp, false, time_this_path - time_before_path_end);
+            bool wait = false;
+            extruder_plan_before.insertCommand(path_idx, extruder, temp, wait, time_this_path - time_before_path_end);
             return;
         }
     }
-    extruder_plan_before.insertCommand(0, extruder, temp, false); // insert at start of extruder plan if time_after_extruder_plan_start > extruder_plan.time
+    bool wait = false;
+    unsigned int path_idx = 0;
+    extruder_plan_before.insertCommand(path_idx, extruder, temp, wait); // insert at start of extruder plan if time_after_extruder_plan_start > extruder_plan.time
 }
 
 Preheat::WarmUpResult LayerPlanBuffer::timeBeforeExtruderPlanToInsert(std::vector<ExtruderPlan*>& extruder_plans, unsigned int extruder_plan_idx)
 {
     ExtruderPlan& extruder_plan = *extruder_plans[extruder_plan_idx];
     int extruder = extruder_plan.extruder;
-    double required_temp = extruder_plan.required_temp;
-    
+    double initial_print_temp = extruder_plan.initial_printing_temperature;
+
     double in_between_time = 0.0;
     for (unsigned int extruder_plan_before_idx = extruder_plan_idx - 1; int(extruder_plan_before_idx) >= 0; extruder_plan_before_idx--)
     { // find a previous extruder plan where the same extruder is used to see what time this extruder wasn't used
-        ExtruderPlan& extruder_plan = *extruder_plans[extruder_plan_before_idx];
-        if (extruder_plan.extruder == extruder)
+        ExtruderPlan& extruder_plan_before = *extruder_plans[extruder_plan_before_idx];
+        if (extruder_plan_before.extruder == extruder)
         {
-            Preheat::WarmUpResult warm_up = preheat_config.timeBeforeEndToInsertPreheatCommand_coolDownWarmUp(in_between_time, extruder, required_temp);
+            double temp_before = preheat_config.getFinalPrintTemp(extruder);
+            if (temp_before == 0)
+            {
+                temp_before = extruder_plan_before.printing_temperature;
+            }
+            constexpr bool during_printing = false;
+            Preheat::WarmUpResult warm_up = preheat_config.getWarmUpPointAfterCoolDown(in_between_time, extruder, temp_before, preheat_config.getStandbyTemp(extruder), initial_print_temp, during_printing);
             warm_up.heating_time = std::min(in_between_time, warm_up.heating_time + extra_preheat_time);
             return warm_up;
         }
-        in_between_time += extruder_plan.estimates.getTotalTime();
+        in_between_time += extruder_plan_before.estimates.getTotalTime();
     }
     // The last extruder plan with the same extruder falls outside of the buffer
     // assume the nozzle has cooled down to strandby temperature already.
     Preheat::WarmUpResult warm_up;
     warm_up.total_time_window = in_between_time;
     warm_up.lowest_temperature = preheat_config.getStandbyTemp(extruder);
-    warm_up.heating_time = preheat_config.timeBeforeEndToInsertPreheatCommand_warmUp(warm_up.lowest_temperature, extruder, required_temp, false);
+    constexpr bool during_printing = false;
+    warm_up.heating_time = preheat_config.getTimeToGoFromTempToTemp(extruder, warm_up.lowest_temperature, initial_print_temp, during_printing);
     if (warm_up.heating_time > in_between_time)
     {
         warm_up.heating_time = in_between_time;
-        warm_up.lowest_temperature = in_between_time / preheat_config.getTimeToHeatup1Degree(extruder);
+        warm_up.lowest_temperature = in_between_time / preheat_config.getTimeToHeatup1Degree(extruder, during_printing);
     }
     warm_up.heating_time = warm_up.heating_time + extra_preheat_time;
     return warm_up;
@@ -82,7 +92,8 @@ Preheat::WarmUpResult LayerPlanBuffer::timeBeforeExtruderPlanToInsert(std::vecto
 void LayerPlanBuffer::insertPreheatCommand_singleExtrusion(ExtruderPlan& prev_extruder_plan, int extruder, double required_temp)
 {
     // time_before_extruder_plan_end is halved, so that at the layer change the temperature will be half way betewen the two requested temperatures
-    double time_before_extruder_plan_end = 0.5 * preheat_config.timeBeforeEndToInsertPreheatCommand_warmUp(prev_extruder_plan.required_temp, extruder, required_temp, true);
+    constexpr bool during_printing = true;
+    double time_before_extruder_plan_end = 0.5 * preheat_config.getTimeToGoFromTempToTemp(extruder, prev_extruder_plan.printing_temperature, required_temp, during_printing);
     time_before_extruder_plan_end = std::min(prev_extruder_plan.estimates.getTotalTime(), time_before_extruder_plan_end);
 
     insertPreheatCommand(prev_extruder_plan, time_before_extruder_plan_end, extruder, required_temp);
@@ -111,13 +122,13 @@ void LayerPlanBuffer::insertPreheatCommand_multiExtrusion(std::vector<ExtruderPl
 {
     ExtruderPlan& extruder_plan = *extruder_plans[extruder_plan_idx];
     int extruder = extruder_plan.extruder;
-    double required_temp = extruder_plan.required_temp;
+    double initial_print_temp = extruder_plan.initial_printing_temperature;
     
     Preheat::WarmUpResult heating_time_and_from_temp = timeBeforeExtruderPlanToInsert(extruder_plans, extruder_plan_idx);
 
     if (heating_time_and_from_temp.total_time_window < preheat_config.getMinimalTimeWindow(extruder))
     {
-        handleStandbyTemp(extruder_plans, extruder_plan_idx, required_temp);
+        handleStandbyTemp(extruder_plans, extruder_plan_idx, initial_print_temp);
         return; // don't insert preheat command and just stay on printing temperature
     }
     else
@@ -125,30 +136,32 @@ void LayerPlanBuffer::insertPreheatCommand_multiExtrusion(std::vector<ExtruderPl
         handleStandbyTemp(extruder_plans, extruder_plan_idx, heating_time_and_from_temp.lowest_temperature);
     }
 
+    // handle preheat command
     double time_before_extruder_plan_to_insert = heating_time_and_from_temp.heating_time;
     for (unsigned int extruder_plan_before_idx = extruder_plan_idx - 1; int(extruder_plan_before_idx) >= 0; extruder_plan_before_idx--)
     {
         ExtruderPlan& extruder_plan_before = *extruder_plans[extruder_plan_before_idx];
         assert (extruder_plan_before.extruder != extruder);
-        
+
         double time_here = extruder_plan_before.estimates.getTotalTime();
         if (time_here >= time_before_extruder_plan_to_insert)
         {
-            insertPreheatCommand(extruder_plan_before, time_before_extruder_plan_to_insert, extruder, required_temp);
+            insertPreheatCommand(extruder_plan_before, time_before_extruder_plan_to_insert, extruder, initial_print_temp);
             return;
         }
         time_before_extruder_plan_to_insert -= time_here;
     }
-    
+
     // time_before_extruder_plan_to_insert falls before all plans in the buffer
-    extruder_plans[0]->insertCommand(0, extruder, required_temp, false); // insert preheat command at verfy beginning of buffer
+    bool wait = false;
+    unsigned int path_idx = 0;
+    extruder_plans[0]->insertCommand(path_idx, extruder, initial_print_temp, wait); // insert preheat command at verfy beginning of buffer
 }
 
-void LayerPlanBuffer::insertPreheatCommand(std::vector<ExtruderPlan*>& extruder_plans, unsigned int extruder_plan_idx)
+void LayerPlanBuffer::insertTempCommands(std::vector<ExtruderPlan*>& extruder_plans, unsigned int extruder_plan_idx)
 {   
     ExtruderPlan& extruder_plan = *extruder_plans[extruder_plan_idx];
     int extruder = extruder_plan.extruder;
-    double required_temp = extruder_plan.required_temp;
     
     
     ExtruderPlan* prev_extruder_plan = extruder_plans[extruder_plan_idx - 1];
@@ -162,19 +175,154 @@ void LayerPlanBuffer::insertPreheatCommand(std::vector<ExtruderPlan*>& extruder_
     
     if (prev_extruder == extruder)
     {
-        if (preheat_config.usesFlowDependentTemp(extruder))
-        {
-            insertPreheatCommand_singleExtrusion(*prev_extruder_plan, extruder, required_temp);
-        }
+        insertPreheatCommand_singleExtrusion(*prev_extruder_plan, extruder, extruder_plan.printing_temperature);
+        prev_extruder_plan->printing_temperature_command = --prev_extruder_plan->inserts.end();
     }
     else 
     {
         insertPreheatCommand_multiExtrusion(extruder_plans, extruder_plan_idx);
+        insertFinalPrintTempCommand(extruder_plans, extruder_plan_idx - 1);
+        insertPrintTempCommand(extruder_plan);
     }
-    
 }
 
-void LayerPlanBuffer::insertPreheatCommands()
+void LayerPlanBuffer::insertPrintTempCommand(ExtruderPlan& extruder_plan)
+{
+    unsigned int extruder = extruder_plan.extruder;
+    double print_temp = extruder_plan.printing_temperature;
+
+    double heated_pre_travel_time = 0;
+    if (preheat_config.getInitialPrintTemp(extruder) != 0)
+    { // handle heating from initial_print_temperature to printing_tempreature
+        unsigned int path_idx;
+        for (path_idx = 0; path_idx < extruder_plan.paths.size(); path_idx++)
+        {
+            GCodePath& path = extruder_plan.paths[path_idx];
+            heated_pre_travel_time += path.estimates.getTotalTime();
+            if (!path.isTravelPath())
+            {
+                break;
+            }
+        }
+        bool wait = false;
+        extruder_plan.insertCommand(path_idx, extruder, print_temp, wait);
+    }
+    extruder_plan.heated_pre_travel_time = heated_pre_travel_time;
+}
+
+void LayerPlanBuffer::insertFinalPrintTempCommand(std::vector<ExtruderPlan*>& extruder_plans, unsigned int last_extruder_plan_idx)
+{
+    ExtruderPlan& last_extruder_plan = *extruder_plans[last_extruder_plan_idx];
+    int extruder = last_extruder_plan.extruder;
+
+    double final_print_temp = preheat_config.getFinalPrintTemp(extruder);
+    if (final_print_temp == 0)
+    {
+        return;
+    }
+
+    double heated_post_travel_time = 0; // The time after the last extrude move toward the end of the extruder plan during which the nozzle is stable at the final print temperature
+    { // compute heated_post_travel_time
+        unsigned int path_idx;
+        for (path_idx = last_extruder_plan.paths.size() - 1; int(path_idx) >= 0; path_idx--)
+        {
+            GCodePath& path = last_extruder_plan.paths[path_idx];
+            if (!path.isTravelPath())
+            {
+                break;
+            }
+            heated_post_travel_time += path.estimates.getTotalTime();
+        }
+    }
+
+    double time_window = 0; // The time window within which the nozzle needs to heat from the initial print temp to the printing temperature and then back to the final print temp; i.e. from the first to the last extrusion move with this extruder
+    double weighted_average_print_temp = 0; // The average of the normal printing temperatures of the extruder plans (which might be different due to flow dependent temp or due to initial layer temp) Weighted by time
+    double initial_print_temp = -1; // The initial print temp of the first extruder plan with this extruder
+    { // compute time window and print temp statistics
+        double heated_pre_travel_time = -1; // The time before the first extrude move from the start of the extruder plan during which the nozzle is stable at the initial print temperature
+        for (unsigned int prev_extruder_plan_idx = last_extruder_plan_idx; (int)prev_extruder_plan_idx >= 0; prev_extruder_plan_idx--)
+        {
+            ExtruderPlan& prev_extruder_plan = *extruder_plans[prev_extruder_plan_idx];
+            if (prev_extruder_plan.extruder != extruder)
+            {
+                break;
+            }
+            double prev_extruder_plan_time = prev_extruder_plan.estimates.getTotalTime();
+            time_window += prev_extruder_plan_time;
+            heated_pre_travel_time = prev_extruder_plan.heated_pre_travel_time;
+
+            if (prev_extruder_plan.estimates.getTotalUnretractedTime() > 0)
+            { // handle temp statistics
+                assert(prev_extruder_plan.printing_temperature != -1 && "Previous extruder plan should already have a temperature planned");
+                weighted_average_print_temp += prev_extruder_plan.printing_temperature * prev_extruder_plan_time;
+                initial_print_temp = prev_extruder_plan.initial_printing_temperature;
+            }
+        }
+        weighted_average_print_temp /= time_window;
+        time_window -= heated_pre_travel_time + heated_post_travel_time;
+        assert(heated_pre_travel_time != -1 && "heated_pre_travel_time must have been computed; there must have been an extruder plan!");
+    }
+
+    assert((time_window >= 0 || last_extruder_plan.estimates.getMaterial() == 0) && "Time window should always be positive if we actually extrude");
+
+    //          ,layer change                                                                                   .
+    //          :     ,precool command                   ,layer change                                          .
+    //          : ____:                                  :     ,precool command                                 .
+    //          :/    \                             _____:_____:                                                .
+    //     _____/      \                           /           \                                                .
+    //    /             \                         /             \                                               .
+    //   /                                       /                                                              .
+    //  /                                       /                                                               .
+    //                                                                                                          .
+    // approximate ^               by                   ^                                                       .
+    // This approximation is quite ok since it only determines where to insert the precool temp command,
+    // which means the stable temperature of the previous extruder plan and the stable temperature of the next extruder plan couldn't be reached
+    constexpr bool during_printing = true;
+    Preheat::CoolDownResult warm_cool_result = preheat_config.getCoolDownPointAfterWarmUp(time_window, extruder, initial_print_temp, weighted_average_print_temp, final_print_temp, during_printing);
+    double cool_down_time = warm_cool_result.cooling_time;
+    assert(cool_down_time >= 0);
+
+    // find extruder plan in which to insert cooling command
+    ExtruderPlan* precool_extruder_plan = &last_extruder_plan;
+    {
+        for (unsigned int precool_extruder_plan_idx = last_extruder_plan_idx; (int)precool_extruder_plan_idx >= 0; precool_extruder_plan_idx--)
+        {
+            precool_extruder_plan = extruder_plans[precool_extruder_plan_idx];
+            if (precool_extruder_plan->printing_temperature_command)
+            { // the precool command ends up before the command to go to the print temperature of the next extruder plan, so remove that print temp command
+                precool_extruder_plan->inserts.erase(*precool_extruder_plan->printing_temperature_command);
+            }
+            double time_here = precool_extruder_plan->estimates.getTotalTime();
+            if (cool_down_time < time_here)
+            {
+                break;
+            }
+            cool_down_time -= time_here;
+        }
+    }
+
+    // at this point cool_down_time is what time is left if cool down time of extruder plans after precool_extruder_plan (up until last_extruder_plan) are already taken into account
+
+    { // insert temp command in precool_extruder_plan
+        double extrusion_time_seen = 0;
+        unsigned int path_idx;
+        for (path_idx = precool_extruder_plan->paths.size() - 1; int(path_idx) >= 0; path_idx--)
+        {
+            GCodePath& path = precool_extruder_plan->paths[path_idx];
+            extrusion_time_seen += path.estimates.getTotalTime();
+            if (extrusion_time_seen >= cool_down_time)
+            {
+                break;
+            }
+        }
+        bool wait = false;
+        double time_after_path_start = extrusion_time_seen - cool_down_time;
+        precool_extruder_plan->insertCommand(path_idx, extruder, final_print_temp, wait, time_after_path_start);
+    }
+}
+
+
+void LayerPlanBuffer::insertTempCommands()
 {
     if (buffer.back().extruder_plans.size() == 0 || (buffer.back().extruder_plans.size() == 1 && buffer.back().extruder_plans[0].paths.size() == 0))
     { // disregard empty layer
@@ -197,17 +345,27 @@ void LayerPlanBuffer::insertPreheatCommands()
     GCodePlanner& layer_plan = buffer.back();
     for (unsigned int extruder_plan_idx = 0; extruder_plan_idx < layer_plan.extruder_plans.size(); extruder_plan_idx++)
     {
+        unsigned int overall_extruder_plan_idx = extruder_plans.size() - layer_plan.extruder_plans.size() + extruder_plan_idx;
         ExtruderPlan& extruder_plan = layer_plan.extruder_plans[extruder_plan_idx];
+        int extruder = extruder_plan.extruder;
         double time = extruder_plan.estimates.getTotalUnretractedTime();
-        if (time <= 0.0 
-            || extruder_plan.estimates.getMaterial() == 0.0 // extruder plan only consists of moves (when an extruder switch occurs at the beginning of a layer)
-        )
+        if (time <= 0.0)
         {
             continue;
         }
         
-        double avg_flow = extruder_plan.estimates.getMaterial() / time; // TODO: subtract retracted travel time
-        extruder_plan.required_temp = preheat_config.getTemp(extruder_plan.extruder, avg_flow);
+        double avg_flow = extruder_plan.estimates.getMaterial() / time;
+        extruder_plan.printing_temperature = preheat_config.getTemp(extruder, avg_flow, extruder_plan.is_initial_layer);
+        extruder_plan.initial_printing_temperature = preheat_config.getInitialPrintTemp(extruder);
+        if (extruder_plan.initial_printing_temperature == 0
+            || !extruder_used_in_meshgroup[extruder]
+            || (overall_extruder_plan_idx > 0 && extruder_plans[overall_extruder_plan_idx - 1]->extruder == extruder)
+        )
+        {
+            extruder_plan.initial_printing_temperature = extruder_plan.printing_temperature;
+            extruder_used_in_meshgroup[extruder] = true;
+        }
+        assert(extruder_plan.printing_temperature != -1 && "extruder_plan.printing_temperature should now have been set");
 
         if (buffer.size() == 1 && extruder_plan_idx == 0)
         { // the very first extruder plan of the current meshgroup
@@ -221,7 +379,7 @@ void LayerPlanBuffer::insertPreheatCommands()
                     // see  FffGcodeWriter::processStartingCode
                     if (extruder_idx == extruder)
                     {
-                        gcode.setInitialTemp(extruder_idx, extruder_plan.required_temp);
+                        gcode.setInitialTemp(extruder_idx, extruder_plan.printing_temperature);
                     }
                     else 
                     {
@@ -239,8 +397,7 @@ void LayerPlanBuffer::insertPreheatCommands()
             continue;
         }
 
-        unsigned int overall_extruder_plan_idx = extruder_plans.size() - layer_plan.extruder_plans.size() + extruder_plan_idx;
-        insertPreheatCommand(extruder_plans, overall_extruder_plan_idx);
+        insertTempCommands(extruder_plans, overall_extruder_plan_idx);
     }
 }
 

src/LayerPlanBuffer.h

@@ -16,6 +16,19 @@
 namespace cura 
 {
 
+/*!
+ * Class for buffering multiple layer plans (\ref GCodePlanner) / extruder plans within those layer plans, so that temperature commands can be inserted in earlier layer plans.
+ * 
+ * This class handles where to insert temperature commands for:
+ * - initial layer temperature
+ * - flow dependent temperature
+ * - starting to heat up from the standby temperature
+ * - initial printing temperature | printing temperature | final printing temperature
+ * 
+ * \image html assets/precool.png "Temperature Regulation" width=10cm
+ * \image latex assets/precool.png "Temperature Regulation" width=10cm
+ * 
+ */
 class LayerPlanBuffer : SettingsMessenger
 {
     GCodeExport& gcode;
@@ -27,12 +40,14 @@ class LayerPlanBuffer : SettingsMessenger
 
     static constexpr const double extra_preheat_time = 1.0; //!< Time to start heating earlier than computed to avoid accummulative discrepancy between actual heating times and computed ones.
 
+    std::vector<bool> extruder_used_in_meshgroup; //!< For each extruder whether it has already been planned once in this meshgroup. This is used to see whether we should heat to the initial_print_temp or to the printing_temperature
 public:
     std::list<GCodePlanner> buffer; //!< The buffer containing several layer plans (GCodePlanner) before writing them to gcode.
     
     LayerPlanBuffer(SettingsBaseVirtual* settings, GCodeExport& gcode)
     : SettingsMessenger(settings)
     , gcode(gcode)
+    , extruder_used_in_meshgroup(MAX_EXTRUDERS, false)
     { }
     
     void setPreheatConfig(MeshGroup& settings)
@@ -49,7 +64,7 @@ public:
     {
         if (buffer.size() > 0)
         {
-            insertPreheatCommands(); // insert preheat commands of the just completed layer plan (not the newly emplaced one)
+            insertTempCommands(); // insert preheat commands of the just completed layer plan (not the newly emplaced one)
         }
         buffer.emplace_back(constructor_args...);
         if (buffer.size() > buffer_size)
@@ -68,7 +83,8 @@ public:
      * Write all remaining layer plans (GCodePlanner) to gcode and empty the buffer.
      */
     void flush();
-    
+
+private:
     /*!
      * Insert the preheat command for @p extruder into @p extruder_plan_before
      * 
@@ -118,13 +134,34 @@ public:
      * \param extruder_plans The extruder plans in the buffer, moved to a temporary vector (from lower to upper layers)
      * \param extruder_plan_idx The index of the extruder plan in \p extruder_plans for which to generate the preheat command
      */
-    void insertPreheatCommand(std::vector<ExtruderPlan*>& extruder_plans, unsigned int extruder_plan_idx);
+    void insertTempCommands(std::vector<ExtruderPlan*>& extruder_plans, unsigned int extruder_plan_idx);
+
+    /*!
+     * Insert the temperature command to heat from the initial print temperature to the printing temperature
+     * 
+     * The temperature command is insert at the start of the very first extrusion move
+     * 
+     * \param extruder_plan The extruder plan in which to insert the heat up command
+     */
+    void insertPrintTempCommand(ExtruderPlan& extruder_plan);
+
+    /*!
+     * Insert the temp command to start cooling from the printing temperature to the final print temp
+     * 
+     * The print temp is inserted before the last extrusion move of the extruder plan corresponding to \p last_extruder_plan_idx
+     * 
+     * The command is inserted at a timed offset before the end of the last extrusion move
+     * 
+     * \param extruder_plans The extruder plans in the buffer, moved to a temporary vector (from lower to upper layers)
+     * \param last_extruder_plan_idx The index of the last extruder plan in \p extruder_plans with the same extruder as previous extruder plans
+     */
+    void insertFinalPrintTempCommand(std::vector<ExtruderPlan*>& extruder_plans, unsigned int last_extruder_plan_idx);
 
     /*!
      * Insert the preheat commands for the last added layer (unless that layer was empty)
      */
-    void insertPreheatCommands();
-private:
+    void insertTempCommands();
+
     /*!
      * Reconfigure the standby temperature during which we didn't print with this extruder.
      * Find the previous extruder plan with the same extruder as layers[layer_plan_idx].extruder_plans[extruder_plan_idx]

src/MeshGroup.cpp

@@ -58,6 +58,7 @@ int MeshGroup::getExtruderCount() const
 
 ExtruderTrain* MeshGroup::createExtruderTrain(unsigned int extruder_nr)
 {
+    assert((int)extruder_nr >= 0 && (int)extruder_nr < getSettingAsCount("machine_extruder_count") && "only valid extruder trains may be requested!");
     if (!extruders[extruder_nr])
     {
         extruders[extruder_nr] = new ExtruderTrain(this, extruder_nr);
@@ -133,7 +134,7 @@ void MeshGroup::finalize()
     {
         createExtruderTrain(extruder_nr); // create it if it didn't exist yet
 
-        if (getSettingAsIndex("adhesion_extruder_nr") == extruder_nr)
+        if (getSettingAsIndex("adhesion_extruder_nr") == extruder_nr && getSettingAsPlatformAdhesion("adhesion_type") != EPlatformAdhesion::NONE)
         {
             getExtruderTrain(extruder_nr)->setIsUsed(true);
             continue;
@@ -157,7 +158,12 @@ void MeshGroup::finalize()
 
     for (const Mesh& mesh : meshes)
     {
-        getExtruderTrain(mesh.getSettingAsIndex("extruder_nr"))->setIsUsed(true);
+        if (!mesh.getSettingBoolean("anti_overhang_mesh")
+            && !mesh.getSettingBoolean("support_mesh")
+        )
+        {
+            getExtruderTrain(mesh.getSettingAsIndex("extruder_nr"))->setIsUsed(true);
+        }
     }
 
     //If the machine settings have been supplied, offset the given position vertices to the center of vertices (0,0,0) is at the bed center.

src/Preheat.cpp

@@ -0,0 +1,184 @@
+#include "Preheat.h"
+
+namespace cura 
+{
+
+void Preheat::setConfig(const MeshGroup& meshgroup)
+{
+    for (int extruder_nr = 0; extruder_nr < meshgroup.getExtruderCount(); extruder_nr++)
+    {
+        assert(meshgroup.getExtruderTrain(extruder_nr) != nullptr);
+        const ExtruderTrain& extruder_train = *meshgroup.getExtruderTrain(extruder_nr);
+        config_per_extruder.emplace_back();
+        Config& config = config_per_extruder.back();
+        double machine_nozzle_cool_down_speed = extruder_train.getSettingInSeconds("machine_nozzle_cool_down_speed");
+        double machine_nozzle_heat_up_speed = extruder_train.getSettingInSeconds("machine_nozzle_heat_up_speed");
+        double material_extrusion_cool_down_speed = extruder_train.getSettingInSeconds("material_extrusion_cool_down_speed");
+        assert(material_extrusion_cool_down_speed < machine_nozzle_heat_up_speed && "The extrusion cooldown speed must be smaller than the heat up speed; otherwise the printing temperature cannot be reached!");
+        config.time_to_cooldown_1_degree[0] = 1.0 / machine_nozzle_cool_down_speed;
+        config.time_to_heatup_1_degree[0] = 1.0 / machine_nozzle_heat_up_speed;
+        config.time_to_cooldown_1_degree[1] = 1.0 / (machine_nozzle_cool_down_speed + material_extrusion_cool_down_speed);
+        config.time_to_heatup_1_degree[1] = 1.0 / (machine_nozzle_heat_up_speed - material_extrusion_cool_down_speed);
+        config.standby_temp = extruder_train.getSettingInSeconds("material_standby_temperature");
+
+        config.min_time_window = extruder_train.getSettingInSeconds("machine_min_cool_heat_time_window");
+
+        config.material_print_temperature = extruder_train.getSettingInDegreeCelsius("material_print_temperature");
+        config.material_print_temperature_layer_0 = extruder_train.getSettingInDegreeCelsius("material_print_temperature_layer_0");
+        config.material_initial_print_temperature = extruder_train.getSettingInDegreeCelsius("material_initial_print_temperature");
+        config.material_final_print_temperature = extruder_train.getSettingInDegreeCelsius("material_final_print_temperature");
+
+        config.flow_dependent_temperature = extruder_train.getSettingBoolean("material_flow_dependent_temperature"); 
+
+        config.flow_temp_graph = extruder_train.getSettingAsFlowTempGraph("material_flow_temp_graph"); // [[0.1,180],[20,230]]
+    }
+}
+
+double Preheat::getTimeToGoFromTempToTemp(int extruder, double temp_before, double temp_after, bool during_printing)
+{
+    Config& config = config_per_extruder[extruder];
+    double time;
+    if (temp_after > temp_before)
+    {
+        time = (temp_after - temp_before) * config.time_to_heatup_1_degree[during_printing];
+    }
+    else
+    {
+        time = (temp_before - temp_after) * config.time_to_cooldown_1_degree[during_printing];
+    }
+    return std::max(0.0, time);
+}
+
+double Preheat::getTemp(unsigned int extruder, double flow, bool is_initial_layer)
+{
+    if (is_initial_layer && config_per_extruder[extruder].material_print_temperature_layer_0 != 0)
+    {
+        return config_per_extruder[extruder].material_print_temperature_layer_0;
+    }
+    return config_per_extruder[extruder].flow_temp_graph.getTemp(flow, config_per_extruder[extruder].material_print_temperature, config_per_extruder[extruder].flow_dependent_temperature);
+}
+
+Preheat::WarmUpResult Preheat::getWarmUpPointAfterCoolDown(double time_window, unsigned int extruder, double temp_start, double temp_mid, double temp_end, bool during_printing)
+{
+    WarmUpResult result;
+    const Config& config = config_per_extruder[extruder];
+    double time_to_cooldown_1_degree = config.time_to_cooldown_1_degree[during_printing];
+    double time_to_heatup_1_degree = config.time_to_heatup_1_degree[during_printing];
+    result.total_time_window = time_window;
+
+    //                    ,temp_end
+    //                   /                                    .
+    //     ,temp_start  /                                     .
+    //      \ ' ' ' ' '/ ' ' '> outer_temp                    .
+    //       \________/                                       .
+    //               "-> temp_mid
+    //      ^^^^^^^^^^
+    //      limited_time_window
+    double outer_temp;
+    double limited_time_window;
+    if (temp_start < temp_end)
+    { // extra time needed during heating
+        double extra_heatup_time = (temp_end - temp_start) * time_to_heatup_1_degree;
+        result.heating_time = extra_heatup_time;
+        limited_time_window = time_window - extra_heatup_time;
+        outer_temp = temp_start;
+    }
+    else
+    {
+        double extra_cooldown_time = (temp_start - temp_end) * time_to_cooldown_1_degree;
+        result.heating_time = 0;
+        limited_time_window = time_window - extra_cooldown_time;
+        outer_temp = temp_end;
+    }
+    if (limited_time_window < 0.0)
+    {
+        result.heating_time = 0.0;
+        result.lowest_temperature = std::min(temp_start, temp_end);
+        return result;
+    }
+
+    double time_ratio_cooldown_heatup = time_to_cooldown_1_degree / time_to_heatup_1_degree;
+    double time_to_heat_from_standby_to_print_temp = getTimeToGoFromTempToTemp(extruder, temp_mid, outer_temp, during_printing);
+    double time_needed_to_reach_standby_temp = time_to_heat_from_standby_to_print_temp * (1.0 + time_ratio_cooldown_heatup);
+    if (time_needed_to_reach_standby_temp < limited_time_window)
+    {
+        result.heating_time += time_to_heat_from_standby_to_print_temp;
+        result.lowest_temperature = temp_mid;
+    }
+    else 
+    {
+        result.heating_time += limited_time_window * time_to_heatup_1_degree / (time_to_cooldown_1_degree + time_to_heatup_1_degree);
+        result.lowest_temperature = std::max(temp_mid, temp_end - result.heating_time / time_to_heatup_1_degree);
+    }
+
+    if (result.heating_time > time_window || result.heating_time < 0.0)
+    {
+        logWarning("getWarmUpPointAfterCoolDown returns result outside of the time window!");
+    }
+    return result;
+}
+
+Preheat::CoolDownResult Preheat::getCoolDownPointAfterWarmUp(double time_window, unsigned int extruder, double temp_start, double temp_mid, double temp_end, bool during_printing)
+{
+    CoolDownResult result;
+    const Config& config = config_per_extruder[extruder];
+    double time_to_cooldown_1_degree = config.time_to_cooldown_1_degree[during_printing];
+    double time_to_heatup_1_degree = config.time_to_heatup_1_degree[during_printing];
+
+    assert(temp_start != -1 && temp_mid != -1 && temp_end != -1 && "temperatures must be initialized!");
+
+    result.total_time_window = time_window;
+
+    //      limited_time_window
+    //     :^^^^^^^^^^^^:
+    //     :  ________. : . . .> temp_mid
+    //     : /        \ :                                     .
+    //     :/ . . . . .\:. . .> outer_temp                    .
+    //     ^temp_start  \                                     .
+    //                   \                                    .
+    //                    ^temp_end
+    double outer_temp;
+    double limited_time_window;
+    if (temp_start < temp_end)
+    { // extra time needed during heating
+        double extra_heatup_time = (temp_end - temp_start) * time_to_heatup_1_degree;
+        result.cooling_time = 0;
+        limited_time_window = time_window - extra_heatup_time;
+        outer_temp = temp_end;
+    }
+    else
+    {
+        double extra_cooldown_time = (temp_start - temp_end) * time_to_cooldown_1_degree;
+        result.cooling_time = extra_cooldown_time;
+        limited_time_window = time_window - extra_cooldown_time;
+        outer_temp = temp_start;
+    }
+    if (limited_time_window < 0.0)
+    {
+        result.cooling_time = 0.0;
+        result.highest_temperature = std::max(temp_start, temp_end);
+        return result;
+    }
+    double time_ratio_cooldown_heatup = time_to_cooldown_1_degree / time_to_heatup_1_degree;
+    double cool_down_time = getTimeToGoFromTempToTemp(extruder, temp_mid, outer_temp, during_printing);
+    double time_needed_to_reach_temp1 = cool_down_time * (1.0 + time_ratio_cooldown_heatup);
+    if (time_needed_to_reach_temp1 < limited_time_window)
+    {
+        result.cooling_time += cool_down_time;
+        result.highest_temperature = temp_mid;
+    }
+    else 
+    {
+        result.cooling_time += limited_time_window * time_to_heatup_1_degree / (time_to_cooldown_1_degree + time_to_heatup_1_degree);
+        result.highest_temperature = std::min(temp_mid, temp_end + result.cooling_time / time_to_cooldown_1_degree);
+    }
+
+    if (result.cooling_time > time_window || result.cooling_time < 0.0)
+    {
+        logWarning("getCoolDownPointAfterWarmUp returns result outside of the time window!");
+    }
+    return result;
+}
+
+
+}//namespace cura

src/Preheat.h

@@ -26,17 +26,21 @@ class Preheat
     class Config
     {
     public:
-        double time_to_heatup_1_degree; //!< average time it takes to heat up one degree (in the range of normal print temperatures and standby temperature)
-        double time_to_cooldown_1_degree; //!< average time it takes to cool down one degree (in the range of normal print temperatures and standby temperature)
-        
-        double heatup_cooldown_time_mod_while_printing; //!< The time to be added to Preheat::time_to_heatup_1_degree and subtracted from Preheat::time_to_cooldown_1_degree to get the timings while printing
+        double time_to_heatup_1_degree[2]; //!< average time it takes to heat up one degree (in the range of normal print temperatures and standby temperature), while not-printing and while printing
+        double time_to_cooldown_1_degree[2]; //!< average time it takes to cool down one degree (in the range of normal print temperatures and standby temperature), while not-printing and while printing
 
         double standby_temp; //!< The temperature at which the nozzle rests when it is not printing.
 
         double min_time_window; //!< Minimal time (in seconds) to allow an extruder to cool down and then warm up again.
 
         double material_print_temperature; //!< default print temp (backward compatilibily)
-        
+
+        double material_print_temperature_layer_0; //!< initial layer print temp
+
+        double material_initial_print_temperature; //!< print temp when first starting to extrude after a layer switch
+
+        double material_final_print_temperature; //!< print temp at the end of all extrusion moves of an extruder to which it's cooled down just before - during the extrusion
+
         bool flow_dependent_temperature; //!< Whether to make the temperature dependent on flow
     
         FlowTempGraph flow_temp_graph; //!< The graph linking flows to corresponding temperatures
@@ -54,6 +58,16 @@ public:
         double lowest_temperature; //!< The lower temperature from which heating starts.
     };
 
+    /*!
+     * The type of result when computing when to start cooling down a nozzle before it's not going to be used again.
+     */
+    struct CoolDownResult
+    {
+        double total_time_window; //!< The total time in which heating and cooling takes place.
+        double cooling_time; //!< The total time needed to cool down to the required temperature.
+        double highest_temperature; //!< The upper temperature from which cooling starts.
+    };
+
     /*!
      * Get the standby temperature of an extruder train
      * \param extruder the extruder train for which to get the standby tmep
@@ -68,68 +82,51 @@ public:
      * Get the time it takes to heat up one degree celsius
      * 
      * \param extruder the extruder train for which to get time it takes to heat up one degree celsius
+     * \param during_printing whether the heating takes time during printing or when idle
      * \return the time it takes to heat up one degree celsius
      */
-    double getTimeToHeatup1Degree(int extruder)
+    double getTimeToHeatup1Degree(int extruder, bool during_printing)
     {
-        return config_per_extruder[extruder].time_to_heatup_1_degree;
+        return config_per_extruder[extruder].time_to_heatup_1_degree[during_printing];
+    }
+
+    /*!
+     * Get the initial print temperature when starting to extrude.
+     * \param during_printing whether the heating takes time during printing or when idle
+     */
+    double getInitialPrintTemp(int extruder)
+    {
+        return config_per_extruder[extruder].material_initial_print_temperature;
+    }
+
+    /*!
+     * Get the final print temperature at the end of all extrusion moves with the current extruder
+     */
+    double getFinalPrintTemp(int extruder)
+    {
+        return config_per_extruder[extruder].material_final_print_temperature;
     }
 
     /*!
      * Set the nozzle and material temperature settings for each extruder train.
+     * \param meshgroup Where to get settings from
      */
-    void setConfig(MeshGroup& settings)
-    {
-        for (int extruder_nr = 0; extruder_nr < settings.getExtruderCount(); extruder_nr++)
-        {
-            assert(settings.getExtruderTrain(extruder_nr) != nullptr);
-            ExtruderTrain& extruder_train = *settings.getExtruderTrain(extruder_nr);
-            config_per_extruder.emplace_back();
-            Config& config = config_per_extruder.back();
-            config.time_to_cooldown_1_degree = 1.0 / extruder_train.getSettingInSeconds("machine_nozzle_cool_down_speed"); // 0.5
-            config.time_to_heatup_1_degree = 1.0 / extruder_train.getSettingInSeconds("machine_nozzle_heat_up_speed"); // 0.5
-            config.heatup_cooldown_time_mod_while_printing = 1.0 / extruder_train.getSettingInSeconds("material_extrusion_cool_down_speed"); // 0.1
-            config.standby_temp = extruder_train.getSettingInSeconds("material_standby_temperature"); // 150
+    void setConfig(const MeshGroup& meshgroup);
 
-            config.min_time_window = extruder_train.getSettingInSeconds("machine_min_cool_heat_time_window");
-
-            config.material_print_temperature = extruder_train.getSettingInDegreeCelsius("material_print_temperature"); // 220
-            
-            config.flow_dependent_temperature = extruder_train.getSettingBoolean("material_flow_dependent_temperature"); 
-            
-            config.flow_temp_graph = extruder_train.getSettingAsFlowTempGraph("material_flow_temp_graph"); // [[0.1,180],[20,230]]
-        }
-    }
-    
     bool usesFlowDependentTemp(int extruder_nr)
     {
         return config_per_extruder[extruder_nr].flow_dependent_temperature;
     }
-private:
     /*!
-     * Calculate time to heat up from standby temperature to a given temperature.
-     * Assumes @p temp is higher than the standby temperature.
+     * Get the optimal temperature corresponding to a given average flow,
+     * or the initial layer temperature.
      * 
-     * \param extruder The extruder for which to get the time
-     * \param temp The temperature to be reached
-     */
-    double timeToHeatFromStandbyToPrintTemp(unsigned int extruder, double temp)
-    {
-        return (temp - config_per_extruder[extruder].standby_temp) * config_per_extruder[extruder].time_to_heatup_1_degree; 
-    }
-
-public:
-    
-    /*!
-     * Get the optimal temperature corresponding to a given average flow.
      * \param extruder The extruder train
      * \param flow The flow for which to get the optimal temperature
+     * \param is_initial_layer Whether the initial layer temperature should be returned instead of flow-based temperature
      * \return The corresponding optimal temperature
      */
-    double getTemp(unsigned int extruder, double flow)
-    {
-        return config_per_extruder[extruder].flow_temp_graph.getTemp(flow, config_per_extruder[extruder].material_print_temperature, config_per_extruder[extruder].flow_dependent_temperature);
-    }
+    double getTemp(unsigned int extruder, double flow, bool is_initial_layer);
 
     /*!
      * Return the minimal time window of a specific extruder for letting an unused extruder cool down and warm up again
@@ -142,76 +139,62 @@ public:
     }
 
     /*!
-     * Decide when to start warming up again after starting to cool down towards the standby temperature.
+     * Decide when to start warming up again after starting to cool down towards \p temp_mid.
      * Two cases are considered: 
      * the case where the standby temperature is reached  \__/    .
      * and the case where it isn't  \/    .
      * 
-     * IT is assumed that the printer is not printing during this cool down and warm up time.
-     * 
-     * Assumes from_temp is approximately the same as @p temp
+     * \warning it is assumed that \p temp_mid is lower than both \p temp_start and \p temp_end. If not somewhat weird results may follow.
      * 
+    //                    ,temp_end
+    //                   /                                    .
+    //     ,temp_start  /                                     .
+    //      \          /                                      .
+    //       \________/                                       .
+    //               "-> temp_mid
      * \param window_time The time window within which the cooldown and heat up must take place.
      * \param extruder The extruder used
-     * \param temp The temperature to which to heat
+     * \param temp_start The temperature from which to start cooling down
+     * \param temp_mid The temeprature to which we try to cool down
+     * \param temp_end The temperature to which we need to have heated up at the end of the \p time_window
+     * \param during_printing Whether the warming up and cooling down is performed during printing
      * \return The time before the end of the @p time_window to insert the preheat command and the temperature from which the heating starts
      */
-    WarmUpResult timeBeforeEndToInsertPreheatCommand_coolDownWarmUp(double time_window, unsigned int extruder, double temp)
-    {
-        WarmUpResult result;
-        const Config& config = config_per_extruder[extruder];
-        result.total_time_window = time_window;
-        double time_ratio_cooldown_heatup = config.time_to_cooldown_1_degree / config.time_to_heatup_1_degree;
-        double time_to_heat_from_standby_to_print_temp = timeToHeatFromStandbyToPrintTemp(extruder, temp);
-        double time_needed_to_reach_standby_temp = time_to_heat_from_standby_to_print_temp * (1.0 + time_ratio_cooldown_heatup);
-        if (time_needed_to_reach_standby_temp < time_window)
-        {
-            result.heating_time = time_to_heat_from_standby_to_print_temp;
-            result.lowest_temperature = config.standby_temp;
-        }
-        else 
-        {
-            result.heating_time = time_window * config.time_to_heatup_1_degree / (config.time_to_cooldown_1_degree + config.time_to_heatup_1_degree);
-            result.lowest_temperature = std::max(config.standby_temp, temp - result.heating_time / config.time_to_heatup_1_degree);
-        }
-        return result;
-    }
+    WarmUpResult getWarmUpPointAfterCoolDown(double time_window, unsigned int extruder, double temp_start, double temp_mid, double temp_end, bool during_printing);
+
     /*!
-     * Calculate time needed to warm up the nozzle from a given temp to a given temp.
-     * If the printer is printing in the mean time the warming up will take longer.
+     * Decide when to start cooling down again after starting to warm up towards the \p temp_mid
+     * Two cases are considered: 
+     * the case where the temperature is reached  /"""\    .
+     * and the case where it isn't  /\    .
      * 
+     * \warning it is assumed that \p temp_mid is higher than both \p temp_start and \p temp_end. If not somewhat weird results may follow.
      * 
-     * \param from_temp The temperature at which the nozzle was before
+    //               _> temp_mid
+    //       /""""""""\                                       .
+    //      /          \                                      .
+    //     ^temp_start  \                                     .
+    //                   \                                    .
+    //                    ^temp_end
+     * \param window_time The time window within which the cooldown and heat up must take place.
      * \param extruder The extruder used
-     * \param temp The temperature to which to heat
-     * \param printing Whether the printer is printing in the time to heat up the nozzle
-     * \return The time needed to reach the desired temperature (@p temp)
+     * \param temp_start The temperature from which to start heating up
+     * \param temp_mid The temeprature to which we try to heat up
+     * \param temp_end The temperature to which we need to have cooled down after \p time_window time
+     * \param during_printing Whether the warming up and cooling down is performed during printing
+     * \return The time before the end of the \p time_window to insert the preheat command and the temperature from which the cooling starts
      */
-    double timeBeforeEndToInsertPreheatCommand_warmUp(double from_temp, unsigned int extruder, double temp, bool printing)
-    {
-        if (temp > from_temp)
-        {
-            if (printing)
-            {
-                return (temp - from_temp) * (config_per_extruder[extruder].time_to_heatup_1_degree + config_per_extruder[extruder].heatup_cooldown_time_mod_while_printing); 
-            }
-            else 
-            {
-                return (temp - from_temp) * config_per_extruder[extruder].time_to_heatup_1_degree; 
-            }
-        }
-        else 
-        {
-            if (printing)
-            {
-                return (from_temp - temp) * config_per_extruder[extruder].time_to_cooldown_1_degree; 
-            }
-            else 
-            {
-                return (from_temp - temp) * std::max(0.0, config_per_extruder[extruder].time_to_cooldown_1_degree - config_per_extruder[extruder].heatup_cooldown_time_mod_while_printing); 
-            }
-        }
-    }
+    CoolDownResult getCoolDownPointAfterWarmUp(double time_window, unsigned int extruder, double temp_start, double temp_mid, double temp_end, bool during_printing);
+
+    /*!
+     * Get the time to go from one temperature to another temperature
+     * \param extruder The extruder number for which to perform the heatup / cooldown
+     * \param temp_before The before temperature
+     * \param temp_after The after temperature
+     * \param during_printing Whether the planned cooldown / warmup occurs during printing or while in standby mode
+     * \return The time needed
+     */
+    double getTimeToGoFromTempToTemp(int extruder, double temp_before, double temp_after, bool during_printing);
 };
 
 } // namespace cura 

src/PrimeTower.cpp

@@ -12,13 +12,22 @@
 namespace cura 
 {
 
-PrimeTower::PrimeTower()
-: current_pre_wipe_location_idx(0)
+PrimeTower::PrimeTower(const SliceDataStorage& storage)
+: is_hollow(false)
+, wipe_from_middle(false)
+, current_pre_wipe_location_idx(0)
 {
     for (int extruder_nr = 0; extruder_nr < MAX_EXTRUDERS; extruder_nr++)
     {
         last_prime_tower_poly_printed[extruder_nr] = -1;
     }
+    enabled = storage.getSettingBoolean("prime_tower_enable")
+           && storage.getSettingInMicrons("prime_tower_wall_thickness") > 10
+           && storage.getSettingInMicrons("prime_tower_size") > 10;
+    if (enabled)
+    {
+        generateGroundpoly(storage);
+    }
 }
 
 
@@ -40,7 +49,6 @@ void PrimeTower::initConfigs(const MeshGroup* meshgroup)
 
 void PrimeTower::setConfigs(const MeshGroup* meshgroup, const int layer_thickness)
 {
-
     extruder_count = meshgroup->getExtruderCount();
 
     for (int extr = 0; extr < extruder_count; extr++)
@@ -50,65 +58,19 @@ void PrimeTower::setConfigs(const MeshGroup* meshgroup, const int layer_thicknes
     }
 }
 
-    
-
-void PrimeTower::computePrimeTowerMax(SliceDataStorage& storage)
-{ // compute storage.max_object_height_second_to_last_extruder, which is used to determine the highest point in the prime tower
-        
-    extruder_count = storage.meshgroup->getExtruderCount();
-    
-    int max_object_height_per_extruder[extruder_count]; 
-    std::fill_n(max_object_height_per_extruder, extruder_count, -1); // unitialize all as -1
-    { // compute max_object_height_per_extruder
-        for (SliceMeshStorage& mesh : storage.meshes)
-        {
-            unsigned int extr_nr = mesh.getSettingAsIndex("extruder_nr");
-            max_object_height_per_extruder[extr_nr] = 
-                std::max(   max_object_height_per_extruder[extr_nr]
-                        ,   mesh.layer_nr_max_filled_layer  ); 
-        }
-        int support_infill_extruder_nr = storage.getSettingAsIndex("support_infill_extruder_nr"); // TODO: support extruder should be configurable per object
-        max_object_height_per_extruder[support_infill_extruder_nr] = 
-        std::max(   max_object_height_per_extruder[support_infill_extruder_nr]
-                ,   storage.support.layer_nr_max_filled_layer  ); 
-        int support_skin_extruder_nr = storage.getSettingAsIndex("support_interface_extruder_nr"); // TODO: support skin extruder should be configurable per object
-        max_object_height_per_extruder[support_skin_extruder_nr] = 
-        std::max(   max_object_height_per_extruder[support_skin_extruder_nr]
-                ,   storage.support.layer_nr_max_filled_layer  ); 
-    }
-    { // // compute max_object_height_second_to_last_extruder
-        int extruder_max_object_height = 0;
-        for (int extruder_nr = 1; extruder_nr < extruder_count; extruder_nr++)
-        {
-            if (max_object_height_per_extruder[extruder_nr] > max_object_height_per_extruder[extruder_max_object_height])
-            {
-                extruder_max_object_height = extruder_nr;
-            }
-        }
-        int extruder_second_max_object_height = -1;
-        for (int extruder_nr = 0; extruder_nr < extruder_count; extruder_nr++)
-        {
-            if (extruder_nr == extruder_max_object_height) { continue; }
-            if (extruder_second_max_object_height == -1 || max_object_height_per_extruder[extruder_nr] > max_object_height_per_extruder[extruder_second_max_object_height])
-            {
-                extruder_second_max_object_height = extruder_nr;
-            }
-        }
-        if (extruder_second_max_object_height < 0)
-        {
-            storage.max_object_height_second_to_last_extruder = -1;
-        }
-        else
-        {
-            storage.max_object_height_second_to_last_extruder = max_object_height_per_extruder[extruder_second_max_object_height];
-        }
-    }
-}
-
 void PrimeTower::generateGroundpoly(const SliceDataStorage& storage)
 {
+    extruder_count = storage.meshgroup->getExtruderCount();
+
+    int64_t prime_tower_wall_thickness = storage.getSettingInMicrons("prime_tower_wall_thickness");
+    int64_t tower_size = storage.getSettingInMicrons("prime_tower_size");
+
+    if (prime_tower_wall_thickness * 2 < tower_size)
+    {
+        is_hollow = true;
+    }
+
     PolygonRef p = ground_poly.newPoly();
-    int tower_size = storage.getSettingInMicrons("prime_tower_size");
     int tower_distance = 0; 
     int x = storage.getSettingInMicrons("prime_tower_position_x"); // storage.model_max.x
     int y = storage.getSettingInMicrons("prime_tower_position_y"); // storage.model_max.y
@@ -116,13 +78,20 @@ void PrimeTower::generateGroundpoly(const SliceDataStorage& storage)
     p.add(Point(x + tower_distance, y + tower_distance + tower_size));
     p.add(Point(x + tower_distance - tower_size, y + tower_distance + tower_size));
     p.add(Point(x + tower_distance - tower_size, y + tower_distance));
+    middle = Point(x - tower_size / 2, y + tower_size / 2);
+
+    if (is_hollow)
+    {
+        ground_poly = ground_poly.difference(ground_poly.offset(-prime_tower_wall_thickness));
+    }
 
     post_wipe_point = Point(x + tower_distance - tower_size / 2, y + tower_distance + tower_size / 2);
 }
 
-void PrimeTower::generatePaths(const SliceDataStorage& storage, unsigned int total_layers)
+void PrimeTower::generatePaths(const SliceDataStorage& storage)
 {
-    if (storage.max_object_height_second_to_last_extruder >= 0 && storage.getSettingBoolean("prime_tower_enable"))
+    enabled &= storage.max_print_height_second_to_last_extruder >= 0; //Maybe it turns out that we don't need a prime tower after all because there are no layer switches.
+    if (enabled)
     {
         generatePaths_denseInfill(storage);
         generateWipeLocations(storage);
@@ -135,22 +104,22 @@ void PrimeTower::generatePaths_denseInfill(const SliceDataStorage& storage)
     int infill_overlap = 60; // so that it can't be zero; EDIT: wtf?
     int extra_infill_shift = 0;
 
-    generateGroundpoly(storage);
-
     int64_t z = 0; // (TODO) because the prime tower stores the paths for each extruder for once instead of generating each layer, we don't know the z position
 
     for (int extruder = 0; extruder < extruder_count; extruder++)
     {
         int line_width = storage.meshgroup->getExtruderTrain(extruder)->getSettingInMicrons("prime_tower_line_width");
         patterns_per_extruder.emplace_back(n_patterns);
-        std::vector<Polygons>& patterns = patterns_per_extruder.back();
+        std::vector<ExtrusionMoves>& patterns = patterns_per_extruder.back();
+        patterns.resize(n_patterns);
         for (int pattern_idx = 0; pattern_idx < n_patterns; pattern_idx++)
         {
-            Polygons result_polygons; // should remain empty, since we generate lines pattern!
+            patterns[pattern_idx].polygons = ground_poly.offset(-line_width / 2);
+            Polygons& result_lines = patterns[pattern_idx].lines;
             int outline_offset = -line_width;
             int line_distance = line_width;
             double fill_angle = 45 + pattern_idx * 90;
-            Polygons& result_lines = patterns[pattern_idx];
+            Polygons result_polygons; // should remain empty, since we generate lines pattern!
             Infill infill_comp(EFillMethod::LINES, ground_poly, outline_offset, line_width, line_distance, infill_overlap, fill_angle, z, extra_infill_shift);
             infill_comp.generate(result_polygons, result_lines);
         }
@@ -158,9 +127,9 @@ void PrimeTower::generatePaths_denseInfill(const SliceDataStorage& storage)
 }
 
 
-void PrimeTower::addToGcode(const SliceDataStorage& storage, GCodePlanner& gcodeLayer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder, bool wipe)
+void PrimeTower::addToGcode(const SliceDataStorage& storage, GCodePlanner& gcodeLayer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder, const int new_extruder)
 {
-    if (!( storage.max_object_height_second_to_last_extruder >= 0 && storage.getSettingInMicrons("prime_tower_size") > 0) )
+    if (!enabled)
     {
         return;
     }
@@ -174,48 +143,44 @@ void PrimeTower::addToGcode(const SliceDataStorage& storage, GCodePlanner& gcode
         return;
     }
 
-    if (layer_nr > storage.max_object_height_second_to_last_extruder + 1)
+    if (layer_nr > storage.max_print_height_second_to_last_extruder + 1)
     {
         return;
     }
 
-    int new_extruder = gcodeLayer.getExtruder();
-    if (prev_extruder == gcodeLayer.getExtruder())
+    bool pre_wipe = storage.meshgroup->getExtruderTrain(new_extruder)->getSettingBoolean("dual_pre_wipe");
+    bool post_wipe = storage.meshgroup->getExtruderTrain(prev_extruder)->getSettingBoolean("prime_tower_wipe_enabled");
+
+    if (prev_extruder == new_extruder)
     {
-        wipe = false;
+        pre_wipe = false;
+        post_wipe = false;
     }
     // pre-wipe:
-    if (wipe)
+    if (pre_wipe)
     {
         preWipe(storage, gcodeLayer, new_extruder);
     }
 
-    addToGcode_denseInfill(storage, gcodeLayer, gcode, layer_nr, prev_extruder);
+    addToGcode_denseInfill(gcodeLayer, layer_nr, new_extruder);
 
     // post-wipe:
-    if (false && wipe) // TODO: make a separate setting for the post-wipe!
+    if (post_wipe)
     { //Make sure we wipe the old extruder on the prime tower.
         gcodeLayer.addTravel(post_wipe_point - gcode.getExtruderOffset(prev_extruder) + gcode.getExtruderOffset(new_extruder));
     }
 }
 
-void PrimeTower::addToGcode_denseInfill(const SliceDataStorage& storage, GCodePlanner& gcodeLayer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder)
+void PrimeTower::addToGcode_denseInfill(GCodePlanner& gcodeLayer, const int layer_nr, const int extruder)
 {
-    int new_extruder = gcodeLayer.getExtruder();
+    ExtrusionMoves& pattern = patterns_per_extruder[extruder][((layer_nr % 2) + 2) % 2]; // +2) %2 to handle negative layer numbers
 
-    Polygons& pattern = patterns_per_extruder[new_extruder][layer_nr % 2];
+    GCodePathConfig& config = config_per_extruder[extruder];
 
+    gcodeLayer.addPolygonsByOptimizer(pattern.polygons, &config);
+    gcodeLayer.addLinesByOptimizer(pattern.lines, &config, SpaceFillType::Lines);
 
-    GCodePathConfig& config = config_per_extruder[new_extruder];
-    int start_idx = 0; // TODO: figure out which idx is closest to the far right corner
-
-    Polygon outer_wall = ground_poly.offset(-config.getLineWidth() / 2).back();
-    gcodeLayer.addPolygon(outer_wall, start_idx, &config);
-    gcodeLayer.addLinesByOptimizer(pattern, &config, SpaceFillType::Lines);
-
-    last_prime_tower_poly_printed[new_extruder] = layer_nr;
-
-    CommandSocket::sendPolygons(PrintFeatureType::Support, pattern, config.getLineWidth());
+    last_prime_tower_poly_printed[extruder] = layer_nr;
 }
 
 Point PrimeTower::getLocationBeforePrimeTower(const SliceDataStorage& storage)
@@ -248,37 +213,52 @@ Point PrimeTower::getLocationBeforePrimeTower(const SliceDataStorage& storage)
 
 void PrimeTower::generateWipeLocations(const SliceDataStorage& storage)
 {
-    Point from = getLocationBeforePrimeTower(storage);
-
-    // take the closer corner of the wipe tower and generate wipe locations on that side only:
-    //
-    //     |
-    //     |
-    //     +-----
-    //  .
-    //  ^ nozzle switch location
+    wipe_from_middle = is_hollow;
+    // only wipe from the middle of the prime tower if we have a z hop already on the first move after the layer switch
+    for (int extruder_nr = 0; extruder_nr < storage.meshgroup->getExtruderCount(); extruder_nr++)
+    {
+        const ExtruderTrain& train = *storage.meshgroup->getExtruderTrain(extruder_nr);
+        wipe_from_middle &= train.getSettingBoolean("retraction_hop_enabled") 
+                        && (!train.getSettingBoolean("retraction_hop_only_when_collides") || train.getSettingBoolean("retraction_hop_after_extruder_switch"));
+    }
 
     PolygonsPointIndex segment_start; // from where to start the sequence of wipe points
     PolygonsPointIndex segment_end; // where to end the sequence of wipe points
 
-    // find the single line segment closest to [from] pointing most toward [from]
-    PolygonsPointIndex closest_vert = PolygonUtils::findNearestVert(from, ground_poly);
-    PolygonsPointIndex prev = closest_vert.prev();
-    PolygonsPointIndex next = closest_vert.next();
-    int64_t prev_dot_score = dot(from - closest_vert.p(), turn90CCW(prev.p() - closest_vert.p()));
-    int64_t next_dot_score = dot(from - closest_vert.p(), turn90CCW(closest_vert.p() - next.p()));
-    if (prev_dot_score > next_dot_score)
+    if (wipe_from_middle)
     {
-        segment_start = prev;
-        segment_end = closest_vert;
+        // take the same start as end point so that the whole poly os covered.
+        // find the inner polygon.
+        segment_start = segment_end = PolygonUtils::findNearestVert(middle, ground_poly);
     }
     else
     {
-        segment_start = closest_vert;
-        segment_end = next;
-    }
+        // take the closer corner of the wipe tower and generate wipe locations on that side only:
+        //
+        //     |
+        //     |
+        //     +-----
+        //  .
+        //  ^ nozzle switch location
+        Point from = getLocationBeforePrimeTower(storage);
 
-    // TODO: come up with alternatives for better segments once the prime tower can be different shapes
+        // find the single line segment closest to [from] pointing most toward [from]
+        PolygonsPointIndex closest_vert = PolygonUtils::findNearestVert(from, ground_poly);
+        PolygonsPointIndex prev = closest_vert.prev();
+        PolygonsPointIndex next = closest_vert.next();
+        int64_t prev_dot_score = dot(from - closest_vert.p(), turn90CCW(prev.p() - closest_vert.p()));
+        int64_t next_dot_score = dot(from - closest_vert.p(), turn90CCW(closest_vert.p() - next.p()));
+        if (prev_dot_score > next_dot_score)
+        {
+            segment_start = prev;
+            segment_end = closest_vert;
+        }
+        else
+        {
+            segment_start = closest_vert;
+            segment_end = next;
+        }
+    }
 
     PolygonUtils::spreadDots(segment_start, segment_end, number_of_pre_wipe_locations, pre_wipe_locations);
 }
@@ -294,16 +274,37 @@ void PrimeTower::preWipe(const SliceDataStorage& storage, GCodePlanner& gcode_la
     const Point end = PolygonUtils::moveInsideDiagonally(wipe_location, inward_dist);
     const Point outward_dir = wipe_location.location - end;
     const Point start = wipe_location.location + normal(outward_dir, start_dist);
-    // for hollow wipe tower:
-    // start from above
-    // go to the level of the previous layer
-    // wipe
-    // go to normal layer height (automatically on the next extrusion move...
-    gcode_layer.addTravel(start); // TODO: verify that this move has a z hop ==> cylindric wipe tower
-//     gcode_layer.makeLastPathZhopped which calls forceNewPathStart TODO ==> cylindric wipe tower
+    if (wipe_from_middle)
+    {
+        // for hollow wipe tower:
+        // start from above
+        // go to wipe start
+        // go to the Z height of the previous/current layer
+        // wipe
+        // go to normal layer height (automatically on the next extrusion move)...
+        GCodePath& toward_middle = gcode_layer.addTravel(middle);
+        toward_middle.perform_z_hop = true;
+        gcode_layer.forceNewPathStart();
+        GCodePath& toward_wipe_start = gcode_layer.addTravel_simple(start);
+        toward_wipe_start.perform_z_hop = false;
+        toward_wipe_start.retract = true;
+    }
+    else
+    {
+        gcode_layer.addTravel(start);
+    }
     float flow = 0.0001; // force this path being interpreted as an extrusion path, so that no Z hop will occur (TODO: really separately handle travel and extrusion moves)
     gcode_layer.addExtrusionMove(end, &config_per_extruder[extruder_nr], SpaceFillType::None, flow);
 }
 
+void PrimeTower::subtractFromSupport(SliceDataStorage& storage)
+{
+    const Polygons outside_polygon = ground_poly.getOutsidePolygons();
+    for(size_t layer = 0; layer <= (size_t)storage.max_print_height_second_to_last_extruder + 1 && layer < storage.support.supportLayers.size(); layer++)
+    {
+        storage.support.supportLayers[layer].supportAreas = storage.support.supportLayers[layer].supportAreas.difference(outside_polygon);
+    }
+}
+
 
 }//namespace cura

src/PrimeTower.h

@@ -1,3 +1,6 @@
+//Copyright (c) 2016 Ultimaker B.V.
+//CuraEngine is released under the terms of the AGPLv3 or higher.
+
 #ifndef PRIME_TOWER_H
 #define PRIME_TOWER_H
 
@@ -16,8 +19,6 @@ class SliceDataStorage;
 class GCodePlanner;
 class GCodeExport;
 
-typedef std::vector<IntPoint> PolyLine;
-
 /*!
  * Class for everything to do with the prime tower:
  * - generating the areas
@@ -27,22 +28,41 @@ typedef std::vector<IntPoint> PolyLine;
 class PrimeTower
 {
 private:
+    struct ExtrusionMoves
+    {
+        Polygons polygons;
+        Polygons lines;
+    };
     int extruder_count; //!< number of extruders
     std::vector<GCodePathConfig> config_per_extruder; //!< Path config for prime tower for each extruder
 
+    bool is_hollow; //!< Whether the prime tower is hollow
+
+    bool wipe_from_middle; //!< Whether to wipe on the inside of the hollow prime tower
+    Point middle; //!< The middle of the prime tower
+
     Point post_wipe_point; //!< location to post-wipe the unused nozzle off on
 
-    std::vector<PolyLine> extruder_paths; //!< Precomputed so that we don't need to generate the paths each layer over again
-
     std::vector<ClosestPolygonPoint> pre_wipe_locations; //!< The differernt locations where to pre-wipe the active nozzle
-    const unsigned int pre_wipe_location_skip = 8; //!< How big the steps are when stepping through \ref PrimeTower::wipe_locations
-    const unsigned int number_of_pre_wipe_locations = 13; //!< The required size of \ref PrimeTower::wipe_locations
-    // note that the above are two consecutive numbers in the fibonacci sequence
+    const unsigned int pre_wipe_location_skip = 13; //!< How big the steps are when stepping through \ref PrimeTower::wipe_locations
+    const unsigned int number_of_pre_wipe_locations = 21; //!< The required size of \ref PrimeTower::wipe_locations
+    // note that the above are two consecutive numbers in the Fibonacci sequence
     int current_pre_wipe_location_idx; //!< Index into \ref PrimeTower::wipe_locations of where to pre-wipe the nozzle
 
 public:
+    bool enabled; //!< Whether the prime tower is enabled.
     Polygons ground_poly; //!< The outline of the prime tower to be used for each layer
 
+    std::vector<std::vector<ExtrusionMoves>> patterns_per_extruder; //!< for each extruder a vector of patterns to alternate between, over the layers
+
+    /*!
+     * \brief Creates a prime tower instance that will determine where and how
+     * the prime tower gets printed.
+     *
+     * \param storage A storage where it retrieves the prime tower settings.
+     */
+    PrimeTower(const SliceDataStorage& storage);
+
     /*!
      * Initialize \ref PrimeTower::config_per_extruder with speed and line width settings.
      * 
@@ -61,28 +81,19 @@ public:
     /*!
      * Generate the prime tower area to be used on each layer
      * 
+     * Fills \ref PrimeTower::ground_poly and sets \ref PrimeTower::middle
+     * 
      * \param storage Where to retrieve prime tower settings from
      */
     void generateGroundpoly(const SliceDataStorage& storage);
 
-    std::vector<std::vector<Polygons>> patterns_per_extruder; //!< for each extruder a vector of patterns to alternate between, over the layers
-
     /*!
      * Generate the area where the prime tower should be.
      * 
      * \param storage where to get settings from
      * \param total_layers The total number of layers 
      */
-    void generatePaths(const SliceDataStorage& storage, unsigned int total_layers);
-
-    /*!
-     * Compute the maximum layer at which a layer switch will occur and store the result in \ref SliceDataStorage::max_object_height_second_to_last_extruder
-     * 
-     * \param[in,out] storage Where to retrieve area data and extruder settings for those areas; where to store the max_object_height_second_to_last_extruder
-     */
-    void computePrimeTowerMax(SliceDataStorage& storage);
-
-    PrimeTower(); //!< basic constructor
+    void generatePaths(const SliceDataStorage& storage);
 
     /*!
      * Add path plans for the prime tower to the \p gcode_layer
@@ -91,9 +102,18 @@ public:
      * \param[in,out] gcode_layer Where to get the current extruder from; where to store the generated layer paths
      * \param layer_nr The layer for which to generate the prime tower paths
      * \param prev_extruder The previous extruder with which paths were planned; from which extruder a switch was made
-     * \param wipe Whether to wipe of the (not previous, but) current nozzle on the wipe tower (only occurs if previous extruder is different fromt he current one)
+     * \param new_extruder The switched to extruder with which the prime tower paths should be generated.
      */
-    void addToGcode(const SliceDataStorage& storage, GCodePlanner& gcode_layer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder, bool wipe);
+    void addToGcode(const SliceDataStorage& storage, GCodePlanner& gcode_layer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder, const int new_extruder);
+
+    /*!
+     * \brief Subtract the prime tower from the support areas in storage.
+     *
+     * \param storage The storage where to find the support from which to
+     * subtract a prime tower.
+     */
+    void subtractFromSupport(SliceDataStorage& storage);
+
 private:
     /*!
      * Layer number of the last layer in which a prime tower has been printed per extruder train.  
@@ -121,7 +141,8 @@ private:
     /*!
      * \see WipeTower::generatePaths
      * 
-     * Generate the area where the prime tower should be.
+     * Generate the extrude paths for each extruder on even and odd layers
+     * Fill the ground poly with dense infill.
      * 
      * \param storage where to get settings from
      * \param total_layers The total number of layers 
@@ -130,15 +151,15 @@ private:
 
     /*!
      * \see PrimeTower::addToGcode
-     * 
+     *
      * Add path plans for the prime tower to the \p gcode_layer
-     * 
-     * \param storage where to get settings from; where to get the maximum height of the prime tower from
+     *
      * \param[in,out] gcode_layer Where to get the current extruder from; where to store the generated layer paths
      * \param layer_nr The layer for which to generate the prime tower paths
-     * \param prev_extruder The previous extruder with which paths were planned; from which extruder a switch was made
+     * \param extruder The extruder we just switched to, with which the prime
+     * tower paths should be drawn.
      */
-    void addToGcode_denseInfill(const SliceDataStorage& storage, GCodePlanner& gcode_layer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder);
+    void addToGcode_denseInfill(GCodePlanner& gcode_layer, const int layer_nr, const int extruder);
 
     /*!
      * Plan the moves for wiping the current nozzles oozed material before starting to print the prime tower.

src/SkirtBrim.cpp

@@ -1,4 +1,7 @@
-/** Copyright (C) 2013 David Braam - Released under terms of the AGPLv3 License */
+//Copyright (C) 2013 David Braam
+//Copyright (c) 2016 Ultimaker B.V.
+//CuraEngine is released under the terms of the AGPLv3 or higher.
+
 #include "SkirtBrim.h"
 #include "support.h"
 
@@ -19,7 +22,7 @@ void SkirtBrim::getFirstLayerOutline(SliceDataStorage& storage, const unsigned i
     { // add brim underneath support by removing support where there's brim around the model
         const bool include_helper_parts = false; // include manually below
         first_layer_outline = storage.getLayerOutlines(layer_nr, include_helper_parts, external_only);
-        first_layer_outline.add(storage.primeTower.ground_poly); // don't remove parts of the prime tower, but make a brim for it
+        first_layer_outline = first_layer_outline.unionPolygons(); //To guard against overlapping outlines, which would produce holes according to the even-odd rule.
         Polygons first_layer_empty_holes;
         if (outside_only)
         {
@@ -35,7 +38,7 @@ void SkirtBrim::getFirstLayerOutline(SliceDataStorage& storage, const unsigned i
             //  || ||     ||[]|| > expand to fit an extra brim line
             //  |+-+|     |+--+|
             //  +---+     +----+ 
-            Polygons model_brim_covered_area = first_layer_outline.offset(primary_extruder_skirt_brim_line_width * (primary_line_count + primary_line_count % 2)); // always leave a gap of an even number of brim lines, so that it fits if it's generating brim from both sides
+            Polygons model_brim_covered_area = first_layer_outline.offset(primary_extruder_skirt_brim_line_width * (primary_line_count + primary_line_count % 2), ClipperLib::jtRound); // always leave a gap of an even number of brim lines, so that it fits if it's generating brim from both sides
             if (outside_only)
             { // don't remove support within empty holes where no brim is generated.
                 model_brim_covered_area.add(first_layer_empty_holes);
@@ -45,6 +48,10 @@ void SkirtBrim::getFirstLayerOutline(SliceDataStorage& storage, const unsigned i
             first_layer_outline.add(support_layer.supportAreas);
             first_layer_outline.add(support_layer.skin);
         }
+        if (storage.primeTower.enabled)
+        {
+            first_layer_outline.add(storage.primeTower.ground_poly); // don't remove parts of the prime tower, but make a brim for it
+        }
     }
     constexpr int join_distance = 20;
     first_layer_outline = first_layer_outline.offset(join_distance).offset(-join_distance); // merge adjacent models into single polygon

src/Wireframe2gcode.cpp

@@ -18,8 +18,9 @@ void Wireframe2gcode::writeGCode()
 {
 
     gcode.preSetup(wireFrame.meshgroup);
-    
-    gcode.setInitialTemps(*wireFrame.meshgroup);
+
+    const unsigned int start_extruder_nr = getSettingAsIndex("adhesion_extruder_nr"); // TODO: figure out how Wireframe works with dual extrusion
+    gcode.setInitialTemps(*wireFrame.meshgroup, start_extruder_nr);
     
     if (CommandSocket::getInstance())
         CommandSocket::getInstance()->beginGCode();
@@ -159,7 +160,7 @@ void Wireframe2gcode::writeGCode()
     
     gcode.setZ(maxObjectHeight);
     
-    gcode.writeRetraction(&standard_retraction_config);
+    gcode.writeRetraction(standard_retraction_config);
     
     
     gcode.updateTotalPrintTime();
@@ -259,7 +260,7 @@ void Wireframe2gcode::strategy_retract(WeaveLayer& layer, WeaveConnectionPart& p
         Point3 lowering = vec * retract_hop_dist / 2 / vec.vSize();
         Point3 lower = to - lowering;
         gcode.writeMove(lower, speedUp, extrusion_mm3_per_mm_connection);
-        gcode.writeRetraction(&retraction_config);
+        gcode.writeRetraction(retraction_config);
         gcode.writeMove(to + lowering, speedUp, 0);
         gcode.writeDelay(top_retract_pause);
         if (after_retract_hop)
@@ -268,7 +269,7 @@ void Wireframe2gcode::strategy_retract(WeaveLayer& layer, WeaveConnectionPart& p
     } else 
     {
         gcode.writeMove(to, speedUp, extrusion_mm3_per_mm_connection);
-        gcode.writeRetraction(&retraction_config);
+        gcode.writeRetraction(retraction_config);
         gcode.writeMove(to + Point3(0, 0, retract_hop_dist), speedFlat, 0);
         gcode.writeDelay(top_retract_pause);
         if (after_retract_hop)    
@@ -467,14 +468,14 @@ void Wireframe2gcode::writeFill(std::vector<WeaveRoofPart>& infill_insets, Polyg
 void Wireframe2gcode::writeMoveWithRetract(Point3 to)
 {
     if ((gcode.getPosition() - to).vSize2() >= nozzle_top_diameter * nozzle_top_diameter * 2 * 2)
-        gcode.writeRetraction(&standard_retraction_config);
+        gcode.writeRetraction(standard_retraction_config);
     gcode.writeMove(to, moveSpeed, 0);
 }
 
 void Wireframe2gcode::writeMoveWithRetract(Point to)
 {
     if (vSize2(gcode.getPositionXY() - to) >= nozzle_top_diameter * nozzle_top_diameter * 2 * 2)
-        gcode.writeRetraction(&standard_retraction_config);
+        gcode.writeRetraction(standard_retraction_config);
     gcode.writeMove(to, moveSpeed, 0);
 }
 
@@ -562,7 +563,7 @@ void Wireframe2gcode::processStartingCode()
     {
         if (getSettingBoolean("material_bed_temp_prepend"))
         {
-            if (getSettingBoolean("machine_heated_bed") && getSettingInDegreeCelsius("material_bed_temperature") > 0)
+            if (getSettingBoolean("machine_heated_bed") && getSettingInDegreeCelsius("material_bed_temperature") != 0)
             {
                 gcode.writeBedTemperatureCommand(getSettingInDegreeCelsius("material_bed_temperature"), getSettingBoolean("material_bed_temp_wait"));
             }
@@ -603,7 +604,7 @@ void Wireframe2gcode::processStartingCode()
         constexpr bool wait = true;
         gcode.writeTemperatureCommand(start_extruder_nr, getSettingInDegreeCelsius("material_print_temperature"), wait);
         gcode.writePrimeTrain(getSettingInMillimetersPerSecond("speed_travel"));
-        gcode.writeRetraction(&standard_retraction_config);
+        gcode.writeRetraction(standard_retraction_config);
     }
 }
 

src/gcodeExport.cpp

@@ -11,6 +11,8 @@
 
 namespace cura {
 
+double layer_height; //!< report basic layer height in RepRap gcode file.
+
 GCodeExport::GCodeExport()
 : output_stream(&std::cout)
 , currentPosition(0,0,MM2INT(20))
@@ -34,6 +36,8 @@ GCodeExport::GCodeExport()
     initial_bed_temp = 0;
 
     extruder_count = 0;
+
+    total_bounding_box = AABB3D();
 }
 
 GCodeExport::~GCodeExport()
@@ -49,14 +53,19 @@ void GCodeExport::preSetup(const MeshGroup* meshgroup)
 
     for (const Mesh& mesh : meshgroup->meshes)
     {
-        extruder_attr[mesh.getSettingAsIndex("extruder_nr")].is_used = true;
+        if (!mesh.getSettingBoolean("anti_overhang_mesh")
+            && !mesh.getSettingBoolean("support_mesh")
+        )
+        {
+            extruder_attr[mesh.getSettingAsIndex("extruder_nr")].is_used = true;
+        }
     }
 
     for (unsigned int extruder_nr = 0; extruder_nr < extruder_count; extruder_nr++)
     {
         const ExtruderTrain* train = meshgroup->getExtruderTrain(extruder_nr);
 
-        if (meshgroup->getSettingAsIndex("adhesion_extruder_nr") == int(extruder_nr))
+        if (meshgroup->getSettingAsIndex("adhesion_extruder_nr") == int(extruder_nr) && meshgroup->getSettingAsPlatformAdhesion("adhesion_type") != EPlatformAdhesion::NONE)
         {
             extruder_attr[extruder_nr].is_used = true;
         }
@@ -90,6 +99,8 @@ void GCodeExport::preSetup(const MeshGroup* meshgroup)
 
     machine_name = meshgroup->getSettingString("machine_name");
 
+    layer_height = meshgroup->getSettingInMillimeters("layer_height");
+
     if (flavor == EGCodeFlavor::BFB)
     {
         new_line = "\r\n";
@@ -102,17 +113,19 @@ void GCodeExport::preSetup(const MeshGroup* meshgroup)
     estimateCalculator.setFirmwareDefaults(meshgroup);
 }
 
-void GCodeExport::setInitialTemps(const MeshGroup& settings)
+void GCodeExport::setInitialTemps(const MeshGroup& settings, const unsigned int start_extruder_nr)
 {
     for (unsigned int extr_nr = 0; extr_nr < extruder_count; extr_nr++)
     {
-        const ExtruderTrain* extr_train = settings.getExtruderTrain(extr_nr);
-        assert(extr_train);
-        double temp = extr_train->getSettingInDegreeCelsius((extr_nr == 0)? "material_print_temperature" : "material_standby_temperature");
+        const ExtruderTrain& train = *settings.getExtruderTrain(extr_nr);
+        
+        double print_temp_0 = train.getSettingInDegreeCelsius("material_print_temperature_layer_0");
+        double print_temp_here = (print_temp_0 != 0)? print_temp_0 : train.getSettingInDegreeCelsius("material_print_temperature");
+        double temp = (extr_nr == start_extruder_nr)? print_temp_here : train.getSettingInDegreeCelsius("material_standby_temperature");
         setInitialTemp(extr_nr, temp);
     }
 
-    initial_bed_temp = settings.getSettingInDegreeCelsius("material_bed_temperature");
+    initial_bed_temp = settings.getSettingInDegreeCelsius("material_bed_temperature_layer_0");
 }
 
 void GCodeExport::setInitialTemp(int extruder_nr, double temp)
@@ -163,12 +176,12 @@ std::string GCodeExport::getFileHeader(const double* print_time, const std::vect
             prefix << ";PRINT.TIME:" << static_cast<int>(*print_time) << new_line;
         }
 
-        prefix << ";PRINT.SIZE.MIN.X:0" << new_line;
-        prefix << ";PRINT.SIZE.MIN.Y:0" << new_line;
-        prefix << ";PRINT.SIZE.MIN.Z:0" << new_line;
-        prefix << ";PRINT.SIZE.MAX.X:" << INT2MM(machine_dimensions.x) << new_line;
-        prefix << ";PRINT.SIZE.MAX.Y:" << INT2MM(machine_dimensions.y) << new_line;
-        prefix << ";PRINT.SIZE.MAX.Z:" << INT2MM(machine_dimensions.z) << new_line;
+        prefix << ";PRINT.SIZE.MIN.X:" << INT2MM(total_bounding_box.min.x) << new_line;
+        prefix << ";PRINT.SIZE.MIN.Y:" << INT2MM(total_bounding_box.min.y) << new_line;
+        prefix << ";PRINT.SIZE.MIN.Z:" << INT2MM(total_bounding_box.min.z) << new_line;
+        prefix << ";PRINT.SIZE.MAX.X:" << INT2MM(total_bounding_box.max.x) << new_line;
+        prefix << ";PRINT.SIZE.MAX.Y:" << INT2MM(total_bounding_box.max.y) << new_line;
+        prefix << ";PRINT.SIZE.MAX.Z:" << INT2MM(total_bounding_box.max.z) << new_line;
         prefix << ";END_OF_HEADER" << new_line;
         return prefix.str();
     default:
@@ -182,6 +195,11 @@ std::string GCodeExport::getFileHeader(const double* print_time, const std::vect
             prefix << ";NOZZLE_DIAMETER:" << float(INT2MM(getNozzleSize(0))) << new_line;
             // TODO: the second nozzle size isn't always initiated! ";NOZZLE_DIAMETER2:"
         }
+        else if (flavor == EGCodeFlavor::REPRAP)
+        {
+            prefix << ";Filament used: " << ((filament_used.size() >= 1)? filament_used[0] / (1000 * extruder_attr[0].filament_area) : 0) << "m" << new_line;
+            prefix << ";Layer height: " << layer_height << new_line;
+        }
         return prefix.str();
     }
 }
@@ -550,6 +568,7 @@ void GCodeExport::writeMove(int x, int y, int z, double speed, double extrusion_
     double extrusion_per_mm = mm3ToE(extrusion_mm3_per_mm);
 
     Point gcode_pos = getGcodePos(x,y, current_extruder);
+    total_bounding_box.include(Point3(gcode_pos.X, gcode_pos.Y, z));
 
     if (extrusion_mm3_per_mm > 0.000001)
     {
@@ -623,7 +642,7 @@ void GCodeExport::writeMove(int x, int y, int z, double speed, double extrusion_
     estimateCalculator.plan(TimeEstimateCalculator::Position(INT2MM(currentPosition.x), INT2MM(currentPosition.y), INT2MM(currentPosition.z), eToMm(current_e_value)), speed);
 }
 
-void GCodeExport::writeRetraction(RetractionConfig* config, bool force, bool extruder_switch)
+void GCodeExport::writeRetraction(const RetractionConfig& config, bool force, bool extruder_switch)
 {
     ExtruderTrainAttributes& extr_attr = extruder_attr[current_extruder];
 
@@ -640,7 +659,7 @@ void GCodeExport::writeRetraction(RetractionConfig* config, bool force, bool ext
     }
 
     double old_retraction_e_amount = extr_attr.retraction_e_amount_current;
-    double new_retraction_e_amount = mmToE(config->distance);
+    double new_retraction_e_amount = mmToE(config.distance);
     double retraction_diff_e_amount = old_retraction_e_amount - new_retraction_e_amount;
     if (std::abs(retraction_diff_e_amount) < 0.000001)
     {
@@ -650,23 +669,23 @@ void GCodeExport::writeRetraction(RetractionConfig* config, bool force, bool ext
     { // handle retraction limitation
         double current_extruded_volume = getCurrentExtrudedVolume();
         std::deque<double>& extruded_volume_at_previous_n_retractions = extr_attr.extruded_volume_at_previous_n_retractions;
-        while (int(extruded_volume_at_previous_n_retractions.size()) > config->retraction_count_max && !extruded_volume_at_previous_n_retractions.empty()) 
+        while (int(extruded_volume_at_previous_n_retractions.size()) > config.retraction_count_max && !extruded_volume_at_previous_n_retractions.empty()) 
         {
             // extruder switch could have introduced data which falls outside the retraction window
             // also the retraction_count_max could have changed between the last retraction and this
             extruded_volume_at_previous_n_retractions.pop_back();
         }
-        if (!force && config->retraction_count_max <= 0)
+        if (!force && config.retraction_count_max <= 0)
         {
             return;
         }
-        if (!force && int(extruded_volume_at_previous_n_retractions.size()) == config->retraction_count_max
-            && current_extruded_volume < extruded_volume_at_previous_n_retractions.back() + config->retraction_extrusion_window * extr_attr.filament_area) 
+        if (!force && int(extruded_volume_at_previous_n_retractions.size()) == config.retraction_count_max
+            && current_extruded_volume < extruded_volume_at_previous_n_retractions.back() + config.retraction_extrusion_window * extr_attr.filament_area) 
         {
             return;
         }
         extruded_volume_at_previous_n_retractions.push_front(current_extruded_volume);
-        if (int(extruded_volume_at_previous_n_retractions.size()) == config->retraction_count_max + 1) 
+        if (int(extruded_volume_at_previous_n_retractions.size()) == config.retraction_count_max + 1) 
         {
             extruded_volume_at_previous_n_retractions.pop_back();
         }
@@ -689,17 +708,17 @@ void GCodeExport::writeRetraction(RetractionConfig* config, bool force, bool ext
     }
     else
     {
-        double speed = ((retraction_diff_e_amount < 0.0)? config->speed : extr_attr.last_retraction_prime_speed) * 60;
+        double speed = ((retraction_diff_e_amount < 0.0)? config.speed : extr_attr.last_retraction_prime_speed) * 60;
         current_e_value += retraction_diff_e_amount;
         *output_stream << "G1 F" << PrecisionedDouble{1, speed} << " "
             << extr_attr.extruderCharacter << PrecisionedDouble{5, current_e_value} << new_line;
         currentSpeed = speed;
         estimateCalculator.plan(TimeEstimateCalculator::Position(INT2MM(currentPosition.x), INT2MM(currentPosition.y), INT2MM(currentPosition.z), eToMm(current_e_value)), currentSpeed);
-        extr_attr.last_retraction_prime_speed = config->primeSpeed;
+        extr_attr.last_retraction_prime_speed = config.primeSpeed;
     }
 
     extr_attr.retraction_e_amount_current = new_retraction_e_amount; // suppose that for UM2 the retraction amount in the firmware is equal to the provided amount
-    extr_attr.prime_volume += config->prime_volume;
+    extr_attr.prime_volume += config.prime_volume;
 
 }
 
@@ -709,6 +728,16 @@ void GCodeExport::writeZhopStart(int hop_height)
     {
         isZHopped = hop_height;
         *output_stream << "G1 Z" << MMtoStream{currentPosition.z + isZHopped} << new_line;
+        total_bounding_box.includeZ(currentPosition.z + isZHopped);
+    }
+}
+
+void GCodeExport::writeZhopEnd()
+{
+    if (isZHopped)
+    {
+        isZHopped = 0;
+        *output_stream << "G1 Z" << MMtoStream{currentPosition.z} << new_line;
     }
 }
 
@@ -746,7 +775,7 @@ void GCodeExport::switchExtruder(int new_extruder, const RetractionConfig& retra
 
     bool force = true;
     bool extruder_switch = true;
-    writeRetraction(&const_cast<RetractionConfig&>(retraction_config_old_extruder), force, extruder_switch);
+    writeRetraction(const_cast<RetractionConfig&>(retraction_config_old_extruder), force, extruder_switch);
 
     resetExtrusionValue(); // zero the E value on the old extruder, so that the current_e_value is registered on the old extruder
 
@@ -813,7 +842,12 @@ void GCodeExport::writeTemperatureCommand(int extruder, double temperature, bool
 {
     if (!wait && extruder_attr[extruder].currentTemperature == temperature)
         return;
-    
+
+    if (flavor == EGCodeFlavor::ULTIGCODE)
+    { // The UM2 family doesn't support temperature commands (they are fixed in the firmware)
+        return;
+    }
+
     if (wait)
         *output_stream << "M109";
     else
@@ -829,6 +863,11 @@ void GCodeExport::writeTemperatureCommand(int extruder, double temperature, bool
 
 void GCodeExport::writeBedTemperatureCommand(double temperature, bool wait)
 {
+    if (flavor == EGCodeFlavor::ULTIGCODE)
+    { // The UM2 family doesn't support temperature commands (they are fixed in the firmware)
+        return;
+    }
+
     if (wait)
         *output_stream << "M190 S";
     else
@@ -868,7 +907,7 @@ void GCodeExport::writeMaxZFeedrate(double max_z_feedrate)
 {
     if (current_max_z_feedrate != max_z_feedrate)
     {
-        *output_stream << "M203 Z" << int(max_z_feedrate * 60) << new_line;
+        *output_stream << "M203 Z" << PrecisionedDouble{2, max_z_feedrate} << new_line;
         current_max_z_feedrate = max_z_feedrate;
         estimateCalculator.setMaxZFeedrate(max_z_feedrate);
     }

src/gcodeExport.h

@@ -99,6 +99,8 @@ private:
     double current_jerk; //!< The current jerk in the XY direction (in mm/s^3)
     double current_max_z_feedrate; //!< The current max z speed
 
+    AABB3D total_bounding_box; //!< The bounding box of all g-code.
+
     /*!
      * The z position to be used on the next xy move, if the head wasn't in the correct z position yet.
      * 
@@ -259,7 +261,7 @@ private:
      */
     void writeMoveBFB(int x, int y, int z, double speed, double extrusion_mm3_per_mm);
 public:
-    void writeRetraction(RetractionConfig* config, bool force = false, bool extruder_switch = false);
+    void writeRetraction(const RetractionConfig& config, bool force = false, bool extruder_switch = false);
 
     /*!
      * Start a z hop with the given \p hop_height
@@ -268,6 +270,12 @@ public:
      */
     void writeZhopStart(int hop_height);
 
+    /*!
+     * End a z hop: go back to the layer height
+     * 
+     */
+    void writeZhopEnd();
+
     /*!
      * Start the new_extruder: 
      * - set new extruder
@@ -341,13 +349,17 @@ public:
      * See FffGcodeWriter::processStartingCode
      * 
      * \param settings The meshgroup to get the global bed temp from and to get the extruder trains from which to get the nozzle temperatures
+     * \param start_extruder_nr The extruder with which to start this print
      */
-    void setInitialTemps(const MeshGroup& settings);
+    void setInitialTemps(const MeshGroup& settings, const unsigned int start_extruder_nr);
 
     /*!
      * Override or set an initial nozzle temperature as written by GCodeExport::setInitialTemps
      * This is used primarily during better specification of temperatures in LayerPlanBuffer::insertPreheatCommand
      * 
+     * \warning This function must be called before any of the layers in the meshgroup are written to file!
+     * That's because it sets the current temperature in the gcode!
+     * 
      * \param extruder_nr The extruder number for which to better specify the temp
      * \param temp The temp at which the nozzle should be at startup
      */

src/gcodePlanner.cpp

@@ -5,28 +5,19 @@
 #include "sliceDataStorage.h"
 #include "utils/polygonUtils.h"
 #include "MergeInfillLines.h"
+#include "raft.h" // getTotalExtraLayers
 
 namespace cura {
 
-TimeMaterialEstimates TimeMaterialEstimates::operator-(const TimeMaterialEstimates& other)
-{
-    return TimeMaterialEstimates(extrude_time - other.extrude_time,unretracted_travel_time - other.unretracted_travel_time,retracted_travel_time - other.retracted_travel_time,material - other.material);
-}
 
-TimeMaterialEstimates& TimeMaterialEstimates::operator-=(const TimeMaterialEstimates& other)
-{
-    extrude_time -= other.extrude_time;
-    unretracted_travel_time -= other.unretracted_travel_time;
-    retracted_travel_time -= other.retracted_travel_time;
-    material -= other.material;
-    return *this;
-}
-
-ExtruderPlan::ExtruderPlan(int extruder, Point start_position, int layer_nr, int layer_thickness, FanSpeedLayerTimeSettings& fan_speed_layer_time_settings, const RetractionConfig& retraction_config)
+ExtruderPlan::ExtruderPlan(int extruder, Point start_position, int layer_nr, bool is_initial_layer, int layer_thickness, FanSpeedLayerTimeSettings& fan_speed_layer_time_settings, const RetractionConfig& retraction_config)
 : extruder(extruder)
-, required_temp(-1)
+, heated_pre_travel_time(0)
+, initial_printing_temperature(-1)
+, printing_temperature(-1)
 , start_position(start_position)
 , layer_nr(layer_nr)
+, is_initial_layer(is_initial_layer)
 , layer_thickness(layer_thickness)
 , fan_speed_layer_time_settings(fan_speed_layer_time_settings)
 , retraction_config(retraction_config)
@@ -73,6 +64,7 @@ GCodePath* GCodePlanner::getLatestPathWithConfig(GCodePathConfig* config, SpaceF
     paths.emplace_back();
     GCodePath* ret = &paths.back();
     ret->retract = false;
+    ret->perform_prime = false;
     ret->perform_z_hop = false;
     ret->config = config;
     ret->done = false;
@@ -89,9 +81,10 @@ void GCodePlanner::forceNewPathStart()
         paths[paths.size()-1].done = true;
 }
 
-GCodePlanner::GCodePlanner(SliceDataStorage& storage, unsigned int layer_nr, int z, int layer_thickness, Point last_position, int current_extruder, bool is_inside_mesh, std::vector<FanSpeedLayerTimeSettings>& fan_speed_layer_time_settings_per_extruder, CombingMode combing_mode, int64_t comb_boundary_offset, bool travel_avoid_other_parts, int64_t travel_avoid_distance)
+GCodePlanner::GCodePlanner(SliceDataStorage& storage, int layer_nr, int z, int layer_thickness, Point last_position, int current_extruder, bool is_inside_mesh, std::vector<FanSpeedLayerTimeSettings>& fan_speed_layer_time_settings_per_extruder, CombingMode combing_mode, int64_t comb_boundary_offset, bool travel_avoid_other_parts, int64_t travel_avoid_distance)
 : storage(storage)
 , layer_nr(layer_nr)
+, is_initial_layer(layer_nr == 0 - Raft::getTotalExtraLayers(storage))
 , z(z)
 , layer_thickness(layer_thickness)
 , start_position(last_position)
@@ -102,7 +95,7 @@ GCodePlanner::GCodePlanner(SliceDataStorage& storage, unsigned int layer_nr, int
 , fan_speed_layer_time_settings_per_extruder(fan_speed_layer_time_settings_per_extruder)
 {
     extruder_plans.reserve(storage.meshgroup->getExtruderCount());
-    extruder_plans.emplace_back(current_extruder, start_position, layer_nr, layer_thickness, fan_speed_layer_time_settings_per_extruder[current_extruder], storage.retraction_config_per_extruder[current_extruder]);
+    extruder_plans.emplace_back(current_extruder, start_position, layer_nr, is_initial_layer, layer_thickness, fan_speed_layer_time_settings_per_extruder[current_extruder], storage.retraction_config_per_extruder[current_extruder]);
     comb = nullptr;
     was_inside = is_inside_mesh; 
     is_inside = false; // assumes the next move will not be to inside a layer part (overwritten just before going into a layer part)
@@ -202,7 +195,8 @@ bool GCodePlanner::setExtruder(int extruder)
     }
     else 
     {
-        extruder_plans.emplace_back(extruder, lastPosition, layer_nr, layer_thickness, fan_speed_layer_time_settings_per_extruder[extruder], storage.retraction_config_per_extruder[extruder]);
+        extruder_plans.emplace_back(extruder, lastPosition, layer_nr, is_initial_layer, layer_thickness, fan_speed_layer_time_settings_per_extruder[extruder], storage.retraction_config_per_extruder[extruder]);
+        assert((int)extruder_plans.size() <= storage.meshgroup->getExtruderCount() && "Never use the same extruder twice on one layer!");
     }
     last_planned_extruder_setting_base = storage.meshgroup->getExtruderTrain(extruder);
 
@@ -244,7 +238,7 @@ void GCodePlanner::moveInsideCombBoundary(int distance)
     }
 }
 
-void GCodePlanner::addTravel(Point p)
+GCodePath& GCodePlanner::addTravel(Point p)
 {
     GCodePath* path = nullptr;
     GCodePathConfig& travel_config = storage.travel_config_per_extruder[getExtruder()];
@@ -330,11 +324,12 @@ void GCodePlanner::addTravel(Point p)
         }
     }
 
-    addTravel_simple(p, path);
+    GCodePath& ret = addTravel_simple(p, path);
     was_inside = is_inside;
+    return ret;
 }
 
-void GCodePlanner::addTravel_simple(Point p, GCodePath* path)
+GCodePath& GCodePlanner::addTravel_simple(Point p, GCodePath* path)
 {
     if (path == nullptr)
     {
@@ -342,8 +337,17 @@ void GCodePlanner::addTravel_simple(Point p, GCodePath* path)
     }
     path->points.push_back(p);
     lastPosition = p;
+    return *path;
 }
 
+void GCodePlanner::planPrime()
+{
+    forceNewPathStart();
+    GCodePath& prime_travel = addTravel_simple(lastPosition + Point(0, 100));
+    prime_travel.retract = false;
+    prime_travel.perform_prime = true;
+    forceNewPathStart();
+}
 
 void GCodePlanner::addExtrusionMove(Point p, GCodePathConfig* config, SpaceFillType space_fill_type, float flow, bool spiralize)
 {
@@ -351,22 +355,47 @@ void GCodePlanner::addExtrusionMove(Point p, GCodePathConfig* config, SpaceFillT
     lastPosition = p;
 }
 
-void GCodePlanner::addPolygon(PolygonRef polygon, int startIdx, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, bool spiralize)
+void GCodePlanner::addPolygon(PolygonRef polygon, int start_idx, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, coord_t wall_0_wipe_dist, bool spiralize)
 {
-    Point p0 = polygon[startIdx];
+    Point p0 = polygon[start_idx];
     addTravel(p0);
-    for(unsigned int i=1; i<polygon.size(); i++)
+    for (unsigned int point_idx = 1; point_idx < polygon.size(); point_idx++)
     {
-        Point p1 = polygon[(startIdx + i) % polygon.size()];
+        Point p1 = polygon[(start_idx + point_idx) % polygon.size()];
         float flow = (wall_overlap_computation)? wall_overlap_computation->getFlow(p0, p1) : 1.0;
         addExtrusionMove(p1, config, SpaceFillType::Polygons, flow, spiralize);
         p0 = p1;
     }
     if (polygon.size() > 2)
     {
-        Point& p1 = polygon[startIdx];
+        Point& p1 = polygon[start_idx];
         float flow = (wall_overlap_computation)? wall_overlap_computation->getFlow(p0, p1) : 1.0;
         addExtrusionMove(p1, config, SpaceFillType::Polygons, flow, spiralize);
+
+        if (wall_0_wipe_dist > 0)
+        { // apply outer wall wipe
+            p0 = polygon[start_idx];
+            int distance_traversed = 0;
+            for (unsigned int point_idx = 1; ; point_idx++)
+            {
+                Point p1 = polygon[(start_idx + point_idx) % polygon.size()];
+                int p0p1_dist = vSize(p1 - p0);
+                if (distance_traversed + p0p1_dist >= wall_0_wipe_dist)
+                {
+                    Point vector = p1 - p0;
+                    Point half_way = p0 + normal(vector, wall_0_wipe_dist - distance_traversed);
+                    addTravel_simple(half_way);
+                    break;
+                }
+                else
+                {
+                    addTravel_simple(p1);
+                    distance_traversed += p0p1_dist;
+                }
+                p0 = p1;
+            }
+            forceNewPathStart();
+        }
     }
     else 
     {
@@ -374,13 +403,13 @@ void GCodePlanner::addPolygon(PolygonRef polygon, int startIdx, GCodePathConfig*
     }
 }
 
-void GCodePlanner::addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, EZSeamType z_seam_type, bool spiralize)
+void GCodePlanner::addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, EZSeamType z_seam_type, Point z_seam_pos, coord_t wall_0_wipe_dist, bool spiralize)
 {
     if (polygons.size() == 0)
     {
         return;
     }
-    PathOrderOptimizer orderOptimizer(lastPosition, z_seam_type);
+    PathOrderOptimizer orderOptimizer(lastPosition, z_seam_pos, z_seam_type);
     for (unsigned int poly_idx = 0; poly_idx < polygons.size(); poly_idx++)
     {
         orderOptimizer.addPolygon(polygons[poly_idx]);
@@ -388,7 +417,7 @@ void GCodePlanner::addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* c
     orderOptimizer.optimize();
     for (unsigned int poly_idx : orderOptimizer.polyOrder)
     {
-        addPolygon(polygons[poly_idx], orderOptimizer.polyStart[poly_idx], config, wall_overlap_computation, spiralize);
+        addPolygon(polygons[poly_idx], orderOptimizer.polyStart[poly_idx], config, wall_overlap_computation, wall_0_wipe_dist, spiralize);
     }
 }
 void GCodePlanner::addLinesByOptimizer(Polygons& polygons, GCodePathConfig* config, SpaceFillType space_fill_type, int wipe_dist)
@@ -563,22 +592,23 @@ void ExtruderPlan::processFanSpeedAndMinimalLayerTime(bool force_minimal_layer_t
     }
     /*
     Supposing no influence of minimal layer time; i.e. layer time > min layer time fan speed min:
-    
-           max..   fan 'full' on layer
-                |  :
-                |  :
-      ^    min..|..:________________
-     fan        |  / 
-    speed       | / 
-          zero..|/__________________
-                  layer nr >
-                  
-       
+
+              max..   fan 'full' on layer
+                   |  :
+                   |  :
+      ^       min..|..:________________
+     fan           |  /
+    speed          | /
+          speed_0..|/
+                   |
+                   |__________________
+                     layer nr >
+
     */
     if (layer_nr < fsml.cool_fan_full_layer)
     {
         //Slow down the fan on the layers below the [cool_fan_full_layer], where layer 0 is speed 0.
-        fan_speed = fan_speed * std::max(0, layer_nr) / fsml.cool_fan_full_layer;
+        fan_speed = fsml.cool_fan_speed_0 + (fan_speed - fsml.cool_fan_speed_0) * std::max(0, layer_nr) / fsml.cool_fan_full_layer;
     }
 }
 
@@ -613,7 +643,13 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
     gcode.setLayerNr(layer_nr);
     
     gcode.writeLayerComment(layer_nr);
-    
+
+    if (layer_nr == 1 - Raft::getTotalExtraLayers(storage))
+    {
+        bool wait = false;
+        gcode.writeBedTemperatureCommand(storage.getSettingInDegreeCelsius("material_bed_temperature"), wait);
+    }
+
     gcode.setZ(z);
     
     
@@ -642,19 +678,29 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
 
             { // require printing temperature to be met
                 constexpr bool wait = true;
-                gcode.writeTemperatureCommand(extruder, extruder_plan.required_temp, wait);
+                gcode.writeTemperatureCommand(extruder, extruder_plan.initial_printing_temperature, wait);
             }
 
             // prime extruder if it hadn't been used yet
             gcode.writePrimeTrain(storage.meshgroup->getExtruderTrain(extruder)->getSettingInMillimetersPerSecond("speed_travel"));
-            gcode.writeRetraction(&retraction_config);
+            gcode.writeRetraction(retraction_config);
 
             if (extruder_plan.prev_extruder_standby_temp)
             { // turn off previous extruder
                 constexpr bool wait = false;
-                gcode.writeTemperatureCommand(prev_extruder, *extruder_plan.prev_extruder_standby_temp, wait);
+                double prev_extruder_temp = *extruder_plan.prev_extruder_standby_temp;
+                int prev_layer_nr = (extruder_plan_idx == 0)? layer_nr - 1 : layer_nr;
+                if (prev_layer_nr == storage.max_print_height_per_extruder[prev_extruder])
+                {
+                    prev_extruder_temp = 0; // TODO ? should there be a setting for extruder_off_temperature ?
+                }
+                gcode.writeTemperatureCommand(prev_extruder, prev_extruder_temp, wait);
             }
         }
+        else if (extruder_plan_idx == 0 && layer_nr != 0 && storage.meshgroup->getExtruderTrain(extruder)->getSettingBoolean("retract_at_layer_change"))
+        {
+            gcode.writeRetraction(retraction_config);
+        }
         gcode.writeFanCommand(extruder_plan.getFanSpeed());
         std::vector<GCodePath>& paths = extruder_plan.paths;
 
@@ -677,6 +723,12 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
             
             GCodePath& path = paths[path_idx];
 
+            if (path.perform_prime)
+            {
+                gcode.writePrimeTrain(train->getSettingInMillimetersPerSecond("speed_travel"));
+                gcode.writeRetraction(retraction_config);
+            }
+
             if (acceleration_enabled)
             {
                 gcode.writeAcceleration(path.config->getAcceleration());
@@ -688,11 +740,15 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
 
             if (path.retract)
             {
-                gcode.writeRetraction(&retraction_config);
+                gcode.writeRetraction(retraction_config);
                 if (path.perform_z_hop)
                 {
                     gcode.writeZhopStart(retraction_config.zHop);
                 }
+                else
+                {
+                    gcode.writeZhopEnd();
+                }
             }
             if (!path.config->isTravelPath() && last_extrusion_config != path.config)
             {
@@ -803,7 +859,7 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
         {
             gcode.writeComment("Small layer, adding delay");
             RetractionConfig& retraction_config = storage.retraction_config_per_extruder[gcode.getExtruderNr()];
-            gcode.writeRetraction(&retraction_config);
+            gcode.writeRetraction(retraction_config);
             if (extruder_plan_idx == extruder_plans.size() - 1 || !train->getSettingBoolean("machine_extruder_end_pos_abs"))
             { // only move the head if it's the last extruder plan; otherwise it's already at the switching bay area 
                 // or do it anyway when we switch extruder in-place

src/gcodePlanner.h

@@ -6,6 +6,9 @@
 
 #include "gcodeExport.h"
 #include "pathPlanning/Comb.h"
+#include "pathPlanning/GCodePath.h"
+#include "pathPlanning/NozzleTempInsert.h"
+#include "pathPlanning/TimeMaterialEstimates.h"
 #include "utils/polygon.h"
 #include "utils/logoutput.h"
 #include "wallOverlap.h"
@@ -21,249 +24,6 @@ namespace cura
 
 class SliceDataStorage;
 
-/*!
- * A gcode command to insert before a specific path.
- * 
- * Currently only used for preheat commands
- */
-struct NozzleTempInsert
-{
-    const unsigned int path_idx; //!< The path before which to insert this command
-    double time_after_path_start; //!< The time after the start of the path, before which to insert the command // TODO: use this to insert command in between moves in a path!
-    int extruder; //!< The extruder for which to set the temp
-    double temperature; //!< The temperature of the temperature command to insert
-    bool wait; //!< Whether to wait for the temperature to be reached
-    NozzleTempInsert(unsigned int path_idx, int extruder, double temperature, bool wait, double time_after_path_start = 0.0)
-    : path_idx(path_idx)
-    , time_after_path_start(time_after_path_start)
-    , extruder(extruder)
-    , temperature(temperature)
-    , wait(wait)
-    {}
-    
-    /*!
-     * Write the temperature command at the current position in the gcode.
-     * \param gcode The actual gcode writer
-     */
-    void write(GCodeExport& gcode)
-    {
-        gcode.writeTemperatureCommand(extruder, temperature, wait);
-    }
-};
-
-class ExtruderPlan; // forward declaration so that TimeMaterialEstimates can be a friend
-
-
-/*!
- * Time and material estimates for a portion of paths, e.g. layer, extruder plan, path.
- */
-class TimeMaterialEstimates
-{
-    friend class ExtruderPlan; // cause there the naive estimates are calculated
-private:
-    double extrude_time; //!< Time in seconds occupied by extrusion
-    double unretracted_travel_time; //!< Time in seconds occupied by non-retracted travel (non-extrusion)
-    double retracted_travel_time; //!< Time in seconds occupied by retracted travel (non-extrusion)
-    double material; //!< Material used (in mm^3)
-public:
-    /*!
-     * Basic contructor
-     * 
-     * \param extrude_time Time in seconds occupied by extrusion
-     * \param unretracted_travel_time Time in seconds occupied by non-retracted travel (non-extrusion)
-     * \param retracted_travel_time Time in seconds occupied by retracted travel (non-extrusion)
-     * \param material Material used (in mm^3)
-     */
-    TimeMaterialEstimates(double extrude_time, double unretracted_travel_time, double retracted_travel_time, double material)
-    : extrude_time(extrude_time)
-    , unretracted_travel_time(unretracted_travel_time)
-    , retracted_travel_time(retracted_travel_time)
-    , material(material)
-    {
-    }
-
-    /*!
-     * Basic constructor initializing all estimates to zero.
-     */
-    TimeMaterialEstimates()
-    : extrude_time(0.0)
-    , unretracted_travel_time(0.0)
-    , retracted_travel_time(0.0)
-    , material(0.0)
-    {
-    }
-
-    /*!
-     * Set all estimates to zero.
-     */
-    void reset() 
-    {
-        extrude_time = 0.0;
-        unretracted_travel_time = 0.0;
-        retracted_travel_time = 0.0;
-        material = 0.0;
-    }
-
-    /*!
-     * Pointwise addition of estimate stats
-     * 
-     * \param other The estimates to add to these estimates.
-     * \return The resulting estimates
-     */
-    TimeMaterialEstimates operator+(const TimeMaterialEstimates& other)
-    {
-        return TimeMaterialEstimates(extrude_time+other.extrude_time, unretracted_travel_time+other.unretracted_travel_time, retracted_travel_time+other.retracted_travel_time, material+other.material);
-    }
-
-    /*!
-     * In place pointwise addition of estimate stats
-     * 
-     * \param other The estimates to add to these estimates.
-     * \return These estimates
-     */
-    TimeMaterialEstimates& operator+=(const TimeMaterialEstimates& other)
-    {
-        extrude_time += other.extrude_time;
-        unretracted_travel_time += other.unretracted_travel_time;
-        retracted_travel_time += other.retracted_travel_time;
-        material += other.material;
-        return *this;
-    }
-
-    /*!
-     * \brief Subtracts the specified estimates from these estimates and returns
-     * the result.
-     * 
-     * Each of the estimates in this class are individually subtracted.
-     * 
-     * \param other The estimates to subtract from these estimates.
-     * \return These estimates with the specified estimates subtracted.
-     */
-    TimeMaterialEstimates operator-(const TimeMaterialEstimates& other);
-
-    /*!
-     * \brief Subtracts the specified elements from these estimates.
-     * 
-     * This causes the estimates in this instance to change. Each of the
-     * estimates in this class are individually subtracted.
-     * 
-     * \param other The estimates to subtract from these estimates.
-     * \return A reference to this instance.
-     */
-    TimeMaterialEstimates& operator-=(const TimeMaterialEstimates& other);
-
-    /*!
-     * Get total time estimate. The different time estimate member values added together.
-     * 
-     * \return the total of all different time estimate values 
-     */
-    double getTotalTime() const
-    {
-        return extrude_time + unretracted_travel_time + retracted_travel_time;
-    }
-
-    /*!
-     * Get the total time during which the head is not retracted.
-     * 
-     * This includes extrusion time and non-retracted travel time
-     * 
-     * \return the total time during which the head is not retracted.
-     */
-    double getTotalUnretractedTime() const
-    {
-        return extrude_time + unretracted_travel_time;
-    }
-
-    /*!
-     * Get the total travel time.
-     * 
-     * This includes the retracted travel time as well as the unretracted travel time.
-     * 
-     * \return the total travel time.
-     */
-    double getTravelTime() const
-    {
-        return retracted_travel_time + unretracted_travel_time;
-    }
-
-    /*!
-     * Get the extrusion time.
-     * 
-     * \return extrusion time.
-     */
-    double getExtrudeTime() const
-    {
-        return extrude_time;
-    }
-
-    /*!
-     * Get the amount of material used in mm^3.
-     * 
-     * \return amount of material
-     */
-    double getMaterial() const
-    {
-        return material;
-    }
-};
-
-/*!
- * A class for representing a planned path.
- * 
- * A path consists of several segments of the same type of movement: retracted travel, infill extrusion, etc.
- * 
- * This is a compact premature representation in which are line segments have the same config, i.e. the config of this path.
- * 
- * In the final representation (gcode) each line segment may have different properties, 
- * which are added when the generated GCodePaths are processed.
- */
-class GCodePath
-{
-public:
-    GCodePathConfig* config; //!< The configuration settings of the path.
-    SpaceFillType space_fill_type; //!< The type of space filling of which this path is a part
-    float flow; //!< A type-independent flow configuration (used for wall overlap compensation)
-    bool retract; //!< Whether the path is a move path preceded by a retraction move; whether the path is a retracted move path. 
-    bool perform_z_hop; //!< Whether to perform a z_hop in this path, which is assumed to be a travel path.
-    std::vector<Point> points; //!< The points constituting this path.
-    bool done;//!< Path is finished, no more moves should be added, and a new path should be started instead of any appending done to this one.
-
-    bool spiralize; //!< Whether to gradually increment the z position during the printing of this path. A sequence of spiralized paths should start at the given layer height and end in one layer higher.
-
-    TimeMaterialEstimates estimates; //!< Naive time and material estimates
-
-    /*!
-     * Whether this config is the config of a travel path.
-     * 
-     * \return Whether this config is the config of a travel path.
-     */
-    bool isTravelPath()
-    {
-        return config->isTravelPath();
-    }
-
-    /*!
-     * Get the material flow in mm^3 per mm traversed.
-     * 
-     * \warning Can only be called after the layer height has been set (which is done while writing the gcode!)
-     * 
-     * \return The flow
-     */
-    double getExtrusionMM3perMM()
-    {
-        return flow * config->getExtrusionMM3perMM();
-    }
-    
-    /*!
-     * Get the actual line width (modulated by the flow)
-     * \return the actual line width as shown in layer view
-     */
-    int getLineWidth()
-    {
-        return flow * config->getLineWidth() * config->getFlowPercentage() / 100.0;
-    }
-};
-
 class GCodePlanner; // forward declaration so that ExtruderPlan can be a friend
 class LayerPlanBuffer; // forward declaration so that ExtruderPlan can be a friend
 
@@ -281,7 +41,10 @@ protected:
     std::list<NozzleTempInsert> inserts; //!< The nozzle temperature command inserts, to be inserted in between paths
 
     int extruder; //!< The extruder used for this paths in the current plan.
-    double required_temp; //!< The required temperature at the start of this extruder plan.
+    double heated_pre_travel_time; //!< The time at the start of this ExtruderPlan during which the head travels and has a temperature of initial_print_temperature
+    double initial_printing_temperature; //!< The required temperature at the start of this extruder plan.
+    double printing_temperature; //!< The normal temperature for printing this extruder plan. That start and end of this extruder plan may deviate because of the initial and final print temp
+    std::optional<std::list<NozzleTempInsert>::iterator> printing_temperature_command; //!< The command to heat from the printing temperature of this extruder plan to the printing temperature of the next extruder plan (if it has the same extruder).
     std::optional<double> prev_extruder_standby_temp; //!< The temperature to which to set the previous extruder. Not used if the previous extruder plan was the same extruder.
 
     TimeMaterialEstimates estimates; //!< Accumulated time and material estimates for all planned paths within this extruder plan.
@@ -294,7 +57,7 @@ public:
      * \param extruder The extruder number for which this object is a plan.
      * \param start_position The position the head is when this extruder plan starts
      */
-    ExtruderPlan(int extruder, Point start_position, int layer_nr, int layer_thickness, FanSpeedLayerTimeSettings& fan_speed_layer_time_settings, const RetractionConfig& retraction_config);
+    ExtruderPlan(int extruder, Point start_position, int layer_nr, bool is_initial_layer, int layer_thickness, FanSpeedLayerTimeSettings& fan_speed_layer_time_settings, const RetractionConfig& retraction_config);
 
     /*!
      * Add a new Insert, constructed with the given arguments
@@ -398,6 +161,8 @@ protected:
     Point start_position; //!< The position the print head was at at the start of this extruder plan
 
     int layer_nr; //!< The layer number at which we are currently printing.
+    bool is_initial_layer; //!< Whether this extruder plan is printed on the very first layer (which might be raft)
+
     int layer_thickness; //!< The thickness of this layer in Z-direction
 
     FanSpeedLayerTimeSettings& fan_speed_layer_time_settings; //!< The fan speed and layer time settings used to limit this extruder plan
@@ -454,6 +219,7 @@ private:
     SliceDataStorage& storage; //!< The polygon data obtained from FffPolygonProcessor
 
     int layer_nr; //!< The layer number of this layer plan
+    int is_initial_layer; //!< Whether this is the first layer (which might be raft)
     
     int z; 
     
@@ -486,7 +252,8 @@ private:
      * \return A path with the given config which is now the last path in GCodePlanner::paths
      */
     GCodePath* getLatestPathWithConfig(GCodePathConfig* config, SpaceFillType space_fill_type, float flow = 1.0, bool spiralize = false);
-    
+
+public:
     /*!
      * Force GCodePlanner::getLatestPathWithConfig to return a new path.
      * 
@@ -498,7 +265,7 @@ private:
      * - when changing extruder, the same travel config is used, but its extruder field is changed.
      */
     void forceNewPathStart();
-public:
+
     /*!
      * 
      * \param fan_speed_layer_time_settings_per_extruder The fan speed and layer time settings for each extruder.
@@ -507,7 +274,7 @@ public:
      * \param last_position The position of the head at the start of this gcode layer
      * \param combing_mode Whether combing is enabled and full or within infill only.
      */
-    GCodePlanner(SliceDataStorage& storage, unsigned int layer_nr, int z, int layer_height, Point last_position, int current_extruder, bool is_inside_mesh, std::vector<FanSpeedLayerTimeSettings>& fan_speed_layer_time_settings_per_extruder, CombingMode combing_mode, int64_t comb_boundary_offset, bool travel_avoid_other_parts, int64_t travel_avoid_distance);
+    GCodePlanner(SliceDataStorage& storage, int layer_nr, int z, int layer_height, Point last_position, int current_extruder, bool is_inside_mesh, std::vector<FanSpeedLayerTimeSettings>& fan_speed_layer_time_settings_per_extruder, CombingMode combing_mode, int64_t comb_boundary_offset, bool travel_avoid_other_parts, int64_t travel_avoid_distance);
     ~GCodePlanner();
 
     void overrideFanSpeeds(double speed);
@@ -557,7 +324,13 @@ public:
     * Features like prime tower and support are considered outside.
     */
     void setIsInside(bool going_to_comb);
-    
+
+    /*!
+     * Plan a switch to a new extruder
+     * 
+     * \param extruder The extruder number to which to switch
+     * \return whether the extruder has changed
+     */
     bool setExtruder(int extruder);
 
     /*!
@@ -576,7 +349,7 @@ public:
      * 
      * \param p The point to travel to
      */
-    void addTravel(Point p);
+    GCodePath& addTravel(Point p);
     
     /*!
      * Add a travel path to a certain point and retract if needed.
@@ -586,7 +359,14 @@ public:
      * \param p The point to travel to
      * \param path (optional) The travel path to which to add the point \p p
      */
-    void addTravel_simple(Point p, GCodePath* path = nullptr);
+    GCodePath& addTravel_simple(Point p, GCodePath* path = nullptr);
+
+    /*!
+     * Plan a prime poop at the current location.
+     * 
+     * \warning A nonretracted move is introduced so that the LayerPlanBuffer classifies this move as an extrusion move.
+     */
+    void planPrime();
 
     /*!
      * Add an extrusion move to a certain point, optionally with a different flow than the one in the \p config.
@@ -605,9 +385,10 @@ public:
      * \param startIdx The index of the starting vertex of the \p polygon
      * \param config The config with which to print the polygon lines
      * \param wall_overlap_computation The wall overlap compensation calculator for each given segment (optionally nullptr)
+     * \param wall_0_wipe_dist The distance to travel along the polygon after it has been laid down, in order to wipe the start and end of the wall together
      * \param spiralize Whether to gradually increase the z height from the normal layer height to the height of the next layer over this polygon
      */
-    void addPolygon(PolygonRef polygon, int startIdx, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation = nullptr, bool spiralize = false);
+    void addPolygon(PolygonRef polygon, int startIdx, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation = nullptr, coord_t wall_0_wipe_dist = 0, bool spiralize = false);
 
     /*!
      * Add polygons to the gcode with optimized order.
@@ -622,9 +403,11 @@ public:
      * \param config The config with which to print the polygon lines
      * \param wall_overlap_computation The wall overlap compensation calculator for each given segment (optionally nullptr)
      * \param z_seam_type The seam type / poly start optimizer
+     * \param z_seam_pos The location near where to start each part in case \p z_seam_type is 'back'
+     * \param wall_0_wipe_dist The distance to travel along each polygon after it has been laid down, in order to wipe the start and end of the wall together
      * \param spiralize Whether to gradually increase the z height from the normal layer height to the height of the next layer over each polygon printed
      */
-    void addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation = nullptr, EZSeamType z_seam_type = EZSeamType::SHORTEST, bool spiralize = false);
+    void addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation = nullptr, EZSeamType z_seam_type = EZSeamType::SHORTEST, Point z_seam_pos = Point(0, 0), coord_t wall_0_wipe_dist = 0, bool spiralize = false);
 
     /*!
      * Add lines to the gcode with optimized order.

src/infill.cpp

@@ -17,11 +17,10 @@ int Infill::computeScanSegmentIdx(int x, int line_width)
     return x / line_width;
 }
 
-void Infill::generate(Polygons& result_polygons, Polygons& result_lines)
+void Infill::generate(Polygons& result_polygons, Polygons& result_lines, SliceMeshStorage* mesh)
 {
     if (in_outline.size() == 0) return;
     if (line_distance == 0) return;
-    const Polygons* outline = &in_outline;
     Polygons outline_offsetted;
     switch(pattern)
     {
@@ -41,28 +40,75 @@ void Infill::generate(Polygons& result_polygons, Polygons& result_lines)
         generateTriangleInfill(result_lines);
         break;
     case EFillMethod::CONCENTRIC:
-        outline_offsetted = in_outline.offset(outline_offset - infill_line_width / 2); // - infill_line_width / 2 cause generateConcentricInfill expects [outline] to be the outer most polygon instead of the outer outline 
-        outline = &outline_offsetted;
-        generateConcentricInfill(*outline, result_polygons, line_distance);
+        generateConcentricInfill(result_polygons, line_distance);
+        break;
+    case EFillMethod::CONCENTRIC_3D:
+        generateConcentric3DInfill(result_polygons);
         break;
     case EFillMethod::ZIG_ZAG:
         generateZigZagInfill(result_lines, line_distance, fill_angle, connected_zigzags, use_endpieces);
         break;
+    case EFillMethod::CUBICSUBDIV:
+        if (!mesh)
+        {
+            logError("Cannot generate Cubic Subdivision infill without a mesh!\n");
+            break;
+        }
+        generateCubicSubDivInfill(result_lines, *mesh);
+        break;
     default:
         logError("Fill pattern has unknown value.\n");
         break;
     }
 }
 
-void Infill::generateConcentricInfill(Polygons outline, Polygons& result, int inset_value)
+void Infill::generateConcentricInfill(Polygons& result, int inset_value)
 {
-    while(outline.size() > 0)
+    Polygons first_concentric_wall = in_outline.offset(outline_offset - line_distance + infill_line_width / 2); // - infill_line_width / 2 cause generateConcentricInfill expects [outline] to be the outer most polygon instead of the outer outline
+
+    if (perimeter_gaps)
     {
-        result.add(outline);
-        outline = outline.offset(-inset_value);
-    } 
+        const Polygons inner = first_concentric_wall.offset(infill_line_width / 2 + perimeter_gaps_extra_offset);
+        const Polygons gaps_here = in_outline.difference(inner);
+        perimeter_gaps->add(gaps_here);
+    }
+    generateConcentricInfill(first_concentric_wall, result, inset_value);
 }
 
+void Infill::generateConcentricInfill(Polygons& first_concentric_wall, Polygons& result, int inset_value)
+{
+    result.add(first_concentric_wall);
+    Polygons* prev_inset = &first_concentric_wall;
+    Polygons next_inset;
+    while (prev_inset->size() > 0)
+    {
+        next_inset = prev_inset->offset(-inset_value);
+        result.add(next_inset);
+        if (perimeter_gaps)
+        {
+            const Polygons outer = prev_inset->offset(-infill_line_width / 2 - perimeter_gaps_extra_offset);
+            const Polygons inner = next_inset.offset(infill_line_width / 2);
+            const Polygons gaps_here = outer.difference(inner);
+            perimeter_gaps->add(gaps_here);
+        }
+        prev_inset = &next_inset;
+    }
+}
+
+void Infill::generateConcentric3DInfill(Polygons& result)
+{
+    int period = line_distance * 2;
+    int shift = int64_t(one_over_sqrt_2 * z) % period;
+    shift = std::min(shift, period - shift); // symmetry due to the fact that we are applying the shift in both directions
+    shift = std::min(shift, period / 2 - infill_line_width / 2); // don't put lines too close to each other
+    shift = std::max(shift, infill_line_width / 2); // don't put lines too close to each other
+    Polygons first_wall;
+    // in contrast to concentric infill we dont do "- infill_line_width / 2" cause this is already handled by the max two lines above
+    first_wall = in_outline.offset(outline_offset - shift);
+    generateConcentricInfill(first_wall, result, period);
+    first_wall = in_outline.offset(outline_offset - period + shift);
+    generateConcentricInfill(first_wall, result, period);
+}
 
 void Infill::generateGridInfill(Polygons& result)
 {
@@ -80,14 +126,15 @@ void Infill::generateCubicInfill(Polygons& result)
 
 void Infill::generateTetrahedralInfill(Polygons& result)
 {
-    int shift = int64_t(one_over_sqrt_2 * z) % line_distance;
-    shift = std::min(shift, line_distance - shift); // symmetry due to the fact that we are applying the shift in both directions
-    shift = std::min(shift, line_distance / 2 - infill_line_width / 2); // don't put lines too close to each other
+    int period = line_distance * 2;
+    int shift = int64_t(one_over_sqrt_2 * z) % period;
+    shift = std::min(shift, period - shift); // symmetry due to the fact that we are applying the shift in both directions
+    shift = std::min(shift, period / 2 - infill_line_width / 2); // don't put lines too close to each other
     shift = std::max(shift, infill_line_width / 2); // don't put lines too close to each other
-    generateLineInfill(result, line_distance, fill_angle, shift);
-    generateLineInfill(result, line_distance, fill_angle, -shift);
-    generateLineInfill(result, line_distance, fill_angle + 90, shift);
-    generateLineInfill(result, line_distance, fill_angle + 90, -shift);
+    generateLineInfill(result, period, fill_angle, shift);
+    generateLineInfill(result, period, fill_angle, -shift);
+    generateLineInfill(result, period, fill_angle + 90, shift);
+    generateLineInfill(result, period, fill_angle + 90, -shift);
 }
 
 void Infill::generateTriangleInfill(Polygons& result)
@@ -97,15 +144,26 @@ void Infill::generateTriangleInfill(Polygons& result)
     generateLineInfill(result, line_distance, fill_angle + 120, 0);
 }
 
+void Infill::generateCubicSubDivInfill(Polygons& result, SliceMeshStorage& mesh)
+{
+    Polygons uncropped;
+    mesh.base_subdiv_cube->generateSubdivisionLines(z, uncropped);
+    addLineSegmentsInfill(result, uncropped);
+}
+
+void Infill::addLineSegmentsInfill(Polygons& result, Polygons& input)
+{
+    ClipperLib::PolyTree interior_segments_tree = in_outline.lineSegmentIntersection(input);
+    ClipperLib::Paths interior_segments;
+    ClipperLib::OpenPathsFromPolyTree(interior_segments_tree, interior_segments);
+    for (uint64_t idx = 0; idx < interior_segments.size(); idx++)
+    {
+        result.addLine(interior_segments[idx][0], interior_segments[idx][1]);
+    }
+}
+
 void Infill::addLineInfill(Polygons& result, const PointMatrix& rotation_matrix, const int scanline_min_idx, const int line_distance, const AABB boundary, std::vector<std::vector<int64_t>>& cut_list, int64_t shift)
 {
-    auto addLine = [&](Point from, Point to)
-    {
-        PolygonRef p = result.newPoly();
-        p.add(rotation_matrix.unapply(from));
-        p.add(rotation_matrix.unapply(to));
-    };
-
     auto compare_int64_t = [](const void* a, const void* b)
     {
         int64_t n = (*(int64_t*)a) - (*(int64_t*)b);
@@ -131,7 +189,7 @@ void Infill::addLineInfill(Polygons& result, const PointMatrix& rotation_matrix,
             { // segment is too short to create infill
                 continue;
             }
-            addLine(Point(x, crossings[crossing_idx]), Point(x, crossings[crossing_idx + 1]));
+            result.addLine(rotation_matrix.unapply(Point(x, crossings[crossing_idx])), rotation_matrix.unapply(Point(x, crossings[crossing_idx + 1])));
         }
         scanline_idx += 1;
     }
@@ -210,14 +268,18 @@ void Infill::generateLinearBasedInfill(const int outline_offset, Polygons& resul
     if (outline_offset != 0)
     {
         outline = in_outline.offset(outline_offset);
+        if (perimeter_gaps)
+        {
+            perimeter_gaps->add(in_outline.difference(outline.offset(infill_line_width / 2 + perimeter_gaps_extra_offset)));
+        }
     }
     else
     {
         outline = in_outline;
     }
-    
-        outline = outline.offset(infill_overlap);
-    
+
+    outline = outline.offset(infill_overlap);
+
     if (outline.size() == 0)
     {
         return;

src/infill.h

@@ -12,6 +12,7 @@
 #include "infill/ZigzagConnectorProcessorEndPieces.h"
 #include "infill/ZigzagConnectorProcessorConnectedEndPieces.h"
 #include "infill/ZigzagConnectorProcessorDisconnectedEndPieces.h"
+#include "infill/SubDivCube.h"
 #include "utils/intpoint.h"
 #include "utils/AABB.h"
 
@@ -20,6 +21,8 @@ namespace cura
 
 class Infill 
 {
+    static constexpr int perimeter_gaps_extra_offset = 15; // extra offset so that the perimeter gaps aren't created everywhere due to rounding errors
+
     EFillMethod pattern; //!< the space filling pattern of the infill to generate
     const Polygons& in_outline; //!< a reference polygon for getting the actual area within which to generate infill (see outline_offset)
     int outline_offset; //!< Offset from Infill::in_outline to get the actual area within which to generate infill
@@ -29,12 +32,33 @@ class Infill
     double fill_angle; //!< for linear infill types: the angle of the infill lines (or the angle of the grid)
     int64_t z; //!< height of the layer for which we generate infill
     int64_t shift; //!< shift of the scanlines in the direction perpendicular to the fill_angle
+    Polygons* perimeter_gaps; //!< (optional output) The areas in between consecutive insets when Concentric infill is used.
     bool connected_zigzags; //!< (ZigZag) Whether endpieces of zigzag infill should be connected to the nearest infill line on both sides of the zigzag connector
     bool use_endpieces; //!< (ZigZag) Whether to include endpieces: zigzag connector segments from one infill line to itself
 
     static constexpr double one_over_sqrt_2 = 0.7071067811865475244008443621048490392848359376884740; //!< 1.0 / sqrt(2.0)
 public:
-    Infill(EFillMethod pattern, const Polygons& in_outline, int outline_offset, int infill_line_width, int line_distance, int infill_overlap, double fill_angle, int64_t z, int64_t shift, bool connected_zigzags = false, bool use_endpieces = false)
+    /*!
+     * \warning If \p perimeter_gaps is given, then the difference between the \p in_outline
+     * and the polygons which result from offsetting it by the \p outline_offset
+     * and then expanding it again by half the \p infill_line_width
+     * is added to the \p perimeter_gaps
+     * 
+     * \param[out] perimeter_gaps (optional output) The areas in between consecutive insets when Concentric infill is used.
+     */
+    Infill(EFillMethod pattern
+        , const Polygons& in_outline
+        , int outline_offset
+        , int infill_line_width
+        , int line_distance
+        , int infill_overlap
+        , double fill_angle
+        , int64_t z
+        , int64_t shift
+        , Polygons* perimeter_gaps = nullptr
+        , bool connected_zigzags = false
+        , bool use_endpieces = false
+    )
     : pattern(pattern)
     , in_outline(in_outline)
     , outline_offset(outline_offset)
@@ -44,6 +68,7 @@ public:
     , fill_angle(fill_angle)
     , z(z)
     , shift(shift)
+    , perimeter_gaps(perimeter_gaps)
     , connected_zigzags(connected_zigzags)
     , use_endpieces(use_endpieces)
     {
@@ -53,8 +78,9 @@ public:
      * 
      * \param result_polygons (output) The resulting polygons (from concentric infill)
      * \param result_lines (output) The resulting line segments (from linear infill types)
+     * \param mesh The mesh for which to geenrate infill (should only be used for non-helper objects)
      */
-    void generate(Polygons& result_polygons, Polygons& result_lines);
+    void generate(Polygons& result_polygons, Polygons& result_lines, SliceMeshStorage* mesh = nullptr);
 
 private:
     /*!
@@ -68,13 +94,30 @@ private:
      * \param line_distance the width of the scan segments
      */
     static inline int computeScanSegmentIdx(int x, int line_distance);
+
     /*!
-     * Generate sparse concentric infill 
-     * \param outline The actual outline of the area within which to generate infill
+     * Generate sparse concentric infill
+     * 
+     * Also adds \ref Inifll::perimeter_gaps between \ref Infill::in_outline and the first wall
+     * 
      * \param result (output) The resulting polygons
      * \param inset_value The offset between each consecutive two polygons
      */
-    void generateConcentricInfill(Polygons outline, Polygons& result, int inset_value);
+    void generateConcentricInfill(Polygons& result, int inset_value);
+
+    /*!
+     * Generate sparse concentric infill starting from a specific outer wall
+     * \param first_wall The outer wall from which to start
+     * \param result (output) The resulting polygons
+     * \param inset_value The offset between each consecutive two polygons
+     */
+    void generateConcentricInfill(Polygons& first_wall, Polygons& result, int inset_value);
+
+    /*!
+     * Generate sparse concentric infill 
+     * \param result (output) The resulting polygons
+     */
+    void generateConcentric3DInfill(Polygons& result);
 
     /*!
      * Generate a rectangular grid of infill lines
@@ -99,6 +142,13 @@ private:
      * \param result (output) The resulting lines
      */
     void generateTriangleInfill(Polygons& result);
+
+    /*!
+     * Generate a 3d pattern of subdivided cubes on their points
+     * \param[out] result The resulting lines
+     * \param[in] mesh Where the Cubic Subdivision Infill precomputation is stored
+     */
+    void generateCubicSubDivInfill(Polygons& result, SliceMeshStorage& mesh);
     
     /*!
      * Convert a mapping from scanline to line_segment-scanline-intersections (\p cut_list) into line segments, using the even-odd rule
@@ -112,6 +162,13 @@ private:
      */
     void addLineInfill(Polygons& result, const PointMatrix& rotation_matrix, const int scanline_min_idx, const int line_distance, const AABB boundary, std::vector<std::vector<int64_t>>& cut_list, int64_t total_shift);
 
+    /*!
+     * Crop line segments by the infill polygon using Clipper
+     * \param result (output) The resulting lines
+     * \param input The line segments to be cropped
+     */
+    void addLineSegmentsInfill(Polygons& result, Polygons& input);
+
     /*!
      * generate lines within the area of \p in_outline, at regular intervals of \p line_distance
      * 

src/infill/SubDivCube.cpp

@@ -0,0 +1,282 @@
+#include "SubDivCube.h"
+
+#include <functional>
+
+#include "../utils/polygonUtils.h"
+#include "../sliceDataStorage.h"
+#include "../utils/math.h"
+
+#define ONE_OVER_SQRT_2 0.7071067811865475244008443621048490392848359376884740 //1 / sqrt(2)
+#define ONE_OVER_SQRT_3 0.577350269189625764509148780501957455647601751270126876018 //1 / sqrt(3)
+#define ONE_OVER_SQRT_6 0.408248290463863016366214012450981898660991246776111688072 //1 / sqrt(6)
+#define SQRT_TWO_THIRD 0.816496580927726032732428024901963797321982493552223376144 //sqrt(2 / 3)
+
+namespace cura
+{
+
+std::vector<SubDivCube::CubeProperties> SubDivCube::cube_properties_per_recursion_step;
+double SubDivCube::radius_multiplier = 1;
+int32_t SubDivCube::radius_addition = 0;
+Point3Matrix SubDivCube::rotation_matrix;
+PointMatrix SubDivCube::infill_rotation_matrix;
+
+SubDivCube::~SubDivCube()
+{
+    for (int child_idx = 0; child_idx < 8; child_idx++)
+    {
+        if (children[child_idx])
+        {
+            delete children[child_idx];
+        }
+    }
+}
+
+void SubDivCube::precomputeOctree(SliceMeshStorage& mesh)
+{
+    radius_multiplier = mesh.getSettingAsRatio("sub_div_rad_mult");
+    radius_addition = mesh.getSettingInMicrons("sub_div_rad_add");
+    double infill_angle = M_PI / 4.0;
+
+    coord_t furthest_dist_from_origin = std::sqrt(square(mesh.getSettingInMicrons("machine_height")) + square(mesh.getSettingInMicrons("machine_depth") / 2) + square(mesh.getSettingInMicrons("machine_width") / 2));
+    coord_t max_side_length = furthest_dist_from_origin * 2;
+
+    int curr_recursion_depth = 0;
+    const int64_t infill_line_distance = mesh.getSettingInMicrons("infill_line_distance");
+    if (infill_line_distance > 0)
+    {
+        for (int64_t curr_side_length = infill_line_distance * 2; curr_side_length < max_side_length * 2; curr_side_length *= 2)
+        {
+            cube_properties_per_recursion_step.emplace_back();
+            CubeProperties& cube_properties_here = cube_properties_per_recursion_step.back();
+            cube_properties_here.side_length = curr_side_length;
+            cube_properties_here.height = sqrt(3) * curr_side_length;
+            cube_properties_here.square_height = sqrt(2) * curr_side_length;
+            cube_properties_here.max_draw_z_diff = ONE_OVER_SQRT_3 * curr_side_length;
+            cube_properties_here.max_line_offset = ONE_OVER_SQRT_6 * curr_side_length;
+            curr_recursion_depth++;
+        }
+    }
+    Point3 center(0, 0, 0);
+
+    Point3Matrix tilt; // rotation matrix to get from axis aligned cubes to cubes standing on their tip
+    // The Z axis is transformed to go in positive Y direction
+    //
+    //  cross section in a horizontal plane      horizontal plane showing
+    //  looking down at the origin O             positive X and positive Y
+    //                 Z                                                        .
+    //                /:\                              Y                        .
+    //               / : \                             ^                        .
+    //              /  :  \                            |                        .
+    //             /  .O.  \                           |                        .
+    //            /.~'   '~.\                          O---->X                  .
+    //          X """"""""""" Y                                                 .
+    tilt.matrix[0] = -ONE_OVER_SQRT_2;  tilt.matrix[1] = ONE_OVER_SQRT_2; tilt.matrix[2] = 0;
+    tilt.matrix[3] = -ONE_OVER_SQRT_6; tilt.matrix[4] = -ONE_OVER_SQRT_6; tilt.matrix[5] = SQRT_TWO_THIRD ;
+    tilt.matrix[6] = ONE_OVER_SQRT_3;  tilt.matrix[7] = ONE_OVER_SQRT_3;  tilt.matrix[8] = ONE_OVER_SQRT_3;
+
+    infill_rotation_matrix = PointMatrix(infill_angle);
+    Point3Matrix infill_angle_mat(infill_rotation_matrix);
+
+    rotation_matrix = infill_angle_mat.compose(tilt);
+
+    mesh.base_subdiv_cube = new SubDivCube(mesh, center, curr_recursion_depth - 1);
+}
+
+void SubDivCube::generateSubdivisionLines(int64_t z, Polygons& result)
+{
+    if (cube_properties_per_recursion_step.empty()) //Infill is set to 0%.
+    {
+        return;
+    }
+    Polygons directional_line_groups[3];
+
+    generateSubdivisionLines(z, result, directional_line_groups);
+
+    for (int dir_idx = 0; dir_idx < 3; dir_idx++)
+    {
+        Polygons& line_group = directional_line_groups[dir_idx];
+        for (unsigned int line_idx = 0; line_idx < line_group.size(); line_idx++)
+        {
+            result.addLine(line_group[line_idx][0], line_group[line_idx][1]);
+        }
+    }
+}
+
+void SubDivCube::generateSubdivisionLines(int64_t z, Polygons& result, Polygons (&directional_line_groups)[3])
+{
+    CubeProperties cube_properties = cube_properties_per_recursion_step[depth];
+
+    int32_t z_diff = std::abs(z - center.z); //!< the difference between the cube center and the target layer.
+    if (z_diff > cube_properties.height / 2) //!< this cube does not touch the target layer. Early exit.
+    {
+        return;
+    }
+    if (z_diff < cube_properties.max_draw_z_diff) //!< this cube has lines that need to be drawn.
+    {
+        Point relative_a, relative_b; //!< relative coordinates of line endpoints around cube center
+        Point a, b; //!< absolute coordinates of line endpoints
+        relative_a.X = (cube_properties.square_height / 2) * (cube_properties.max_draw_z_diff - z_diff) / cube_properties.max_draw_z_diff;
+        relative_b.X = -relative_a.X;
+        relative_a.Y = cube_properties.max_line_offset - ((z - (center.z - cube_properties.max_draw_z_diff)) * ONE_OVER_SQRT_2);
+        relative_b.Y = relative_a.Y;
+        rotatePointInitial(relative_a);
+        rotatePointInitial(relative_b);
+        for (int dir_idx = 0; dir_idx < 3; dir_idx++)//!< draw the line, then rotate 120 degrees.
+        {
+            a.X = center.x + relative_a.X;
+            a.Y = center.y + relative_a.Y;
+            b.X = center.x + relative_b.X;
+            b.Y = center.y + relative_b.Y;
+            addLineAndCombine(directional_line_groups[dir_idx], a, b);
+            if (dir_idx < 2)
+            {
+                rotatePoint120(relative_a);
+                rotatePoint120(relative_b);
+            }
+        }
+    }
+    for (int idx = 0; idx < 8; idx++) //!< draws the eight children
+    {
+        if (children[idx] != nullptr)
+        {
+            children[idx]->generateSubdivisionLines(z, result, directional_line_groups);
+        }
+    }
+}
+
+SubDivCube::SubDivCube(SliceMeshStorage& mesh, Point3& center, unsigned int depth)
+{
+    this->depth = depth;
+    this->center = center;
+
+    if (depth == 0) // lowest layer, no need for subdivision, exit.
+    {
+        return;
+    }
+    if (depth >= cube_properties_per_recursion_step.size()) //Depth is out of bounds of what we pre-computed.
+    {
+        return;
+    }
+
+    CubeProperties cube_properties = cube_properties_per_recursion_step[depth];
+    Point3 child_center;
+    coord_t radius = double(radius_multiplier * double(cube_properties.height)) / 4.0 + radius_addition;
+
+    int child_nr = 0;
+    std::vector<Point3> rel_child_centers;
+    rel_child_centers.emplace_back(1, 1, 1); // top
+    rel_child_centers.emplace_back(-1, 1, 1); // top three
+    rel_child_centers.emplace_back(1, -1, 1);
+    rel_child_centers.emplace_back(1, 1, -1);
+    rel_child_centers.emplace_back(-1, -1, -1); // bottom
+    rel_child_centers.emplace_back(1, -1, -1); // bottom three
+    rel_child_centers.emplace_back(-1, 1, -1);
+    rel_child_centers.emplace_back(-1, -1, 1);
+    for (Point3 rel_child_center : rel_child_centers)
+    {
+        child_center = center + rotation_matrix.apply(rel_child_center * int32_t(cube_properties.side_length / 4));
+        if (isValidSubdivision(mesh, child_center, radius))
+        {
+            children[child_nr] = new SubDivCube(mesh, child_center, depth - 1);
+            child_nr++;
+        }
+    }
+}
+
+bool SubDivCube::isValidSubdivision(SliceMeshStorage& mesh, Point3& center, int64_t radius)
+{
+    int64_t distance2;
+    long int sphere_slice_radius2;//!< squared radius of bounding sphere slice on target layer
+    bool inside_somewhere = false;
+    bool outside_somewhere = false;
+    int inside;
+    double part_dist;//what percentage of the radius the target layer is away from the center along the z axis. 0 - 1
+    const long int layer_height = mesh.getSettingInMicrons("layer_height");
+    long int bottom_layer = (center.z - radius) / layer_height;
+    long int top_layer = (center.z + radius) / layer_height;
+    for (long int test_layer = bottom_layer; test_layer <= top_layer; test_layer += 3) // steps of three. Low-hanging speed gain.
+    {
+        part_dist = (double)(test_layer * layer_height - center.z) / radius;
+        sphere_slice_radius2 = radius * radius * (1.0 - (part_dist * part_dist));
+        Point loc(center.x, center.y);
+
+        inside = distanceFromPointToMesh(mesh, test_layer, loc, &distance2);
+        if (inside == 1)
+        {
+            inside_somewhere = true;
+        }
+        else
+        {
+            outside_somewhere = true;
+        }
+        if (outside_somewhere && inside_somewhere)
+        {
+            return true;
+        }
+        if ((inside != 2) && distance2 < sphere_slice_radius2)
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+int SubDivCube::distanceFromPointToMesh(SliceMeshStorage& mesh, long int layer_nr, Point& location, int64_t* distance2)
+{
+    if (layer_nr < 0 || (unsigned long int)layer_nr >= mesh.layers.size()) //!< this layer is outside of valid range
+    {
+        return 2;
+    }
+    Polygons collide;
+    mesh.layers[layer_nr].getSecondOrInnermostWalls(collide);
+    Point centerpoint = location;
+    bool inside = collide.inside(centerpoint);
+    ClosestPolygonPoint border_point = PolygonUtils::moveInside2(collide, centerpoint);
+    Point diff = border_point.location - location;
+    *distance2 = vSize2(diff);
+    if (inside)
+    {
+        return 1;
+    }
+    return 0;
+}
+
+
+void SubDivCube::rotatePointInitial(Point& target)
+{
+    target = infill_rotation_matrix.apply(target);
+}
+
+void SubDivCube::rotatePoint120(Point& target)
+{
+    constexpr double sqrt_three_fourths = 0.8660254037844386467637231707529361834714026269051903; //!< sqrt(3.0 / 4.0) = sqrt(3) / 2
+    int64_t x;
+    x = (-0.5) * target.X - sqrt_three_fourths * target.Y;
+    target.Y = (-0.5)*target.Y + sqrt_three_fourths * target.X;
+    target.X = x;
+}
+
+void SubDivCube::addLineAndCombine(Polygons& group, Point from, Point to)
+{
+    int epsilon = 10; // the smallest distance of two points which are viewed as coincident (dist > 0 due to rounding errors)
+    for (unsigned int idx = 0; idx < group.size(); idx++)
+    {
+        if (std::abs(from.X - group[idx][1].X) < epsilon && std::abs(from.Y - group[idx][1].Y) < epsilon)
+        {
+            from = group[idx][0];
+            group.remove(idx);
+            idx--;
+            continue;
+        }
+        if (std::abs(to.X - group[idx][0].X) < epsilon && std::abs(to.Y - group[idx][0].Y) < epsilon)
+        {
+            to = group[idx][1];
+            group.remove(idx);
+            idx--;
+            continue;
+        }
+    }
+    group.addLine(from, to);
+}
+
+}//namespace cura

src/infill/SubDivCube.h

@@ -0,0 +1,98 @@
+#ifndef INFILL_SUBDIVCUBE_H
+#define INFILL_SUBDIVCUBE_H
+
+#include "../sliceDataStorage.h"
+
+namespace cura
+{
+
+class Infill;
+
+class SubDivCube
+{
+public:
+    /*!
+     * Constructor for SubDivCube. Recursively calls itself eight times to flesh out the octree.
+     * \param mesh contains infill layer data and settings
+     * \param my_center the center of the cube
+     * \param depth the recursion depth of the cube (0 is most recursed)
+     */
+    SubDivCube(SliceMeshStorage& mesh, Point3& center, unsigned int depth);
+
+    ~SubDivCube(); //!< destructor (also destroys children
+
+    /*!
+     * Precompute the octree of subdivided cubes
+     * \param mesh contains infill layer data and settings
+     */
+    static void precomputeOctree(SliceMeshStorage& mesh);
+    /*!
+     * Generates the lines of subdivision of the specific cube at the specific layer. It recursively calls itself, so it ends up drawing all the subdivision lines of sub-cubes too.
+     * \param z the specified layer height
+     * \param result (output) The resulting lines
+     */
+    void generateSubdivisionLines(int64_t z, Polygons& result);
+private:
+    /*!
+     * Generates the lines of subdivision of the specific cube at the specific layer. It recursively calls itself, so it ends up drawing all the subdivision lines of sub-cubes too.
+     * \param z the specified layer height
+     * \param result (output) The resulting lines
+     * \param directional_line_groups Array of 3 times a polylines. Used to keep track of line segments that are all pointing the same direction for line segment combining
+     */
+    void generateSubdivisionLines(int64_t z, Polygons& result, Polygons (&directional_line_groups)[3]);
+    struct CubeProperties
+    {
+        int64_t side_length; //!< side length of cubes
+        int64_t height; //!< height of cubes based. This is the distance from one point of a cube to its 3d opposite.
+        int64_t square_height; //!< square cut across lengths. This is the diagonal distance across a face of the cube.
+        int64_t max_draw_z_diff; //!< maximum draw z differences. This is the maximum difference in z at which lines need to be drawn.
+        int64_t max_line_offset; //!< maximum line offsets. This is the maximum distance at which subdivision lines should be drawn from the 2d cube center.
+    };
+    /*!
+     * Rotates a point 120 degrees about the origin.
+     * \param target the point to rotate.
+     */
+    static void rotatePoint120(Point& target);
+    /*!
+     * Rotates a point to align it with the orientation of the infill.
+     * \param target the point to rotate.
+     */
+    static void rotatePointInitial(Point& target);
+    /*!
+     * Determines if a described theoretical cube should be subdivided based on if a sphere that encloses the cube touches the infill mesh.
+     * \param mesh contains infill layer data and settings
+     * \param center the center of the described cube
+     * \param radius the radius of the enclosing sphere
+     * \return the described cube should be subdivided
+     */
+    static bool isValidSubdivision(SliceMeshStorage& mesh, Point3& center, int64_t radius);
+    /*!
+     * Finds the distance to the infill border at the specified layer from the specified point.
+     * \param mesh contains infill layer data and settings
+     * \param layer_nr the number of the specified layer
+     * \param location the location of the specified point
+     * \param[out] distance2 the squared distance to the infill border
+     * \return Code 0: outside, 1: inside, 2: boundary does not exist at specified layer
+     */
+    static int distanceFromPointToMesh(SliceMeshStorage& mesh, long int layer_nr, Point& location, int64_t* distance2);
+
+    /*!
+     * Adds the defined line to the specified polygons. It assumes that the specified polygons are all parallel lines. Combines line segments with touching ends closer than epsilon.
+     * \param[out] group the polygons to add the line to
+     * \param from the first endpoint of the line
+     * \param to the second endpoint of the line
+     */
+    void addLineAndCombine(Polygons& group, Point from, Point to);
+
+    unsigned int depth; //!< the recursion depth of the cube (0 is most recursed)
+    Point3 center; //!< center location of the cube in absolute coordinates
+    SubDivCube* children[8] = {nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr, nullptr}; //!< pointers to this cube's eight octree children
+    static std::vector<CubeProperties> cube_properties_per_recursion_step; //!< precomputed array of basic properties of cubes based on recursion depth.
+    static double radius_multiplier; //!< multiplier for the bounding radius when determining if a cube should be subdivided
+    static Point3Matrix rotation_matrix; //!< The rotation matrix to get from axis aligned cubes to cubes standing on a corner point aligned with the infill_angle
+    static PointMatrix infill_rotation_matrix; //!< Horizontal rotation applied to infill
+    static int32_t radius_addition; //!< addition to the bounding radius when determining if a cube should be subdivided
+};
+
+}
+#endif //INFILL_SUBDIVCUBE_H

src/infill/ZigzagConnectorProcessor.h

@@ -109,9 +109,7 @@ protected:
      */
     void addLine(Point from, Point to)
     {
-        PolygonRef line_poly = result.newPoly();
-        line_poly.add(rotation_matrix.unapply(from));
-        line_poly.add(rotation_matrix.unapply(to));
+        result.addLine(rotation_matrix.unapply(from), rotation_matrix.unapply(to));
     }
 
     /*!

src/layerPart.cpp

@@ -46,7 +46,6 @@ void createLayerParts(SliceMeshStorage& mesh, Slicer* slicer, bool union_layers,
 {
     for(unsigned int layer_nr = 0; layer_nr < slicer->layers.size(); layer_nr++)
     {
-        mesh.layers.push_back(SliceLayer());
         mesh.layers[layer_nr].sliceZ = slicer->layers[layer_nr].z;
         mesh.layers[layer_nr].printZ = slicer->layers[layer_nr].z;
         createLayerWithParts(mesh.layers[layer_nr], &slicer->layers[layer_nr], union_layers, union_all_remove_holes);

src/mesh.cpp

@@ -74,7 +74,10 @@ AABB3D Mesh::getAABB() const
 }
 void Mesh::expandXY(int64_t offset)
 {
-    aabb.expandXY(offset);
+    if (offset)
+    {
+        aabb.expandXY(offset);
+    }
 }
 
 

src/multiVolumes.cpp

@@ -3,20 +3,26 @@
 namespace cura 
 {
  
-void carveMultipleVolumes(std::vector<Slicer*> &volumes)
+void carveMultipleVolumes(std::vector<Slicer*> &volumes, bool alternate_carve_order)
 {
     //Go trough all the volumes, and remove the previous volume outlines from our own outline, so we never have overlapped areas.
-    for (unsigned int volume_1_idx = 0; volume_1_idx < volumes.size(); volume_1_idx++)
+    for (unsigned int volume_1_idx = 1; volume_1_idx < volumes.size(); volume_1_idx++)
     {
         Slicer& volume_1 = *volumes[volume_1_idx];
-        if (volume_1.mesh->getSettingBoolean("infill_mesh"))
+        if (volume_1.mesh->getSettingBoolean("infill_mesh") 
+            || volume_1.mesh->getSettingBoolean("anti_overhang_mesh")
+            || volume_1.mesh->getSettingBoolean("support_mesh")
+            )
         {
             continue;
         }
         for (unsigned int volume_2_idx = 0; volume_2_idx < volume_1_idx; volume_2_idx++)
         {
             Slicer& volume_2 = *volumes[volume_2_idx];
-            if (volume_2.mesh->getSettingBoolean("infill_mesh"))
+            if (volume_2.mesh->getSettingBoolean("infill_mesh")
+                || volume_2.mesh->getSettingBoolean("anti_overhang_mesh")
+                || volume_2.mesh->getSettingBoolean("support_mesh")
+                )
             {
                 continue;
             }
@@ -28,7 +34,14 @@ void carveMultipleVolumes(std::vector<Slicer*> &volumes)
             {
                 SlicerLayer& layer1 = volume_1.layers[layerNr];
                 SlicerLayer& layer2 = volume_2.layers[layerNr];
-                layer1.polygons = layer1.polygons.difference(layer2.polygons);
+                if (alternate_carve_order && layerNr % 2 == 0)
+                {
+                    layer2.polygons = layer2.polygons.difference(layer1.polygons);
+                }
+                else
+                {
+                    layer1.polygons = layer1.polygons.difference(layer2.polygons);
+                }
             }
         }
     }
@@ -48,6 +61,8 @@ void generateMultipleVolumesOverlap(std::vector<Slicer*> &volumes)
     {
         int overlap = volume->mesh->getSettingInMicrons("multiple_mesh_overlap");
         if (volume->mesh->getSettingBoolean("infill_mesh")
+            || volume->mesh->getSettingBoolean("anti_overhang_mesh")
+            || volume->mesh->getSettingBoolean("support_mesh")
             || overlap == 0)
         {
             continue;
@@ -60,6 +75,8 @@ void generateMultipleVolumesOverlap(std::vector<Slicer*> &volumes)
             for (Slicer* other_volume : volumes)
             {
                 if (other_volume->mesh->getSettingBoolean("infill_mesh")
+                    || other_volume->mesh->getSettingBoolean("anti_overhang_mesh")
+                    || other_volume->mesh->getSettingBoolean("support_mesh")
                     || !other_volume->mesh->getAABB().hit(aabb)
                     || other_volume == volume
                 )

src/multiVolumes.h

@@ -7,7 +7,11 @@
 /* This file contains code to help fixing up and changing layers that are build from multiple volumes. */
 namespace cura {
 
-void carveMultipleVolumes(std::vector<Slicer*> &meshes);
+/*!
+ * 
+ * \param alternate_carve_order Whether to switch which model carves out of which with every layer
+ */
+void carveMultipleVolumes(std::vector<Slicer*> &meshes, bool alternate_carve_order);
 
 /*!
  * Expand each layer a bit and then keep the extra overlapping parts that overlap with other volumes.

src/pathOrderOptimizer.cpp

@@ -92,7 +92,7 @@ int PathOrderOptimizer::getPolyStart(Point prev_point, int poly_idx)
 {
     switch (type)
     {
-        case EZSeamType::BACK:      return getFarthestPointInPolygon(poly_idx); 
+        case EZSeamType::BACK:      return getClosestPointInPolygon(z_seam_pos, poly_idx); 
         case EZSeamType::RANDOM:    return getRandomPointInPolygon(poly_idx); 
         case EZSeamType::SHORTEST:  return getClosestPointInPolygon(prev_point, poly_idx);
         default:                    return getClosestPointInPolygon(prev_point, poly_idx);
@@ -129,24 +129,6 @@ int PathOrderOptimizer::getRandomPointInPolygon(int poly_idx)
     return rand() % polygons[poly_idx].size();
 }
 
-
-int PathOrderOptimizer::getFarthestPointInPolygon(int poly_idx)
-{
-    PolygonRef poly = polygons[poly_idx];
-    int best_point_idx = -1;
-    float best_y = std::numeric_limits<float>::min();
-    for(unsigned int point_idx=0 ; point_idx<poly.size() ; point_idx++)
-    {
-        if (poly[point_idx].Y > best_y)
-        {
-            best_point_idx = point_idx;
-            best_y = poly[point_idx].Y;
-        }
-    }
-    return best_point_idx;
-}
-
-
 /**
 *
 */

src/pathOrderOptimizer.h

@@ -18,14 +18,16 @@ class PathOrderOptimizer
 {
 public:
     EZSeamType type;
-    Point startPoint; //!< The location of the nozzle before starting to print the current layer
+    Point startPoint; //!< A location near the prefered start location
+    Point z_seam_pos; //!< The position near where to create the z_seam (if \ref PathOrderOptimizer::type == 'back')
     std::vector<PolygonRef> polygons; //!< the parts of the layer (in arbitrary order)
     std::vector<int> polyStart; //!< polygons[i][polyStart[i]] = point of polygon i which is to be the starting point in printing the polygon
     std::vector<int> polyOrder; //!< the optimized order as indices in #polygons
 
-    PathOrderOptimizer(Point startPoint, EZSeamType type = EZSeamType::SHORTEST)
+    PathOrderOptimizer(Point startPoint, Point z_seam_pos = Point(0, 0), EZSeamType type = EZSeamType::SHORTEST)
     : type(type)
     , startPoint(startPoint)
+    , z_seam_pos(z_seam_pos)
     {
     }
 
@@ -43,9 +45,15 @@ public:
     void optimize(); //!< sets #polyStart and #polyOrder
 
 private:
+    /*!
+     * Get the starting vertex of a polygon, depending on the \ref PathOrderOptimizer::type
+     * \param prev_point The previous planned location
+     * \param poly_idx The index of the polygon in \ref PathOrderOptimizer::polygons
+     * \return the index of the starting vertex in \ref PathOrderOptimizer::polygons[\p poly_idx]
+     */
     int getPolyStart(Point prev_point, int poly_idx);
+
     int getClosestPointInPolygon(Point prev, int i_polygon); //!< returns the index of the closest point
-    int getFarthestPointInPolygon(int poly_idx); //!< return the index to the point farthest from the front (highest y)
     int getRandomPointInPolygon(int poly_idx);
 
 

src/pathPlanning/Comb.cpp

@@ -2,35 +2,25 @@
 #include "Comb.h"
 
 #include <algorithm>
+#include <functional> // function
+#include <unordered_set>
 
 #include "../utils/polygonUtils.h"
+#include "../utils/PolygonsPointIndex.h"
 #include "../sliceDataStorage.h"
 #include "../utils/SVG.h"
 
 namespace cura {
 
-
-// boundary_outside is only computed when it's needed!
-Polygons& Comb::getBoundaryOutside()
+LocToLineGrid& Comb::getOutsideLocToLine()
 {
-    if (!boundary_outside)
-    {
-        boundary_outside = new Polygons();
-        *boundary_outside = storage.getLayerOutlines(layer_nr, false).offset(offset_from_outlines_outside); 
-    }
-    return *boundary_outside;
-}
-
-SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>& Comb::getOutsideLocToLine()
-{
-    if (!outside_loc_to_line)
-    {
-        Polygons& outside = getBoundaryOutside();
-        outside_loc_to_line = PolygonUtils::createLocToLineGrid(outside, offset_from_inside_to_outside * 3 / 2);
-    }
     return *outside_loc_to_line;
 }
 
+Polygons& Comb::getBoundaryOutside()
+{
+    return *boundary_outside;
+}
   
 Comb::Comb(SliceDataStorage& storage, int layer_nr, Polygons& comb_boundary_inside, int64_t comb_boundary_offset, bool travel_avoid_other_parts, int64_t travel_avoid_distance)
 : storage(storage)
@@ -41,23 +31,31 @@ Comb::Comb(SliceDataStorage& storage, int layer_nr, Polygons& comb_boundary_insi
 , offset_from_inside_to_outside(offset_from_outlines + offset_from_outlines_outside)
 , max_crossing_dist2(offset_from_inside_to_outside * offset_from_inside_to_outside * 2) // so max_crossing_dist = offset_from_inside_to_outside * sqrt(2) =approx 1.5 to allow for slightly diagonal crossings and slightly inaccurate crossing computation
 , avoid_other_parts(travel_avoid_other_parts)
-// , boundary_inside( boundary.offset(-offset_from_outlines) ) // TODO: make inside boundary configurable?
 , boundary_inside( comb_boundary_inside )
-, boundary_outside(nullptr)
-, outside_loc_to_line(nullptr)
-, partsView_inside( boundary_inside.splitIntoPartsView() ) // !! changes the order of boundary_inside !!
+, partsView_inside( boundary_inside.splitIntoPartsView() ) // WARNING !! changes the order of boundary_inside !!
+, inside_loc_to_line(PolygonUtils::createLocToLineGrid(boundary_inside, comb_boundary_offset))
+, boundary_outside(
+        [&storage, layer_nr, travel_avoid_distance]()
+        {
+            return storage.getLayerOutlines(layer_nr, false).offset(travel_avoid_distance);
+        }
+    )
+, outside_loc_to_line(
+        [](Comb* comber, const int64_t offset_from_inside_to_outside)
+        {
+            return PolygonUtils::createLocToLineGrid(comber->getBoundaryOutside(), offset_from_inside_to_outside * 3 / 2);
+        }
+        , this
+        , offset_from_inside_to_outside
+    )
 {
 }
 
 Comb::~Comb()
 {
-    if (boundary_outside)
+    if (inside_loc_to_line)
     {
-        delete boundary_outside;
-    }
-    if (outside_loc_to_line)
-    {
-        delete outside_loc_to_line;
+        delete inside_loc_to_line;
     }
 }
 
@@ -84,7 +82,7 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
     { // normal combing within part
         PolygonsPart part = partsView_inside.assemblePart(start_part_idx);
         combPaths.emplace_back();
-        return LinePolygonsCrossings::comb(part, startPoint, endPoint, combPaths.back(), -offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
+        return LinePolygonsCrossings::comb(part, *inside_loc_to_line, startPoint, endPoint, combPaths.back(), -offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
     }
     else 
     { // comb inside part to edge (if needed) >> move through air avoiding other parts >> comb inside end part upto the endpoint (if needed) 
@@ -99,31 +97,31 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
             return false;
         }
 
-        Crossing start_crossing(startPoint, startInside, start_part_idx, start_part_boundary_poly_idx, boundary_inside);
-        Crossing end_crossing(endPoint, endInside, end_part_idx, end_part_boundary_poly_idx, boundary_inside);
+        Crossing start_crossing(startPoint, startInside, start_part_idx, start_part_boundary_poly_idx, boundary_inside, inside_loc_to_line);
+        Crossing end_crossing(endPoint, endInside, end_part_idx, end_part_boundary_poly_idx, boundary_inside, inside_loc_to_line);
 
         { // find crossing over the in-between area between inside and outside
             start_crossing.findCrossingInOrMid(partsView_inside, endPoint);
             end_crossing.findCrossingInOrMid(partsView_inside, start_crossing.in_or_mid);
         }
 
-        bool avoid_other_parts_now = avoid_other_parts;
-        if (avoid_other_parts_now && vSize2(start_crossing.in_or_mid - end_crossing.in_or_mid) < offset_from_inside_to_outside * offset_from_inside_to_outside * 4)
+        bool skip_avoid_other_parts_path = false;
+        if (skip_avoid_other_parts_path && vSize2(start_crossing.in_or_mid - end_crossing.in_or_mid) < offset_from_inside_to_outside * offset_from_inside_to_outside * 4)
         { // parts are next to eachother, i.e. the direct crossing will always be smaller than two crossings via outside
-            avoid_other_parts_now = false;
+            skip_avoid_other_parts_path = true;
         }
 
-        if (avoid_other_parts_now)
+        if (avoid_other_parts && !skip_avoid_other_parts_path)
         { // compute the crossing points when moving through air
-            Polygons& outside = getBoundaryOutside(); // comb through all air, since generally the outside consists of a single part
+            // comb through all air, since generally the outside consists of a single part
 
-            bool success = start_crossing.findOutside(outside, end_crossing.in_or_mid, fail_on_unavoidable_obstacles, *this);
+            bool success = start_crossing.findOutside(*boundary_outside, end_crossing.in_or_mid, fail_on_unavoidable_obstacles, *this);
             if (!success)
             {
                 return false;
             }
 
-            success = end_crossing.findOutside(outside, start_crossing.out, fail_on_unavoidable_obstacles, *this);
+            success = end_crossing.findOutside(*boundary_outside, start_crossing.out, fail_on_unavoidable_obstacles, *this);
             if (!success)
             {
                 return false;
@@ -136,7 +134,7 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
             // start to boundary
             assert(start_crossing.dest_part.size() > 0 && "The part we start inside when combing should have been computed already!");
             combPaths.emplace_back();
-            bool combing_succeeded = LinePolygonsCrossings::comb(start_crossing.dest_part, startPoint, start_crossing.in_or_mid, combPaths.back(), -offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
+            bool combing_succeeded = LinePolygonsCrossings::comb(start_crossing.dest_part, *inside_loc_to_line, startPoint, start_crossing.in_or_mid, combPaths.back(), -offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
             if (!combing_succeeded)
             { // Couldn't comb between start point and computed crossing from the start part! Happens for very thin parts when the offset_to_get_off_boundary moves points to outside the polygon
                 return false;
@@ -144,7 +142,7 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
         }
         
         // throught air from boundary to boundary
-        if (avoid_other_parts_now)
+        if (avoid_other_parts && !skip_avoid_other_parts_path)
         {
             combPaths.emplace_back();
             combPaths.throughAir = true;
@@ -155,7 +153,7 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
             }
             else
             {
-                bool combing_succeeded = LinePolygonsCrossings::comb(getBoundaryOutside(), start_crossing.out, end_crossing.out, combPaths.back(), offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
+                bool combing_succeeded = LinePolygonsCrossings::comb(*boundary_outside, *outside_loc_to_line, start_crossing.out, end_crossing.out, combPaths.back(), offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
                 if (!combing_succeeded)
                 {
                     return false;
@@ -166,10 +164,28 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
         { // directly through air (not avoiding other parts)
             combPaths.emplace_back();
             combPaths.throughAir = true;
-            combPaths.back().cross_boundary = true; // TODO: calculate whether we cross a boundary!
+            combPaths.back().cross_boundary = true; // note: we don't actually know whether this is cross boundary, but it might very well be
             combPaths.back().push_back(start_crossing.in_or_mid);
             combPaths.back().push_back(end_crossing.in_or_mid);
         }
+        if (skip_avoid_other_parts_path)
+        {
+            if (startInside == endInside && start_part_idx == end_part_idx)
+            {
+                if (startInside)
+                { // both start and end are inside
+                    combPaths.back().cross_boundary = PolygonUtils::polygonCollidesWithLineSegment(startPoint, endPoint, *inside_loc_to_line);
+                }
+                else
+                { // both start and end are outside
+                    combPaths.back().cross_boundary = PolygonUtils::polygonCollidesWithLineSegment(startPoint, endPoint, *outside_loc_to_line);
+                }
+            }
+            else
+            {
+                combPaths.back().cross_boundary = true;
+            }
+        }
         
         if (endInside)
         {
@@ -177,7 +193,7 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
             assert(end_crossing.dest_part.size() > 0 && "The part we end up inside when combing should have been computed already!");
             combPaths.emplace_back();
             
-            bool combing_succeeded = LinePolygonsCrossings::comb(end_crossing.dest_part, end_crossing.in_or_mid, endPoint, combPaths.back(), -offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
+            bool combing_succeeded = LinePolygonsCrossings::comb(end_crossing.dest_part, *inside_loc_to_line, end_crossing.in_or_mid, endPoint, combPaths.back(), -offset_dist_to_get_from_on_the_polygon_to_outside, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
             if (!combing_succeeded)
             { // Couldn't comb between end point and computed crossing to the end part! Happens for very thin parts when the offset_to_get_off_boundary moves points to outside the polygon
                 return false;
@@ -188,21 +204,25 @@ bool Comb::calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool _st
     }
 }
 
-Comb::Crossing::Crossing(const Point& dest_point, const bool dest_is_inside, const unsigned int dest_part_idx, const unsigned int dest_part_boundary_crossing_poly_idx, const Polygons& boundary_inside)
+Comb::Crossing::Crossing(const Point& dest_point, const bool dest_is_inside, const unsigned int dest_part_idx, const unsigned int dest_part_boundary_crossing_poly_idx, const Polygons& boundary_inside, const LocToLineGrid* inside_loc_to_line)
 : dest_is_inside(dest_is_inside)
-, dest_crossing_poly(boundary_inside[dest_part_boundary_crossing_poly_idx]) // initialize with most obvious poly, cause mostly a combing move will move outside the part, rather than inside a hole in the part
+, boundary_inside(boundary_inside)
+, inside_loc_to_line(inside_loc_to_line)
 , dest_point(dest_point)
 , dest_part_idx(dest_part_idx)
 {
-
+    if (dest_is_inside)
+    {
+        dest_crossing_poly = boundary_inside[dest_part_boundary_crossing_poly_idx]; // initialize with most obvious poly, cause mostly a combing move will move outside the part, rather than inside a hole in the part
+    }
 }
 
 bool Comb::moveInside(bool is_inside, Point& dest_point, unsigned int& inside_poly)
 {
     if (is_inside)
     {
-        ClosestPolygonPoint cpp = PolygonUtils::ensureInsideOrOutside(boundary_inside, dest_point, offset_extra_start_end, max_moveInside_distance2);
-        if (cpp.point_idx == NO_INDEX)
+        ClosestPolygonPoint cpp = PolygonUtils::ensureInsideOrOutside(boundary_inside, dest_point, offset_extra_start_end, max_moveInside_distance2, &boundary_inside, inside_loc_to_line);
+        if (!cpp.isValid())
         {
             return false;
         }
@@ -223,10 +243,43 @@ void Comb::Crossing::findCrossingInOrMid(const PartsView& partsView_inside, cons
         Point _dest_point(dest_point); // copy to local variable for lambda capture
         std::function<int(Point)> close_towards_start_penalty_function([_dest_point](Point candidate){ return vSize2((candidate - _dest_point) / 10); });
         dest_part = partsView_inside.assemblePart(dest_part_idx);
-        Point result(close_to);
+
+        ClosestPolygonPoint boundary_crossing_point;
+        { // set [result] to a point on the destination part closest to close_to (but also a bit close to _dest_point)
+            std::unordered_set<unsigned int> dest_part_poly_indices;
+            for (unsigned int poly_idx : partsView_inside[dest_part_idx])
+            {
+                dest_part_poly_indices.emplace(poly_idx);
+            }
+            coord_t dist2_score = std::numeric_limits<coord_t>::max();
+            std::function<bool (const PolygonsPointIndex&)> line_processor
+                = [close_to, _dest_point, &boundary_crossing_point, &dist2_score, &dest_part_poly_indices](const PolygonsPointIndex& boundary_segment)
+                {
+                    if (dest_part_poly_indices.find(boundary_segment.poly_idx) == dest_part_poly_indices.end())
+                    { // we're not looking at a polygon from the dest_part
+                        return true; // a.k.a. continue;
+                    }
+                    Point closest_here = LinearAlg2D::getClosestOnLineSegment(close_to, boundary_segment.p(), boundary_segment.next().p());
+                    coord_t dist2_score_here = vSize2(close_to - closest_here) + vSize2(_dest_point - closest_here) / 10;
+                    if (dist2_score_here < dist2_score)
+                    {
+                        dist2_score = dist2_score_here;
+                        boundary_crossing_point = ClosestPolygonPoint(closest_here, boundary_segment.point_idx, boundary_segment.getPolygon(), boundary_segment.poly_idx);
+                    }
+                    return true;
+                };
+            inside_loc_to_line->processLine(std::make_pair(dest_point, close_to), line_processor);
+        }
+
+        Point result(boundary_crossing_point.p()); // the inside point of the crossing
+        if (!boundary_crossing_point.isValid())
+        { // no point has been found in the sparse grid
+            result = dest_point;
+        }
+
         int64_t max_dist2 = std::numeric_limits<int64_t>::max();
-        ClosestPolygonPoint crossing_1_in_cp = PolygonUtils::ensureInsideOrOutside(dest_part, result, offset_dist_to_get_from_on_the_polygon_to_outside, max_dist2, close_towards_start_penalty_function);
-        if (crossing_1_in_cp.point_idx != NO_INDEX)
+        ClosestPolygonPoint crossing_1_in_cp = PolygonUtils::ensureInsideOrOutside(dest_part, result, boundary_crossing_point, offset_dist_to_get_from_on_the_polygon_to_outside, max_dist2, &boundary_inside, inside_loc_to_line, close_towards_start_penalty_function);
+        if (crossing_1_in_cp.isValid())
         {
             dest_crossing_poly = crossing_1_in_cp.poly;
             in_or_mid = result;
@@ -263,7 +316,8 @@ bool Comb::Crossing::findOutside(const Polygons& outside, const Point close_to,
     if (dest_is_inside && in_out_dist2_1 > comber.max_crossing_dist2) // moveInside moved too far
     { // if move is too far over in_between
         // find crossing closer by
-        std::shared_ptr<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> best = findBestCrossing(outside, dest_crossing_poly, dest_point, close_to, comber);
+        assert(dest_crossing_poly && "destination crossing poly should have been instantiated!");
+        std::shared_ptr<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> best = findBestCrossing(outside, *dest_crossing_poly, dest_point, close_to, comber);
         if (best)
         {
             in_or_mid = PolygonUtils::moveInside(best->first, comber.offset_dist_to_get_from_on_the_polygon_to_outside);

src/pathPlanning/Comb.h

@@ -4,9 +4,11 @@
 
 #include <memory> // shared_ptr
 
+#include "../utils/optional.h"
 #include "../utils/polygon.h"
 #include "../utils/SparsePointGridInclusive.h"
 #include "../utils/polygonUtils.h"
+#include "../utils/LazyInitialization.h"
 
 #include "LinePolygonsCrossings.h"
 #include "CombPath.h"
@@ -30,7 +32,7 @@ class SliceDataStorage;
  * As an optimization, the combing paths inside are calculated on specifically those PolygonsParts within which to comb, while the coundary_outside isn't split into outside parts, 
  * because generally there is only one outside part; encapsulated holes occur less often.
  */
-class Comb 
+class Comb
 {
     friend class LinePolygonsCrossings;
 private:
@@ -46,7 +48,9 @@ private:
         Point in_or_mid; //!< The point on the inside boundary, or in between the inside and outside boundary if the start/end point isn't inside the inside boudary
         Point out; //!< The point on the outside boundary
         PolygonsPart dest_part; //!< The assembled inside-boundary PolygonsPart in which the dest_point lies. (will only be initialized when Crossing::dest_is_inside holds)
-        PolygonRef dest_crossing_poly; //!< The polygon of the part in which dest_point lies, which will be crossed (often will be the outside polygon)
+        std::optional<PolygonRef> dest_crossing_poly; //!< The polygon of the part in which dest_point lies, which will be crossed (often will be the outside polygon)
+        const Polygons& boundary_inside; //!< The inside boundary as in \ref Comb::boundary_inside
+        const LocToLineGrid* inside_loc_to_line; //!< The loc to line grid \ref Comb::inside_loc_to_line
 
         /*!
          * Simple constructor
@@ -57,7 +61,7 @@ private:
          * \param dest_part_boundary_crossing_poly_idx The index in \p boundary_inside of the polygon of the part in which dest_point lies, which will be crossed (often will be the outside polygon).
          * \param boundary_inside The boundary within which to comb.
          */
-        Crossing(const Point& dest_point, const bool dest_is_inside, const unsigned int dest_part_idx, const unsigned int dest_part_boundary_crossing_poly_idx, const Polygons& boundary_inside);
+        Crossing(const Point& dest_point, const bool dest_is_inside, const unsigned int dest_part_idx, const unsigned int dest_part_boundary_crossing_poly_idx, const Polygons& boundary_inside, const LocToLineGrid* inside_loc_to_line);
 
         /*!
          * Find the not-outside location (Combing::in_or_mid) of the crossing between to the outside boundary
@@ -112,19 +116,20 @@ private:
     const bool avoid_other_parts; //!< Whether to perform inverse combing a.k.a. avoid parts.
     
     Polygons& boundary_inside; //!< The boundary within which to comb.
-    Polygons* boundary_outside; //!< The boundary outside of which to stay to avoid collision with other layer parts. This is a pointer cause we only compute it when we move outside the boundary (so not when there is only a single part in the layer)
-    SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>* outside_loc_to_line; //!< The SparsePointGridInclusive mapping locations to line segments of the outside boundary.
     PartsView partsView_inside; //!< Structured indices onto boundary_inside which shows which polygons belong to which part. 
+    LocToLineGrid* inside_loc_to_line; //!< The SparsePointGridInclusive mapping locations to line segments of the inner boundary.
+    LazyInitialization<Polygons> boundary_outside; //!< The boundary outside of which to stay to avoid collision with other layer parts. This is a pointer cause we only compute it when we move outside the boundary (so not when there is only a single part in the layer)
+    LazyInitialization<LocToLineGrid, Comb*, const int64_t> outside_loc_to_line; //!< The SparsePointGridInclusive mapping locations to line segments of the outside boundary.
 
-    /*!
-     * Get the boundary_outside, which is an offset from the outlines of all meshes in the layer. Calculate it when it hasn't been calculated yet.
-     */
-    Polygons& getBoundaryOutside();
-    
     /*!
      * Get the SparsePointGridInclusive mapping locations to line segments of the outside boundary. Calculate it when it hasn't been calculated yet.
      */
-    SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>& getOutsideLocToLine();
+    LocToLineGrid& getOutsideLocToLine();
+
+     /*!
+      * Get the boundary_outside, which is an offset from the outlines of all meshes in the layer. Calculate it when it hasn't been calculated yet.
+      */
+    Polygons& getBoundaryOutside();
 
     /*!
      * Move the startPoint or endPoint inside when it should be inside
@@ -138,6 +143,9 @@ private:
 public:
     /*!
      * Initializes the combing areas for every mesh in the layer (not support)
+     * 
+     * \warning \ref Comb::calc changes the order of polygons in \p Comb::comb_boundary_inside
+     * 
      * \param storage Where the layer polygon data is stored
      * \param layer_nr The number of the layer for which to generate the combing areas.
      * \param comb_boundary_inside The comb boundary within which to comb within layer parts.
@@ -146,12 +154,14 @@ public:
      * \param travel_avoid_distance The distance by which to avoid other layer parts when traveling through air.
      */
     Comb(SliceDataStorage& storage, int layer_nr, Polygons& comb_boundary_inside, int64_t offset_from_outlines, bool travel_avoid_other_parts, int64_t travel_avoid_distance);
-    
+
     ~Comb();
 
     /*!
      * Calculate the comb paths (if any) - one for each polygon combed alternated with travel paths
      * 
+     * \warning Changes the order of polygons in \ref Comb::comb_boundary_inside
+     * 
      * \param startPoint Where to start moving from
      * \param endPoint Where to move to
      * \param combPoints Output parameter: The points along the combing path, excluding the \p startPoint (?) and \p endPoint
@@ -160,7 +170,7 @@ public:
      * \param via_outside_makes_combing_fail When going through air is inavoidable, stop calculation early and return false.
      * \param fail_on_unavoidable_obstacles When moving over other parts is inavoidable, stop calculation early and return false.
      * \return Whether combing has succeeded; otherwise a retraction is needed.
-     */    
+     */
     bool calc(Point startPoint, Point endPoint, CombPaths& combPaths, bool startInside, bool endInside, int64_t max_comb_distance_ignored, bool via_outside_makes_combing_fail, bool fail_on_unavoidable_obstacles);
 };
 

src/pathPlanning/GCodePath.cpp

@@ -0,0 +1,24 @@
+//Copyright (C) 2016 Ultimaker
+//Released under terms of the AGPLv3 License
+
+#include "GCodePath.h"
+
+namespace cura
+{
+
+bool GCodePath::isTravelPath()
+{
+    return config->isTravelPath();
+}
+
+double GCodePath::getExtrusionMM3perMM()
+{
+    return flow * config->getExtrusionMM3perMM();
+}
+
+int GCodePath::getLineWidth()
+{
+    return flow * config->getLineWidth() * config->getFlowPercentage() / 100.0;
+}
+
+}

src/pathPlanning/GCodePath.h

@@ -0,0 +1,64 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+#ifndef PATH_PLANNING_G_CODE_PATH_H
+#define PATH_PLANNING_G_CODE_PATH_H
+
+#include "../SpaceFillType.h"
+#include "../GCodePathConfig.h"
+
+#include "TimeMaterialEstimates.h"
+
+namespace cura 
+{
+
+/*!
+ * A class for representing a planned path.
+ * 
+ * A path consists of several segments of the same type of movement: retracted travel, infill extrusion, etc.
+ * 
+ * This is a compact premature representation in which are line segments have the same config, i.e. the config of this path.
+ * 
+ * In the final representation (gcode) each line segment may have different properties, 
+ * which are added when the generated GCodePaths are processed.
+ */
+class GCodePath
+{
+public:
+    GCodePathConfig* config; //!< The configuration settings of the path.
+    SpaceFillType space_fill_type; //!< The type of space filling of which this path is a part
+    float flow; //!< A type-independent flow configuration (used for wall overlap compensation)
+    bool retract; //!< Whether the path is a move path preceded by a retraction move; whether the path is a retracted move path. 
+    bool perform_z_hop; //!< Whether to perform a z_hop in this path, which is assumed to be a travel path.
+    bool perform_prime; //!< Whether this path is preceded by a prime (poop)
+    std::vector<Point> points; //!< The points constituting this path.
+    bool done;//!< Path is finished, no more moves should be added, and a new path should be started instead of any appending done to this one.
+
+    bool spiralize; //!< Whether to gradually increment the z position during the printing of this path. A sequence of spiralized paths should start at the given layer height and end in one layer higher.
+
+    TimeMaterialEstimates estimates; //!< Naive time and material estimates
+
+    /*!
+     * Whether this config is the config of a travel path.
+     * 
+     * \return Whether this config is the config of a travel path.
+     */
+    bool isTravelPath();
+
+    /*!
+     * Get the material flow in mm^3 per mm traversed.
+     * 
+     * \warning Can only be called after the layer height has been set (which is done while writing the gcode!)
+     * 
+     * \return The flow
+     */
+    double getExtrusionMM3perMM();
+
+    /*!
+     * Get the actual line width (modulated by the flow)
+     * \return the actual line width as shown in layer view
+     */
+    int getLineWidth();
+};
+
+}//namespace cura
+
+#endif//PATH_PLANNING_G_CODE_PATH_H

src/pathPlanning/LinePolygonsCrossings.cpp

@@ -145,7 +145,7 @@ void LinePolygonsCrossings::getBasicCombingPath(CombPath& combPath)
 void LinePolygonsCrossings::getBasicCombingPath(PolyCrossings& polyCrossings, CombPath& combPath) 
 {
     PolygonRef poly = boundary[polyCrossings.poly_idx];
-    combPath.push_back(transformation_matrix.unapply(Point(polyCrossings.min.x - dist_to_move_boundary_point_outside, transformed_startPoint.Y)));
+    combPath.push_back(transformation_matrix.unapply(Point(polyCrossings.min.x - std::abs(dist_to_move_boundary_point_outside), transformed_startPoint.Y)));
     if ( ( polyCrossings.max.point_idx - polyCrossings.min.point_idx + poly.size() ) % poly.size() 
         < poly.size() / 2 )
     { // follow the path in the same direction as the winding order of the boundary polygon
@@ -166,7 +166,7 @@ void LinePolygonsCrossings::getBasicCombingPath(PolyCrossings& polyCrossings, Co
             combPath.push_back(PolygonUtils::getBoundaryPointWithOffset(poly, point_idx, dist_to_move_boundary_point_outside));
         }
     }
-    combPath.push_back(transformation_matrix.unapply(Point(polyCrossings.max.x + dist_to_move_boundary_point_outside, transformed_startPoint.Y))); 
+    combPath.push_back(transformation_matrix.unapply(Point(polyCrossings.max.x + std::abs(dist_to_move_boundary_point_outside), transformed_startPoint.Y)));
 }
 
 
@@ -194,9 +194,9 @@ bool LinePolygonsCrossings::optimizePath(CombPath& comb_path, CombPath& optimize
             continue;
         }
         Point& current_point = optimized_comb_path.back();
-        if (PolygonUtils::polygonCollidesWithlineSegment(boundary, current_point, comb_path[point_idx]))
+        if (PolygonUtils::polygonCollidesWithLineSegment(current_point, comb_path[point_idx], loc_to_line_grid))
         {
-            if (PolygonUtils::polygonCollidesWithlineSegment(boundary, current_point, comb_path[point_idx - 1]))
+            if (PolygonUtils::polygonCollidesWithLineSegment(current_point, comb_path[point_idx - 1], loc_to_line_grid))
             {
                 comb_path.cross_boundary = true;
             }
@@ -209,7 +209,7 @@ bool LinePolygonsCrossings::optimizePath(CombPath& comb_path, CombPath& optimize
             // TODO: add the below extra optimization? (+/- 7% extra computation time, +/- 2% faster print for Dual_extrusion_support_generation.stl)
             while (optimized_comb_path.size() > 1)
             {
-                if (PolygonUtils::polygonCollidesWithlineSegment(boundary, optimized_comb_path[optimized_comb_path.size() - 2], comb_path[point_idx]))
+                if (PolygonUtils::polygonCollidesWithLineSegment(optimized_comb_path[optimized_comb_path.size() - 2], comb_path[point_idx], loc_to_line_grid))
                 {
                     break;
                 }

src/pathPlanning/LinePolygonsCrossings.h

@@ -3,6 +3,8 @@
 #define PATH_PLANNING_LINE_POLYGONS_CROSSINGS_H
 
 #include "../utils/polygon.h"
+#include "../utils/polygonUtils.h"
+#include "../utils/SparseLineGrid.h"
 
 #include "CombPath.h"
 
@@ -80,6 +82,7 @@ private:
     unsigned int max_crossing_idx; //!< The index into LinePolygonsCrossings::crossings to the crossing with the maximal PolyCrossings::max crossing of all PolyCrossings's.
     
     Polygons& boundary; //!< The boundary not to cross during combing.
+    LocToLineGrid& loc_to_line_grid; //!< Mapping from locations to line segments of \ref LinePolygonsCrossings::boundary
     Point startPoint; //!< The start point of the scanline.
     Point endPoint; //!< The end point of the scanline.
     
@@ -163,8 +166,12 @@ private:
      * \param end the end point
      * \param dist_to_move_boundary_point_outside Distance used to move a point from a boundary so that it doesn't intersect with it anymore. (Precision issue)
      */
-    LinePolygonsCrossings(Polygons& boundary, Point& start, Point& end, int64_t dist_to_move_boundary_point_outside)
-    : boundary(boundary), startPoint(start), endPoint(end), dist_to_move_boundary_point_outside(dist_to_move_boundary_point_outside)
+    LinePolygonsCrossings(Polygons& boundary, LocToLineGrid& loc_to_line_grid, Point& start, Point& end, int64_t dist_to_move_boundary_point_outside)
+    : boundary(boundary)
+    , loc_to_line_grid(loc_to_line_grid)
+    , startPoint(start)
+    , endPoint(end)
+    , dist_to_move_boundary_point_outside(dist_to_move_boundary_point_outside)
     {
     }
     
@@ -173,15 +180,16 @@ public:
     /*!
      * The main function of this class: calculate one combing path within the boundary.
      * \param boundary The polygons to follow when calculating the basic combing path
+     * \param loc_to_line_grid A sparse grid mapping cells to all line segments of (at least) \p boundary in those cells
      * \param startPoint From where to start the combing move.
      * \param endPoint Where to end the combing move.
      * \param combPath Output parameter: the combing path generated.
      * \param fail_on_unavoidable_obstacles When moving over other parts is inavoidable, stop calculation early and return false.
      * \return Whether combing succeeded, i.e. we didn't cross any gaps/other parts
      */
-    static bool comb(Polygons& boundary, Point startPoint, Point endPoint, CombPath& combPath, int64_t dist_to_move_boundary_point_outside, int64_t max_comb_distance_ignored, bool fail_on_unavoidable_obstacles)
+    static bool comb(Polygons& boundary, LocToLineGrid& loc_to_line_grid, Point startPoint, Point endPoint, CombPath& combPath, int64_t dist_to_move_boundary_point_outside, int64_t max_comb_distance_ignored, bool fail_on_unavoidable_obstacles)
     {
-        LinePolygonsCrossings linePolygonsCrossings(boundary, startPoint, endPoint, dist_to_move_boundary_point_outside);
+        LinePolygonsCrossings linePolygonsCrossings(boundary, loc_to_line_grid, startPoint, endPoint, dist_to_move_boundary_point_outside);
         return linePolygonsCrossings.getCombingPath(combPath, max_comb_distance_ignored, fail_on_unavoidable_obstacles);
     };
 };

src/pathPlanning/NozzleTempInsert.cpp

@@ -0,0 +1,24 @@
+//Copyright (C) 2016 Ultimaker
+//Released under terms of the AGPLv3 License
+
+#include "NozzleTempInsert.h"
+
+namespace cura
+{
+
+NozzleTempInsert::NozzleTempInsert(unsigned int path_idx, int extruder, double temperature, bool wait, double time_after_path_start)
+: path_idx(path_idx)
+, time_after_path_start(time_after_path_start)
+, extruder(extruder)
+, temperature(temperature)
+, wait(wait)
+{
+    assert(temperature != 0 && temperature != -1 && "Temperature command must be set!");
+}
+
+void NozzleTempInsert::write(GCodeExport& gcode)
+{
+    gcode.writeTemperatureCommand(extruder, temperature, wait);
+}
+
+}

src/pathPlanning/NozzleTempInsert.h

@@ -0,0 +1,32 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+#ifndef PATH_PLANNING_NOZZLE_TEMP_INSERT_H
+#define PATH_PLANNING_NOZZLE_TEMP_INSERT_H
+
+#include "../gcodeExport.h"
+
+namespace cura 
+{
+
+/*!
+ * A gcode command to insert before a specific path.
+ * 
+ * Currently only used for preheat commands
+ */
+struct NozzleTempInsert
+{
+    const unsigned int path_idx; //!< The path before which to insert this command
+    double time_after_path_start; //!< The time after the start of the path, before which to insert the command // TODO: use this to insert command in between moves in a path!
+    int extruder; //!< The extruder for which to set the temp
+    double temperature; //!< The temperature of the temperature command to insert
+    bool wait; //!< Whether to wait for the temperature to be reached
+    NozzleTempInsert(unsigned int path_idx, int extruder, double temperature, bool wait, double time_after_path_start = 0.0);
+
+    /*!
+     * Write the temperature command at the current position in the gcode.
+     * \param gcode The actual gcode writer
+     */
+    void write(GCodeExport& gcode);
+};
+}//namespace cura
+
+#endif//PATH_PLANNING_NOZZLE_TEMP_INSERT_H

src/pathPlanning/TimeMaterialEstimates.cpp

@@ -0,0 +1,84 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+#include "TimeMaterialEstimates.h"
+
+namespace cura
+{
+
+TimeMaterialEstimates::TimeMaterialEstimates(double extrude_time, double unretracted_travel_time, double retracted_travel_time, double material)
+: extrude_time(extrude_time)
+, unretracted_travel_time(unretracted_travel_time)
+, retracted_travel_time(retracted_travel_time)
+, material(material)
+{
+}
+
+TimeMaterialEstimates::TimeMaterialEstimates()
+: extrude_time(0.0)
+, unretracted_travel_time(0.0)
+, retracted_travel_time(0.0)
+, material(0.0)
+{
+}
+
+TimeMaterialEstimates TimeMaterialEstimates::operator-(const TimeMaterialEstimates& other)
+{
+    return TimeMaterialEstimates(extrude_time - other.extrude_time,unretracted_travel_time - other.unretracted_travel_time,retracted_travel_time - other.retracted_travel_time,material - other.material);
+}
+
+TimeMaterialEstimates& TimeMaterialEstimates::operator-=(const TimeMaterialEstimates& other)
+{
+    extrude_time -= other.extrude_time;
+    unretracted_travel_time -= other.unretracted_travel_time;
+    retracted_travel_time -= other.retracted_travel_time;
+    material -= other.material;
+    return *this;
+}
+
+TimeMaterialEstimates TimeMaterialEstimates::operator+(const TimeMaterialEstimates& other)
+{
+    return TimeMaterialEstimates(extrude_time+other.extrude_time, unretracted_travel_time+other.unretracted_travel_time, retracted_travel_time+other.retracted_travel_time, material+other.material);
+}
+
+TimeMaterialEstimates& TimeMaterialEstimates::operator+=(const TimeMaterialEstimates& other)
+{
+    extrude_time += other.extrude_time;
+    unretracted_travel_time += other.unretracted_travel_time;
+    retracted_travel_time += other.retracted_travel_time;
+    material += other.material;
+    return *this;
+}
+
+double TimeMaterialEstimates::getExtrudeTime() const
+{
+    return extrude_time;
+}
+
+double TimeMaterialEstimates::getMaterial() const
+{
+    return material;
+}
+
+double TimeMaterialEstimates::getTotalTime() const
+{
+    return extrude_time + unretracted_travel_time + retracted_travel_time;
+}
+
+double TimeMaterialEstimates::getTotalUnretractedTime() const
+{
+    return extrude_time + unretracted_travel_time;
+}
+
+double TimeMaterialEstimates::getTravelTime() const
+{
+    return retracted_travel_time + unretracted_travel_time;
+}
+
+void TimeMaterialEstimates::reset()
+{
+    extrude_time = 0.0;
+    unretracted_travel_time = 0.0;
+    retracted_travel_time = 0.0;
+    material = 0.0;
+}
+
+}//namespace cura

src/pathPlanning/TimeMaterialEstimates.h

@@ -0,0 +1,124 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+#ifndef PATH_PLANNING_TIME_MATERIAL_ESTIMATES_H
+#define PATH_PLANNING_TIME_MATERIAL_ESTIMATES_H
+
+#include "../gcodeExport.h"
+
+namespace cura 
+{
+
+class ExtruderPlan; // forward declaration so that TimeMaterialEstimates can be a friend
+
+/*!
+ * Time and material estimates for a portion of paths, e.g. layer, extruder plan, path.
+ */
+class TimeMaterialEstimates
+{
+    friend class ExtruderPlan; // cause there the naive estimates are calculated
+private:
+    double extrude_time; //!< Time in seconds occupied by extrusion
+    double unretracted_travel_time; //!< Time in seconds occupied by non-retracted travel (non-extrusion)
+    double retracted_travel_time; //!< Time in seconds occupied by retracted travel (non-extrusion)
+    double material; //!< Material used (in mm^3)
+public:
+    /*!
+     * Basic contructor
+     * 
+     * \param extrude_time Time in seconds occupied by extrusion
+     * \param unretracted_travel_time Time in seconds occupied by non-retracted travel (non-extrusion)
+     * \param retracted_travel_time Time in seconds occupied by retracted travel (non-extrusion)
+     * \param material Material used (in mm^3)
+     */
+    TimeMaterialEstimates(double extrude_time, double unretracted_travel_time, double retracted_travel_time, double material);
+
+    /*!
+     * Basic constructor initializing all estimates to zero.
+     */
+    TimeMaterialEstimates();
+
+    /*!
+     * Set all estimates to zero.
+     */
+    void reset();
+
+    /*!
+     * Pointwise addition of estimate stats
+     * 
+     * \param other The estimates to add to these estimates.
+     * \return The resulting estimates
+     */
+    TimeMaterialEstimates operator+(const TimeMaterialEstimates& other);
+
+    /*!
+     * In place pointwise addition of estimate stats
+     * 
+     * \param other The estimates to add to these estimates.
+     * \return These estimates
+     */
+    TimeMaterialEstimates& operator+=(const TimeMaterialEstimates& other);
+
+    /*!
+     * \brief Subtracts the specified estimates from these estimates and returns
+     * the result.
+     * 
+     * Each of the estimates in this class are individually subtracted.
+     * 
+     * \param other The estimates to subtract from these estimates.
+     * \return These estimates with the specified estimates subtracted.
+     */
+    TimeMaterialEstimates operator-(const TimeMaterialEstimates& other);
+
+    /*!
+     * \brief Subtracts the specified elements from these estimates.
+     * 
+     * This causes the estimates in this instance to change. Each of the
+     * estimates in this class are individually subtracted.
+     * 
+     * \param other The estimates to subtract from these estimates.
+     * \return A reference to this instance.
+     */
+    TimeMaterialEstimates& operator-=(const TimeMaterialEstimates& other);
+
+    /*!
+     * Get total time estimate. The different time estimate member values added together.
+     * 
+     * \return the total of all different time estimate values 
+     */
+    double getTotalTime() const;
+
+    /*!
+     * Get the total time during which the head is not retracted.
+     * 
+     * This includes extrusion time and non-retracted travel time
+     * 
+     * \return the total time during which the head is not retracted.
+     */
+    double getTotalUnretractedTime() const;
+
+    /*!
+     * Get the total travel time.
+     * 
+     * This includes the retracted travel time as well as the unretracted travel time.
+     * 
+     * \return the total travel time.
+     */
+    double getTravelTime() const;
+
+    /*!
+     * Get the extrusion time.
+     * 
+     * \return extrusion time.
+     */
+    double getExtrudeTime() const;
+
+    /*!
+     * Get the amount of material used in mm^3.
+     * 
+     * \return amount of material
+     */
+    double getMaterial() const;
+};
+
+}//namespace cura
+
+#endif//PATH_PLANNING_TIME_MATERIAL_ESTIMATES_H

src/raft.cpp

@@ -43,7 +43,7 @@ int Raft::getZdiffBetweenRaftAndLayer1(const SliceDataStorage& storage)
     {
         return 0;
     }
-    const int64_t airgap = std::max(0, train.getSettingInMicrons("raft_airgap"));
+    const int64_t airgap = std::max((coord_t)0, train.getSettingInMicrons("raft_airgap"));
     const int64_t layer_0_overlap = storage.getSettingInMicrons("layer_0_z_overlap");
 
     const int64_t layer_height_0 = storage.getSettingInMicrons("layer_height_0");
@@ -75,6 +75,10 @@ int Raft::getFillerLayerHeight(const SliceDataStorage& storage)
 int Raft::getTotalExtraLayers(const SliceDataStorage& storage)
 {
     const ExtruderTrain& train = *storage.meshgroup->getExtruderTrain(storage.getSettingAsIndex("adhesion_extruder_nr"));
+    if (train.getSettingAsPlatformAdhesion("adhesion_type") != EPlatformAdhesion::RAFT)
+    {
+        return 0;
+    }
     return 2 + train.getSettingAsCount("raft_surface_layers") + getFillerLayerCount(storage);
 }
 

src/settings/SettingRegistry.cpp

@@ -125,6 +125,11 @@ bool SettingRegistry::getDefinitionFile(const std::string machine_id, std::strin
 
 int SettingRegistry::loadExtruderJSONsettings(unsigned int extruder_nr, SettingsBase* settings_base)
 {
+    if (extruder_train_ids.empty())
+    {
+        logError("Couldn't find any extruder trains!\n");
+        return -1;
+    }
     if (extruder_nr >= extruder_train_ids.size())
     {
         logWarning("Couldn't load extruder.def.json file for extruder %i. Index out of bounds.\n Loading first extruder definition instead.\n", extruder_nr);
@@ -220,8 +225,7 @@ int SettingRegistry::loadJSONsettingsFromDoc(rapidjson::Document& json_document,
 
     if (json_document.HasMember("settings"))
     {
-        std::list<std::string> path;
-        handleChildren(json_document["settings"], path, settings_base, warn_duplicates);
+        handleChildren(json_document["settings"], settings_base, warn_duplicates);
     }
     
     if (json_document.HasMember("overrides"))
@@ -243,7 +247,7 @@ int SettingRegistry::loadJSONsettingsFromDoc(rapidjson::Document& json_document,
     return 0;
 }
 
-void SettingRegistry::handleChildren(const rapidjson::Value& settings_list, std::list<std::string>& path, SettingsBase* settings_base, bool warn_duplicates)
+void SettingRegistry::handleChildren(const rapidjson::Value& settings_list, SettingsBase* settings_base, bool warn_duplicates)
 {
     if (!settings_list.IsObject())
     {
@@ -252,12 +256,10 @@ void SettingRegistry::handleChildren(const rapidjson::Value& settings_list, std:
     }
     for (rapidjson::Value::ConstMemberIterator setting_iterator = settings_list.MemberBegin(); setting_iterator != settings_list.MemberEnd(); ++setting_iterator)
     {
-        handleSetting(setting_iterator, path, settings_base, warn_duplicates);
+        handleSetting(setting_iterator, settings_base, warn_duplicates);
         if (setting_iterator->value.HasMember("children"))
         {
-            std::list<std::string> path_here = path;
-            path_here.push_back(setting_iterator->name.GetString());
-            handleChildren(setting_iterator->value["children"], path_here, settings_base, warn_duplicates);
+            handleChildren(setting_iterator->value["children"], settings_base, warn_duplicates);
         }
     }
 }
@@ -275,7 +277,7 @@ bool SettingRegistry::settingIsUsedByEngine(const rapidjson::Value& setting)
 }
 
 
-void SettingRegistry::handleSetting(const rapidjson::Value::ConstMemberIterator& json_setting_it, std::list<std::string>& path, SettingsBase* settings_base, bool warn_duplicates)
+void SettingRegistry::handleSetting(const rapidjson::Value::ConstMemberIterator& json_setting_it, SettingsBase* settings_base, bool warn_duplicates)
 {
     const rapidjson::Value& json_setting = json_setting_it->value;
     if (!json_setting.IsObject())

src/settings/SettingRegistry.h

@@ -174,17 +174,16 @@ private:
      * \param settings_base The settings base where to store the default values.
      * \param warn_duplicates whether to warn for duplicate setting definitions
      */
-    void handleChildren(const rapidjson::Value& settings_list, std::list<std::string>& path, SettingsBase* settings_base, bool warn_duplicates);
+    void handleChildren(const rapidjson::Value& settings_list, SettingsBase* settings_base, bool warn_duplicates);
     
     /*!
      * Handle a json object for a setting.
      * 
      * \param json_setting_it Iterator for the setting which contains the key (setting name) and attributes info
-     * \param path The path of (internal) setting names traversed to get to this object
      * \param settings_base The settings base where to store the default values.
      * \param warn_duplicates whether to warn for duplicate setting definitions
      */
-    void handleSetting(const rapidjson::Value::ConstMemberIterator& json_setting_it, std::list<std::string>& path, SettingsBase* settings_base, bool warn_duplicates);
+    void handleSetting(const rapidjson::Value::ConstMemberIterator& json_setting_it, SettingsBase* settings_base, bool warn_duplicates);
 };
 
 }//namespace cura

src/settings/settings.cpp

@@ -42,7 +42,7 @@ std::string toString(EGCodeFlavor flavor)
 }
 
 SettingsBaseVirtual::SettingsBaseVirtual()
-: parent(NULL)
+: parent(nullptr)
 {
 }
 
@@ -52,7 +52,7 @@ SettingsBaseVirtual::SettingsBaseVirtual(SettingsBaseVirtual* parent)
 }
 
 SettingsBase::SettingsBase()
-: SettingsBaseVirtual(NULL)
+: SettingsBaseVirtual(nullptr)
 {
 }
 
@@ -156,7 +156,7 @@ double SettingsBaseVirtual::getSettingInMillimeters(std::string key) const
     return atof(value.c_str());
 }
 
-int SettingsBaseVirtual::getSettingInMicrons(std::string key) const
+coord_t SettingsBaseVirtual::getSettingInMicrons(std::string key) const
 {
     return getSettingInMillimeters(key) * 1000.0;
 }
@@ -210,6 +210,12 @@ double SettingsBaseVirtual::getSettingInPercentage(std::string key) const
     return std::max(0.0, atof(value.c_str()));
 }
 
+double SettingsBaseVirtual::getSettingAsRatio(std::string key) const
+{
+    std::string value = getSettingString(key);
+    return atof(value.c_str()) / 100.0;
+}
+
 double SettingsBaseVirtual::getSettingInSeconds(std::string key) const
 {
     std::string value = getSettingString(key);
@@ -345,12 +351,16 @@ EFillMethod SettingsBaseVirtual::getSettingAsFillMethod(std::string key) const
         return EFillMethod::GRID;
     if (value == "cubic")
         return EFillMethod::CUBIC;
+    if (value == "cubicsubdiv")
+        return EFillMethod::CUBICSUBDIV;
     if (value == "tetrahedral")
         return EFillMethod::TETRAHEDRAL;
     if (value == "triangles")
         return EFillMethod::TRIANGLES;
     if (value == "concentric")
         return EFillMethod::CONCENTRIC;
+    if (value == "concentric_3d")
+        return EFillMethod::CONCENTRIC_3D;
     if (value == "zigzag")
         return EFillMethod::ZIG_ZAG;
     return EFillMethod::NONE;
@@ -363,6 +373,8 @@ EPlatformAdhesion SettingsBaseVirtual::getSettingAsPlatformAdhesion(std::string
         return EPlatformAdhesion::BRIM;
     if (value == "raft")
         return EPlatformAdhesion::RAFT;
+    if (value == "none")
+        return EPlatformAdhesion::NONE;
     return EPlatformAdhesion::SKIRT;
 }
 
@@ -400,6 +412,20 @@ ESurfaceMode SettingsBaseVirtual::getSettingAsSurfaceMode(std::string key) const
     return ESurfaceMode::NORMAL;
 }
 
+FillPerimeterGapMode SettingsBaseVirtual::getSettingAsFillPerimeterGapMode(std::string key) const
+{
+    std::string value = getSettingString(key);
+    if (value == "nowhere")
+    {
+        return FillPerimeterGapMode::NOWHERE;
+    }
+    if (value == "everywhere")
+    {
+        return FillPerimeterGapMode::EVERYWHERE;
+    }
+    return FillPerimeterGapMode::NOWHERE;
+}
+
 CombingMode SettingsBaseVirtual::getSettingAsCombingMode(std::string key)
 {
     std::string value = getSettingString(key);

src/settings/settings.h

@@ -105,9 +105,11 @@ enum class EFillMethod
     LINES,
     GRID,
     CUBIC,
+    CUBICSUBDIV,
     TETRAHEDRAL,
     TRIANGLES,
     CONCENTRIC,
+    CONCENTRIC_3D,
     ZIG_ZAG,
     NONE
 };
@@ -119,7 +121,8 @@ enum class EPlatformAdhesion
 {
     SKIRT,
     BRIM,
-    RAFT
+    RAFT,
+    NONE
 };
 
 /*!
@@ -146,6 +149,12 @@ enum class ESurfaceMode
     BOTH
 };
 
+enum class FillPerimeterGapMode
+{
+    NOWHERE,
+    EVERYWHERE
+};
+
 enum class CombingMode
 {
     OFF,
@@ -222,12 +231,13 @@ public:
     double getSettingInAngleDegrees(std::string key) const;
     double getSettingInAngleRadians(std::string key) const;
     double getSettingInMillimeters(std::string key) const;
-    int getSettingInMicrons(std::string key) const;
+    coord_t getSettingInMicrons(std::string key) const;
     bool getSettingBoolean(std::string key) const;
     double getSettingInDegreeCelsius(std::string key) const;
     double getSettingInMillimetersPerSecond(std::string key) const;
     double getSettingInCubicMillimeters(std::string key) const;
     double getSettingInPercentage(std::string key) const;
+    double getSettingAsRatio(std::string key) const; //!< For settings which are provided in percentage
     double getSettingInSeconds(std::string key) const;
 
     FlowTempGraph getSettingAsFlowTempGraph(std::string key) const;
@@ -240,6 +250,7 @@ public:
     ESupportType getSettingAsSupportType(std::string key) const;
     EZSeamType getSettingAsZSeamType(std::string key) const;
     ESurfaceMode getSettingAsSurfaceMode(std::string key) const;
+    FillPerimeterGapMode getSettingAsFillPerimeterGapMode(std::string key) const;
     CombingMode getSettingAsCombingMode(std::string key);
     SupportDistPriority getSettingAsSupportDistPriority(std::string key);
 };

src/skin.cpp

@@ -143,13 +143,23 @@ void generateInfill(int layerNr, SliceMeshStorage& mesh, const int innermost_wal
 {
     SliceLayer& layer = mesh.layers[layerNr];
 
+    int extra_offset = 0;
+    EFillMethod fill_pattern = mesh.getSettingAsFillMethod("infill_pattern");
+    if ((fill_pattern == EFillMethod::CONCENTRIC || fill_pattern == EFillMethod::CONCENTRIC_3D)
+        && mesh.getSettingBoolean("alternate_extra_perimeter")
+        && layerNr % 2 == 0
+        && mesh.getSettingInMicrons("infill_line_distance") > mesh.getSettingInMicrons("infill_line_width") * 2)
+    {
+        extra_offset = -innermost_wall_line_width;
+    }
+
     for(SliceLayerPart& part : layer.parts)
     {
         if (int(part.insets.size()) < wall_line_count)
         {
             continue; // the last wall is not present, the part should only get inter preimeter gaps, but no infill.
         }
-        Polygons infill = part.insets.back().offset(-innermost_wall_line_width / 2 - infill_skin_overlap);
+        Polygons infill = part.insets.back().offset(extra_offset - innermost_wall_line_width / 2 - infill_skin_overlap);
 
         for(SliceLayerPart& part2 : layer.parts)
         {
@@ -162,8 +172,17 @@ void generateInfill(int layerNr, SliceMeshStorage& mesh, const int innermost_wal
             }
         }
         infill.removeSmallAreas(MIN_AREA_SIZE);
-        
-        part.infill_area = infill.offset(infill_skin_overlap);
+
+        Polygons final_infill = infill.offset(infill_skin_overlap);
+
+        if (mesh.getSettingBoolean("infill_hollow"))
+        {
+            part.print_outline = part.print_outline.difference(final_infill);
+        }
+        else
+        {
+            part.infill_area = final_infill;
+        }
     }
 }
 

src/sliceDataStorage.cpp

@@ -1,6 +1,11 @@
+//Copyright (c) 2016 Ultimaker B.V.
+//CuraEngine is released under the terms of the AGPLv3 or higher.
+
 #include "sliceDataStorage.h"
 
 #include "FffProcessor.h" //To create a mesh group with if none is provided.
+#include "infill/SubDivCube.h" // For the destructor
+
 
 namespace cura
 {
@@ -67,6 +72,14 @@ void SliceLayer::getSecondOrInnermostWalls(Polygons& layer_walls) const
     }
 }
 
+SliceMeshStorage::~SliceMeshStorage()
+{
+    if (base_subdiv_cube)
+    {
+        delete base_subdiv_cube;
+    }
+}
+
 std::vector<RetractionConfig> SliceDataStorage::initializeRetractionConfigs()
 {
     std::vector<RetractionConfig> ret;
@@ -96,6 +109,7 @@ std::vector<GCodePathConfig> SliceDataStorage::initializeSkirtBrimConfigs()
 
 SliceDataStorage::SliceDataStorage(MeshGroup* meshgroup) : SettingsMessenger(meshgroup),
     meshgroup(meshgroup != nullptr ? meshgroup : new MeshGroup(FffProcessor::getInstance())), //If no mesh group is provided, we roll our own.
+    print_layer_count(0),
     retraction_config_per_extruder(initializeRetractionConfigs()),
     extruder_switch_retraction_config_per_extruder(initializeRetractionConfigs()),
     travel_config_per_extruder(initializeTravelConfigs()),
@@ -105,7 +119,8 @@ SliceDataStorage::SliceDataStorage(MeshGroup* meshgroup) : SettingsMessenger(mes
     raft_surface_config(PrintFeatureType::SupportInterface),
     support_config(PrintFeatureType::Support),
     support_skin_config(PrintFeatureType::SupportInterface),
-    max_object_height_second_to_last_extruder(-1)
+    max_print_height_second_to_last_extruder(-1),
+    primeTower(*this)
 {
 }
 
@@ -142,7 +157,7 @@ Polygons SliceDataStorage::getLayerOutlines(int layer_nr, bool include_helper_pa
         {
             for (const SliceMeshStorage& mesh : meshes)
             {
-                if (mesh.getSettingBoolean("infill_mesh"))
+                if (mesh.getSettingBoolean("infill_mesh") || mesh.getSettingBoolean("anti_overhang_mesh"))
                 {
                     continue;
                 }
@@ -161,7 +176,10 @@ Polygons SliceDataStorage::getLayerOutlines(int layer_nr, bool include_helper_pa
                 total.add(support.supportLayers[std::max(0, layer_nr)].supportAreas);
                 total.add(support.supportLayers[std::max(0, layer_nr)].skin);
             }
-            total.add(primeTower.ground_poly);
+            if (primeTower.enabled)
+            {
+                total.add(primeTower.ground_poly);
+            }
         }
         return total;
     }
@@ -202,27 +220,33 @@ Polygons SliceDataStorage::getLayerSecondOrInnermostWalls(int layer_nr, bool inc
                 total.add(support.supportLayers[std::max(0, layer_nr)].supportAreas);
                 total.add(support.supportLayers[std::max(0, layer_nr)].skin);
             }
-            total.add(primeTower.ground_poly);
+            if (primeTower.enabled)
+            {
+                total.add(primeTower.ground_poly);
+            }
         }
         return total;
     }
 
 }
 
-std::vector< bool > SliceDataStorage::getExtrudersUsed()
+std::vector<bool> SliceDataStorage::getExtrudersUsed() const
 {
 
     std::vector<bool> ret;
     ret.resize(meshgroup->getExtruderCount(), false);
 
-    ret[getSettingAsIndex("adhesion_extruder_nr")] = true; 
-    { // process brim/skirt
-        for (int extr_nr = 0; extr_nr < meshgroup->getExtruderCount(); extr_nr++)
-        {
-            if (skirt_brim[extr_nr].size() > 0)
+    if (getSettingAsPlatformAdhesion("adhesion_type") != EPlatformAdhesion::NONE)
+    {
+        ret[getSettingAsIndex("adhesion_extruder_nr")] = true;
+        { // process brim/skirt
+            for (int extr_nr = 0; extr_nr < meshgroup->getExtruderCount(); extr_nr++)
             {
-                ret[extr_nr] = true;
-                continue;
+                if (skirt_brim[extr_nr].size() > 0)
+                {
+                    ret[extr_nr] = true;
+                    continue;
+                }
             }
         }
     }
@@ -236,9 +260,103 @@ std::vector< bool > SliceDataStorage::getExtrudersUsed()
     ret[getSettingAsIndex("support_interface_extruder_nr")] = true;
 
     // all meshes are presupposed to actually have content
-    for (SliceMeshStorage& mesh : meshes)
+    for (const SliceMeshStorage& mesh : meshes)
     {
-        ret[mesh.getSettingAsIndex("extruder_nr")] = true;
+        if (!mesh.getSettingBoolean("anti_overhang_mesh")
+            && !mesh.getSettingBoolean("support_mesh")
+        )
+        {
+            ret[mesh.getSettingAsIndex("extruder_nr")] = true;
+        }
+    }
+    return ret;
+}
+
+std::vector<bool> SliceDataStorage::getExtrudersUsed(int layer_nr) const
+{
+
+    std::vector<bool> ret;
+    ret.resize(meshgroup->getExtruderCount(), false);
+
+    bool include_adhesion = true;
+    bool include_helper_parts = true;
+    bool include_models = true;
+    if (layer_nr < 0)
+    {
+        include_models = false;
+        if (layer_nr < -Raft::getFillerLayerCount(*this))
+        {
+            include_helper_parts = false;
+        }
+        else
+        {
+            layer_nr = 0; // because the helper parts are copied from the initial layer in the filler layer
+            include_adhesion = false;
+        }
+    }
+    else if (layer_nr > 0 || getSettingAsPlatformAdhesion("adhesion_type") == EPlatformAdhesion::RAFT)
+    { // only include adhesion only for layers where platform adhesion actually occurs
+        // i.e. layers < 0 are for raft, layer 0 is for brim/skirt
+        include_adhesion = false;
+    }
+    if (include_adhesion)
+    {
+        ret[getSettingAsIndex("adhesion_extruder_nr")] = true;
+        { // process brim/skirt
+            for (int extr_nr = 0; extr_nr < meshgroup->getExtruderCount(); extr_nr++)
+            {
+                if (skirt_brim[extr_nr].size() > 0)
+                {
+                    ret[extr_nr] = true;
+                    continue;
+                }
+            }
+        }
+    }
+
+    // TODO: ooze shield, draft shield ..?
+
+    if (include_helper_parts)
+    {
+        // support
+        if (layer_nr < int(support.supportLayers.size()))
+        {
+            const SupportLayer& support_layer = support.supportLayers[layer_nr];
+            if (layer_nr == 0)
+            {
+                if (support_layer.supportAreas.size() > 0)
+                {
+                    ret[getSettingAsIndex("support_extruder_nr_layer_0")] = true;
+                }
+            }
+            else
+            {
+                if (support_layer.supportAreas.size() > 0)
+                {
+                    ret[getSettingAsIndex("support_infill_extruder_nr")] = true;
+                }
+            }
+            if (support_layer.skin.size() > 0)
+            {
+                ret[getSettingAsIndex("support_interface_extruder_nr")] = true;
+            }
+        }
+    }
+
+    if (include_models)
+    {
+        for (const SliceMeshStorage& mesh : meshes)
+        {
+            if (layer_nr >= int(mesh.layers.size()))
+            {
+                continue;
+            }
+            const SliceLayer& layer = mesh.layers[layer_nr];
+            if (layer.parts.size() > 0)
+            {
+                ret[mesh.getSettingAsIndex("extruder_nr")] = true;
+            }
+        }
     }
     return ret;
 }

src/sliceDataStorage.h

@@ -125,6 +125,8 @@ class SupportLayer
 public:
     Polygons supportAreas; //!< normal support areas
     Polygons skin; //!< the support areas which are to be printed as denser roofs and/or bottoms. Note that the roof/bottom areas and support areas should be mutually exclusive.
+    Polygons support_mesh; //!< Areas from support meshes
+    Polygons anti_overhang; //!< Areas where no overhang should be detected.
 };
 
 class SupportStorage
@@ -141,6 +143,8 @@ public:
 };
 /******************/
 
+class SubDivCube; // forward declaration to prevent dependency loop
+
 class SliceMeshStorage : public SettingsMessenger // passes on settings from a Mesh object
 {
 public:
@@ -153,18 +157,23 @@ public:
     GCodePathConfig skin_config;
     std::vector<GCodePathConfig> infill_config;
 
+    SubDivCube* base_subdiv_cube;
+
     SliceMeshStorage(SettingsBaseVirtual* settings, unsigned int slice_layer_count)
     : SettingsMessenger(settings)
     , layer_nr_max_filled_layer(0)
     , inset0_config(PrintFeatureType::OuterWall)
     , insetX_config(PrintFeatureType::InnerWall)
     , skin_config(PrintFeatureType::Skin)
+    , base_subdiv_cube(nullptr)
     {
-        layers.reserve(slice_layer_count);
+        layers.resize(slice_layer_count);
         infill_config.reserve(MAX_INFILL_COMBINE);
         for(int n=0; n<MAX_INFILL_COMBINE; n++)
             infill_config.emplace_back(PrintFeatureType::Infill);
     }
+
+    virtual ~SliceMeshStorage();
 };
 
 class SliceDataStorage : public SettingsMessenger, NoCopy
@@ -172,6 +181,8 @@ class SliceDataStorage : public SettingsMessenger, NoCopy
 public:
     MeshGroup* meshgroup; // needed to pass on the per extruder settings.. (TODO: put this somewhere else? Put the per object settings here directly, or a pointer only to the per object settings.)
 
+    unsigned int print_layer_count; //!< The total number of layers (except the raft and filler layers)
+
     Point3 model_size, model_min, model_max;
     std::vector<SliceMeshStorage> meshes;
 
@@ -195,7 +206,10 @@ public:
     Polygons skirt_brim[MAX_EXTRUDERS]; //!< Skirt and brim polygons per extruder, ordered from inner to outer polygons.
     Polygons raftOutline;               //Storage for the outline of the raft. Will be filled with lines when the GCode is generated.
 
-    int max_object_height_second_to_last_extruder; //!< Used in multi-extrusion: the layer number beyond which all models are printed with the same extruder
+    int max_print_height_second_to_last_extruder; //!< Used in multi-extrusion: the layer number beyond which all models are printed with the same extruder
+    std::vector<int> max_print_height_per_extruder; //!< For each extruder the highest layer number at which it is used.
+    std::vector<size_t> max_print_height_order; //!< Ordered indices into max_print_height_per_extruder: back() will return the extruder number with the highest print height.
+
     PrimeTower primeTower;
 
     std::vector<Polygons> oozeShield;        //oozeShield per layer
@@ -256,7 +270,15 @@ public:
      * 
      * \return a vector of bools indicating whether the extruder with corresponding index is used in this layer.
      */
-    std::vector<bool> getExtrudersUsed();
+    std::vector<bool> getExtrudersUsed() const;
+
+    /*!
+     * Get the extruders used on a particular layer.
+     * 
+     * \param layer_nr the layer for which to check
+     * \return a vector of bools indicating whether the extruder with corresponding index is used in this layer.
+     */
+    std::vector<bool> getExtrudersUsed(int layer_nr) const;
 };
 
 }//namespace cura

src/slicer.cpp

@@ -759,7 +759,7 @@ void SlicerLayer::makePolygons(const Mesh* mesh, bool keep_none_closed, bool ext
         for (PolygonRef polyline : open_polylines)
         {
             if (polyline.size() > 0)
-                openPolylines.add(polyline);
+                polygons.add(polyline);
         }
     }
 

src/support.cpp

@@ -1,4 +1,7 @@
-/** Copyright (C) 2013 David Braam - Released under terms of the AGPLv3 License */
+//Copyright (C) 2013 David Braam
+//Copyright (c) 2016 Ultimaker B.V.
+//CuraEngine is released under the terms of the AGPLv3 or higher.
+
 #include <cmath> // sqrt
 #include <utility> // pair
 #include <deque>
@@ -65,14 +68,32 @@ Polygons AreaSupport::join(Polygons& supportLayer_up, Polygons& supportLayer_thi
 
 void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int layer_count)
 {
+    int max_layer_nr_support_mesh_filled;
+    for (max_layer_nr_support_mesh_filled = storage.support.supportLayers.size() - 1; max_layer_nr_support_mesh_filled >= 0; max_layer_nr_support_mesh_filled--)
+    {
+        const SupportLayer& support_layer = storage.support.supportLayers[max_layer_nr_support_mesh_filled];
+        if (support_layer.supportAreas.size() > 0)
+        {
+            break;
+        }
+    }
+    storage.support.layer_nr_max_filled_layer = std::max(storage.support.layer_nr_max_filled_layer, max_layer_nr_support_mesh_filled);
+    for (int layer_nr = 0; layer_nr < max_layer_nr_support_mesh_filled; layer_nr++)
+    {
+        SupportLayer& support_layer = storage.support.supportLayers[max_layer_nr_support_mesh_filled];
+        support_layer.support_mesh = support_layer.support_mesh.unionPolygons();
+    }
+
     // initialization of supportAreasPerLayer
-    for (unsigned int layer_idx = 0; layer_idx < layer_count ; layer_idx++)
-        storage.support.supportLayers.emplace_back();
-    
-    for(unsigned int mesh_idx = 0; mesh_idx < storage.meshes.size(); mesh_idx++)
+    if (layer_count > storage.support.supportLayers.size())
+    { // there might alsready be anti_overhang_area data in the supportLayers
+        storage.support.supportLayers.resize(layer_count);
+    }
+
+    for (unsigned int mesh_idx = 0; mesh_idx < storage.meshes.size(); mesh_idx++)
     {
         SliceMeshStorage& mesh = storage.meshes[mesh_idx];
-        if (mesh.getSettingBoolean("infill_mesh"))
+        if (mesh.getSettingBoolean("infill_mesh") || mesh.getSettingBoolean("anti_overhang_mesh"))
         {
             continue;
         }
@@ -212,7 +233,6 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
         basic_and_full_overhang_above.push_front(computeBasicAndFullOverhang(storage, mesh, layer_idx, max_dist_from_lower_layer));
     }
 
-    bool still_in_upper_empty_layers = true;
     int overhang_points_pos = overhang_points.size() - 1;
     Polygons supportLayer_last;
     std::vector<Polygons> towerRoofs;
@@ -247,8 +267,9 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
         { // join with support from layer up                
             supportLayer_this = AreaSupport::join(supportLayer_last, supportLayer_this, join_distance, smoothing_distance, max_smoothing_angle, conical_support, conical_support_offset, conical_smallest_breadth);
         }
-        
-        
+
+        supportLayer_this = supportLayer_this.unionPolygons(storage.support.supportLayers[layer_idx].support_mesh);
+
         // move up from model
         if (layerZdistanceBottom > 0 && layer_idx >= layerZdistanceBottom)
         {
@@ -256,8 +277,8 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
             int bottomLayer = ((layer_idx - layerZdistanceBottom) / stepHeight) * stepHeight;
             supportLayer_this = supportLayer_this.difference(storage.getLayerOutlines(bottomLayer, false));
         }
-        
-        
+
+
         supportLayer_last = supportLayer_this;
         
         
@@ -277,18 +298,12 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
             }
             else
             {
-                supportLayer_this = supportLayer_this.difference(storage.getLayerOutlines(layer_idx, false).offset(supportXYDistance));
+                supportLayer_this = supportLayer_this.difference(outlines.offset(supportXYDistance));
             }
         }
 
         supportAreas[layer_idx] = supportLayer_this;
 
-        if (still_in_upper_empty_layers && supportLayer_this.size() > 0)
-        {
-            storage.support.layer_nr_max_filled_layer = std::max(storage.support.layer_nr_max_filled_layer, (int)layer_idx);
-            still_in_upper_empty_layers = false;
-        }
-        
         Progress::messageProgress(Progress::Stage::SUPPORT, storage.meshes.size() * mesh_idx + support_layer_count - layer_idx, support_layer_count * storage.meshes.size());
     }
     
@@ -326,6 +341,28 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
         }
     }
 
+    //Enforce top Z distance.
+    if (layerZdistanceTop > 0)
+    {
+        // this is performed after the main support generation loop above, because it affects the joining of polygons
+        // if this would be performed in the main loop then some support would not have been generated under the overhangs and consequently no support is generated for that,
+        // meaning almost no support would be generated in some cases which definitely need support.
+        for (size_t layer_idx = 0; layer_idx < storage.support.supportLayers.size() && layer_idx < support_layer_count - layerZdistanceTop; layer_idx++)
+        {
+            supportAreas[layer_idx] = supportAreas[layer_idx].difference(storage.getLayerOutlines(layer_idx + layerZdistanceTop, false));
+        }
+    }
+
+    for (unsigned int layer_idx = supportAreas.size() - 1; layer_idx != (unsigned int) std::max(-1, storage.support.layer_nr_max_filled_layer) ; layer_idx--)
+    {
+        const Polygons& support_here = supportAreas[layer_idx];
+        if (support_here.size() > 0)
+        {
+            storage.support.layer_nr_max_filled_layer = layer_idx;
+            break;
+        }
+    }
+
     storage.support.generated = true;
 }
 
@@ -349,6 +386,12 @@ std::pair<Polygons, Polygons> AreaSupport::computeBasicAndFullOverhang(const Sli
     Polygons supportLayer_supported =  supportLayer_supporter.offset(max_dist_from_lower_layer);
     Polygons basic_overhang = supportLayer_supportee.difference(supportLayer_supported);
 
+    const SupportLayer& support_layer = storage.support.supportLayers[layer_idx];
+    if (support_layer.anti_overhang.size())
+    {
+        basic_overhang = basic_overhang.difference(support_layer.anti_overhang);
+    }
+
 //     Polygons support_extension = basic_overhang.offset(max_dist_from_lower_layer);
 //     support_extension = support_extension.intersection(supportLayer_supported);
 //     support_extension = support_extension.intersection(supportLayer_supportee);
@@ -388,12 +431,17 @@ void AreaSupport::detectOverhangPoints(
                 
                 if (part_poly.size() > 0)
                 {
+                    Polygons part_poly_recomputed = part_poly.difference(storage.support.supportLayers[layer_idx].anti_overhang);
+                    if (part_poly_recomputed.size() == 0)
+                    {
+                        continue;
+                    }
                     if (overhang_points.size() > 0 && overhang_points.back().first == layer_idx)
-                        overhang_points.back().second.push_back(part_poly);
+                        overhang_points.back().second.push_back(part_poly_recomputed);
                     else 
                     {
                         std::vector<Polygons> small_part_polys;
-                        small_part_polys.push_back(part_poly);
+                        small_part_polys.push_back(part_poly_recomputed);
                         overhang_points.emplace_back<std::pair<int, std::vector<Polygons>>>(std::make_pair(layer_idx, small_part_polys));
                     }
                 }
@@ -444,15 +492,21 @@ void AreaSupport::handleTowers(
     }
     
     // make tower roofs
-    //for (Polygons& tower_roof : towerRoofs)
-    for (unsigned int r = 0; r < towerRoofs.size(); r++)
+    for (unsigned int roof_idx = 0; roof_idx < towerRoofs.size(); roof_idx++)
     {
-        supportLayer_this = supportLayer_this.unionPolygons(towerRoofs[r]);
-        
-        Polygons& tower_roof = towerRoofs[r];
-        if (tower_roof.size() > 0 && tower_roof[0].area() < supportTowerDiameter * supportTowerDiameter)
+        Polygons& tower_roof = towerRoofs[roof_idx];
+        if (tower_roof.size() > 0)
         {
-            towerRoofs[r] = tower_roof.offset(towerRoofExpansionDistance);
+            supportLayer_this = supportLayer_this.unionPolygons(tower_roof);
+
+            if (tower_roof[0].area() < supportTowerDiameter * supportTowerDiameter)
+            {
+                tower_roof = tower_roof.offset(towerRoofExpansionDistance);
+            }
+            else
+            {
+                tower_roof.clear();
+            }
         }
     }
 }

src/support.h

@@ -17,7 +17,6 @@ public:
      * \param layer_count total number of layers
      */
     static void generateSupportAreas(SliceDataStorage& storage, unsigned int layer_count);
-        
 private:
     /*!
      * Generate support polygons over all layers for one object.

src/timeEstimate.h

@@ -57,7 +57,7 @@ public:
     };
 
 private:
-    double max_feedrate[NUM_AXIS] = {600, 600, 40, 25};
+    double max_feedrate[NUM_AXIS] = {600, 600, 40, 25}; // mm/s
     double minimumfeedrate = 0.01;
     double acceleration = 3000;
     double max_acceleration[NUM_AXIS] = {9000, 9000, 100, 10000};

src/utils/AABB3D.cpp

@@ -15,8 +15,8 @@ AABB3D::AABB3D()
 
 bool AABB3D::hit(const AABB3D& other) const
 {
-    if (   max.x < other.min.y
-        || min.x > other.max.y
+    if (   max.x < other.min.x
+        || min.x > other.max.x
         || max.y < other.min.y
         || min.y > other.max.y
         || max.z < other.min.z
@@ -37,6 +37,12 @@ void AABB3D::include(Point3 p)
     max.z = std::max(max.z, p.z);   
 }
 
+void AABB3D::includeZ(int32_t z)
+{
+    min.z = std::min(min.z, z);
+    max.z = std::max(max.z, z);
+}
+
 void AABB3D::offset(Point3 offset)
 {
     min += offset;

src/utils/AABB3D.h

@@ -38,6 +38,14 @@ struct AABB3D
      */
     void include(Point3 p);
 
+    /*!
+     * Expand the AABB3D to include a z-coordinate.
+     *
+     * This is for including a point of which the X and Y coordinates are
+     * unknown but known to already be included in the bounding box.
+     */
+    void includeZ(int32_t z);
+
     /*!
      * Offset the coordinates of the bounding box.
      * \param offset The offset with which to offset the AABB3D.

src/utils/LazyInitialization.h

@@ -0,0 +1,129 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+#ifndef UTILS_LAZY_INITIALIZATION_H
+#define UTILS_LAZY_INITIALIZATION_H
+
+#include <functional> // bind, function
+
+#include "optional.h"
+
+namespace cura
+{
+
+/*!
+ * Class for initializing an object only when it's requested
+ * 
+ * Credits to Johannes Goller
+ * 
+ * \tparam T The type of the object to instantiate lazily
+ * \tparam Args The types of the arguments to the constructor or constructor function object
+ */
+template <typename T, typename... Args>
+class LazyInitialization : public std::optional<T>
+{
+public:
+
+    /*!
+     * Delayed constructor call of T class
+     * 
+     * \warning passing references or pointers as parameters means these objects will be given to the constructor at evaluation time.
+     * Make sure these references/pointers are not invalidated between construction of the lazy object and the evaluation.
+     */
+    LazyInitialization(Args... args)
+    : std::optional<T>()
+    , constructor(
+            [args...]()
+            {
+                return new T(args...);
+            }
+        )
+    { }
+
+    /*!
+     * Delayed function call for creating a T object
+     * 
+     * Performs a copy from the return value of the function on the stack to the heap.
+     * 
+     * \warning passing references or pointers as parameters means these objects will be given to the function object at evaluation time.
+     * Make sure these references/pointers are not invalidated between construction of the lazy object and the evaluation.
+     */
+    LazyInitialization(const std::function<T (Args...)>& f, Args... args)
+    : std::optional<T>()
+    , constructor(
+            [f, args...]()
+            {
+                return new T(f(args...));
+            }
+        )
+    { }
+
+    /*!
+     * Delayed function call for creating a T object
+     * 
+     * \warning passing references or pointers as parameters means these objects will be given to the function object at evaluation time.
+     * Make sure these references/pointers are not invalidated between construction of the lazy object and the evaluation.
+     */
+    LazyInitialization(const std::function<T* (Args...)>& f, Args... args)
+    : std::optional<T>()
+    , constructor(
+            [f, args...]()
+            {
+                return f(args...);
+            }
+        )
+    {
+    }
+
+    LazyInitialization(LazyInitialization<T, Args...>& other) //!< copy constructor
+    : std::optional<T>(other)
+    , constructor(other.constructor)
+    {
+    }
+
+    LazyInitialization(LazyInitialization<T, Args...>&& other) //!< move constructor
+    : std::optional<T>(other)
+    {
+        constructor = std::move(other.constructor);
+    }
+
+    /*!
+     * Dereference this lazy object
+     * 
+     * Calls constructor if object isn't constructed yet.
+     */
+    T& operator*()
+    {
+        if (!std::optional<T>::instance)
+        {
+            std::optional<T>::instance = constructor();
+        }
+        return std::optional<T>::operator*();
+    }
+
+    T* operator->() const
+    {
+        if (!std::optional<T>::instance)
+        {
+            std::optional<T>::instance = constructor();
+        }
+        return std::optional<T>::operator->();
+    }
+
+    LazyInitialization<T, Args...>& operator=(LazyInitialization<T, Args...>&& other)
+    {
+        std::optional<T>::operator=(other);
+        constructor = other.constructor;
+        return *this;
+    }
+
+    void swap(LazyInitialization<T, Args...>& other)
+    {
+        std::optional<T>::swap(other);
+        std::swap(constructor, other.constructor);
+    }
+
+private:
+    std::function<T* ()> constructor;
+};
+
+}//namespace cura
+#endif // UTILS_LAZY_INITIALIZATION_H

src/utils/LinearAlg2D.cpp

@@ -2,6 +2,8 @@
 #include "linearAlg2D.h"
 
 #include <cmath> // atan2
+#include <cassert>
+#include <algorithm> // swap
 
 #include "intpoint.h" // dot
 
@@ -108,4 +110,38 @@ bool LinearAlg2D::getPointOnLineWithDist(const Point p, const Point a, const Poi
     }
 }
 
+bool LinearAlg2D::lineSegmentsCollide(Point a_from_transformed, Point a_to_transformed, Point b_from_transformed, Point b_to_transformed)
+{
+    assert(std::abs(a_from_transformed.Y - a_to_transformed.Y) < 2 && "line a is supposed to be transformed to be aligned with the X axis!");
+    assert(a_from_transformed.X - 2 <= a_to_transformed.X && "line a is supposed to be aligned with X axis in positive direction!");
+    if ((b_from_transformed.Y >= a_from_transformed.Y && b_to_transformed.Y <= a_from_transformed.Y) || (b_to_transformed.Y >= a_from_transformed.Y && b_from_transformed.Y <= a_from_transformed.Y))
+    {
+        if(b_to_transformed.Y == b_from_transformed.Y)
+        {
+            if (b_to_transformed.X < b_from_transformed.X)
+            {
+                std::swap(b_to_transformed.X, b_from_transformed.X);
+            }
+            if (b_from_transformed.X > a_to_transformed.X)
+            {
+                return false;
+            }
+            if (b_to_transformed.X < a_from_transformed.X)
+            {
+                return false;
+            }
+            return true;
+        }
+        else
+        {
+            int64_t x = b_from_transformed.X + (b_to_transformed.X - b_from_transformed.X) * (a_from_transformed.Y - b_from_transformed.Y) / (b_to_transformed.Y - b_from_transformed.Y);
+            if (x >= a_from_transformed.X && x <= a_to_transformed.X)
+            {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
 } // namespace cura

src/utils/ListPolyIt.h

@@ -49,10 +49,11 @@ public:
     {
         return !(*this == other);
     }
-    void operator=(const ListPolyIt& other)
+    ListPolyIt& operator=(const ListPolyIt& other)
     {
         poly = other.poly;
         it = other.it;
+        return *this;
     }
     //! move the iterator forward (and wrap around at the end)
     ListPolyIt& operator++() 

src/utils/PolygonProximityLinker.cpp

@@ -112,9 +112,10 @@ void PolygonProximityLinker::findProximatePoints()
                 //  o--->o-->o-->o->
                 //  2    4   6   8
                 std::unordered_set<ListPolyIt> nearby_lines;
-                auto process_func = [&nearby_lines](const ListPolyIt& elem)
+                std::function<bool (const ListPolyIt&)> process_func = [&nearby_lines](const ListPolyIt& elem)
                 {
                     nearby_lines.emplace(elem);
+                    return true;
                 };
                 line_grid.processNearby(point_it.p(), proximity_distance, process_func);
                 for (const ListPolyIt& nearby_line : nearby_lines)
@@ -139,9 +140,10 @@ void PolygonProximityLinker::findProximatePoints()
         //  o--->o-->o-->o->
         //  2    4   6   8
         std::unordered_set<ListPolyIt> nearby_vert_its;
-        auto process_func = [&nearby_vert_its](const ListPolyIt& elem)
+        std::function<bool (const ListPolyIt&)> process_func = [&nearby_vert_its](const ListPolyIt& elem)
         {
             nearby_vert_its.emplace(elem);
+            return true;
         };
         line_grid.processNearby(new_point_it.p(), proximity_distance, process_func);
         // because we use the same line_grid as before the resulting nearby_points

src/utils/PolygonsPointIndex.h

@@ -43,6 +43,13 @@ public:
         }
         return (*polygons)[poly_idx][point_idx];
     }
+    /*!
+     * Get the polygon to which this PolygonsPointIndex refers
+     */
+    const PolygonRef getPolygon() const
+    {
+        return (*polygons)[poly_idx];
+    }
     /*!
      * Test whether two iterators refer to the same polygon in the same polygon list.
      * 
@@ -57,11 +64,12 @@ public:
     {
         return !(*this == other);
     }
-    void operator=(const PolygonsPointIndex& other)
+    PolygonsPointIndex& operator=(const PolygonsPointIndex& other)
     {
         polygons = other.polygons;
         poly_idx = other.poly_idx;
         point_idx = other.point_idx;
+        return *this;
     }
     //! move the iterator forward (and wrap around at the end)
     PolygonsPointIndex& operator++() 

src/utils/SparseGrid.h

@@ -8,6 +8,7 @@
 #include <cassert>
 #include <unordered_map>
 #include <vector>
+#include <functional>
 
 namespace cura {
 
@@ -75,11 +76,22 @@ public:
      * \param[in] query_pt The point to search around.
      * \param[in] radius The search radius.
      * \param[in] process_func Processes each element.  process_func(elem) is
-     *    called for each element in the cell.
+     *    called for each element in the cell. Processing stops if function returns false.
      */
-    template<class ProcessFunc>
     void processNearby(const Point &query_pt, coord_t radius,
-                       ProcessFunc &process_func) const;
+                       const std::function<bool (const ElemT&)>& process_func) const;
+
+    /*! \brief Process elements from cells that might contain sought after points along a line.
+     *
+     * Processes elements from cells that cross the line \p query_line.
+     * May process elements that are up to sqrt(2) * cell_size from \p query_line.
+     *
+     * \param[in] query_line The line along which to check each cell
+     * \param[in] process_func Processes each element.  process_func(elem) is
+     *    called for each element in the cells. Processing stops if function returns false.
+     */
+    void processLine(const std::pair<Point, Point> query_line,
+                       const std::function<bool (const Elem&)>& process_elem_func) const;
 
     coord_t getCellSize() const;
 
@@ -92,11 +104,29 @@ protected:
      *
      * \param[in] grid_pt The grid coordinates of the cell.
      * \param[in] process_func Processes each element.  process_func(elem) is
-     *    called for each element in the cell.
+     *    called for each element in the cell. Processing stops if function returns false.
+     * \return Whether we need to continue processing a next cell.
      */
-    template<class ProcessFunc>
-    void processFromCell(const GridPoint &grid_pt,
-                         ProcessFunc &process_func) const;
+    bool processFromCell(const GridPoint &grid_pt,
+                         const std::function<bool (const Elem&)>& process_func) const;
+
+    /*! \brief Process cells along a line indicated by \p line.
+     *
+     * \param[in] line The line along which to process cells
+     * \param[in] process_func Processes each cell.  process_func(elem) is
+     *    called for each cell. Processing stops if function returns false.
+     */
+    void processLineCells(const std::pair<Point, Point> line,
+                         const std::function<bool (GridPoint)>& process_cell_func);
+
+    /*! \brief Process cells along a line indicated by \p line.
+     *
+     * \param[in] line The line along which to process cells
+     * \param[in] process_func Processes each cell.  process_func(elem) is
+     *    called for each cell. Processing stops if function returns false.
+     */
+    void processLineCells(const std::pair<Point, Point> line,
+                         const std::function<bool (GridPoint)>& process_cell_func) const;
 
     /*! \brief Compute the grid coordinates of a point.
      *
@@ -132,6 +162,8 @@ protected:
     GridMap m_grid;
     /*! \brief The cell (square) size. */
     coord_t m_cell_size;
+
+    grid_coord_t nonzero_sign(const grid_coord_t z) const;
 };
 
 
@@ -190,23 +222,99 @@ typename cura::coord_t SGI_THIS::toLowerCoord(const grid_coord_t& grid_coord)  c
 }
 
 SGI_TEMPLATE
-template<class ProcessFunc>
-void SGI_THIS::processFromCell(
+bool SGI_THIS::processFromCell(
     const GridPoint &grid_pt,
-    ProcessFunc &process_func) const
+    const std::function<bool (const Elem&)>& process_func) const
 {
     auto grid_range = m_grid.equal_range(grid_pt);
     for (auto iter = grid_range.first; iter != grid_range.second; ++iter)
     {
-        process_func(iter->second);
+        if (!process_func(iter->second))
+        {
+            return false;
+        }
     }
-
+    return true;
+}
+
+SGI_TEMPLATE
+void SGI_THIS::processLineCells(
+    const std::pair<Point, Point> line,
+    const std::function<bool (GridPoint)>& process_cell_func)
+{
+    static_cast<const SGI_THIS*>(this)->processLineCells(line, process_cell_func);
+}
+
+SGI_TEMPLATE
+void SGI_THIS::processLineCells(
+    const std::pair<Point, Point> line,
+    const std::function<bool (GridPoint)>& process_cell_func) const
+{
+
+    Point start = line.first;
+    Point end = line.second;
+    if (end.X < start.X)
+    { // make sure X increases between start and end
+        std::swap(start, end);
+    }
+
+    const GridPoint start_cell = toGridPoint(start);
+    const GridPoint end_cell = toGridPoint(end);
+    const coord_t y_diff = end.Y - start.Y;
+    const grid_coord_t y_dir = nonzero_sign(y_diff);
+
+    grid_coord_t x_cell_start = start_cell.X;
+    for (grid_coord_t cell_y = start_cell.Y; cell_y * y_dir <= end_cell.Y * y_dir; cell_y += y_dir)
+    { // for all Y from start to end
+        // nearest y coordinate of the cells in the next row
+        coord_t nearest_next_y = toLowerCoord(cell_y + ((nonzero_sign(cell_y) == y_dir || cell_y == 0) ? y_dir : coord_t(0)));
+        grid_coord_t x_cell_end; // the X coord of the last cell to include from this row
+        if (y_diff == 0)
+        {
+            x_cell_end = end_cell.X;
+        }
+        else
+        {
+            coord_t area = (end.X - start.X) * (nearest_next_y - start.Y);
+            // corresponding_x: the x coordinate corresponding to nearest_next_y
+            coord_t corresponding_x = start.X + area / y_diff;
+            x_cell_end = toGridCoord(corresponding_x + ((corresponding_x < 0) && ((area % y_diff) != 0)));
+            if (x_cell_end < start_cell.X)
+            { // process at least one cell!
+                x_cell_end = x_cell_start;
+            }
+        }
+
+        for (grid_coord_t cell_x = x_cell_start; cell_x <= x_cell_end; ++cell_x)
+        {
+            GridPoint grid_loc(cell_x, cell_y);
+            bool continue_ = process_cell_func(grid_loc);
+            if (!continue_)
+            {
+                return;
+            }
+            if (grid_loc == end_cell)
+            {
+                return;
+            }
+        }
+        // TODO: this causes at least a one cell overlap for each row, which
+        // includes extra cells when crossing precisely on the corners
+        // where positive slope where x > 0 and negative slope where x < 0
+        x_cell_start = x_cell_end;
+    }
+    assert(false && "We should have returned already before here!");
+}
+
+SGI_TEMPLATE
+typename SGI_THIS::grid_coord_t SGI_THIS::nonzero_sign(const grid_coord_t z) const
+{
+    return (z >= 0) - (z < 0);
 }
 
 SGI_TEMPLATE
-template<class ProcessFunc>
 void SGI_THIS::processNearby(const Point &query_pt, coord_t radius,
-                             ProcessFunc &process_func) const
+                             const std::function<bool (const Elem&)>& process_func) const
 {
     Point min_loc(query_pt.X - radius, query_pt.Y - radius);
     Point max_loc(query_pt.X + radius, query_pt.Y + radius);
@@ -219,19 +327,35 @@ void SGI_THIS::processNearby(const Point &query_pt, coord_t radius,
         for (coord_t grid_x = min_grid.X; grid_x <= max_grid.X; ++grid_x)
         {
             GridPoint grid_pt(grid_x,grid_y);
-            processFromCell(grid_pt, process_func);
+            bool continue_ = processFromCell(grid_pt, process_func);
+            if (!continue_)
+            {
+                return;
+            }
         }
     }
 }
 
+SGI_TEMPLATE
+void SGI_THIS::processLine(const std::pair<Point, Point> query_line,
+                            const std::function<bool (const Elem&)>& process_elem_func) const
+{
+    const std::function<bool (const GridPoint&)> process_cell_func = [&process_elem_func, this](GridPoint grid_loc)
+        {
+            return processFromCell(grid_loc, process_elem_func);
+        };
+    processLineCells(query_line, process_cell_func);
+}
+
 SGI_TEMPLATE
 std::vector<typename SGI_THIS::Elem>
 SGI_THIS::getNearby(const Point &query_pt, coord_t radius) const
 {
     std::vector<Elem> ret;
-    auto process_func = [&ret](const Elem &elem)
+    const std::function<bool (const Elem&)> process_func = [&ret](const Elem &elem)
         {
             ret.push_back(elem);
+            return true;
         };
     processNearby(query_pt, radius, process_func);
     return ret;
@@ -252,12 +376,12 @@ bool SGI_THIS::getNearest(
 {
     bool found = false;
     int64_t best_dist2 = static_cast<int64_t>(radius) * radius;
-    auto process_func =
+    const std::function<bool (const Elem&)> process_func =
         [&query_pt, &elem_nearest, &found, &best_dist2, &precondition](const Elem &elem)
         {
             if (!precondition(elem))
             {
-                return;
+                return true;
             }
             int64_t dist2 = vSize2(elem.point - query_pt);
             if (dist2 < best_dist2)
@@ -266,6 +390,7 @@ bool SGI_THIS::getNearest(
                 elem_nearest = elem;
                 best_dist2 = dist2;
             }
+            return true;
         };
     processNearby(query_pt, radius, process_func);
     return found;

src/utils/SparseLineGrid.h

@@ -6,6 +6,7 @@
 #include <cassert>
 #include <unordered_map>
 #include <vector>
+#include <functional>
 
 #include "intpoint.h"
 #include "SparseGrid.h"
@@ -50,7 +51,6 @@ protected:
 
     /*! \brief Accessor for getting locations from elements. */
     Locator m_locator;
-    grid_coord_t nonzero_sign(grid_coord_t z);
 };
 
 
@@ -68,61 +68,19 @@ SGI_TEMPLATE
 void SGI_THIS::insert(const Elem &elem)
 {
     const std::pair<Point, Point> line = m_locator(elem);
-    Point start = line.first;
-    Point end = line.second;
-    if (end.X < start.X)
-    { // make sure X increases between start and end
-        std::swap(start, end);
-    }
-
-    const GridPoint start_cell = SparseGrid<ElemT>::toGridPoint(start);
-    const GridPoint end_cell = SparseGrid<ElemT>::toGridPoint(end);
-    const coord_t y_diff = end.Y - start.Y;
-    const grid_coord_t y_dir = nonzero_sign(y_diff);
-
-    grid_coord_t x_cell_start = start_cell.X;
-    for (grid_coord_t cell_y = start_cell.Y; cell_y * y_dir <= end_cell.Y * y_dir; cell_y += y_dir)
-    { // for all Y from start to end
-        // nearest y coordinate of the cells in the next row
-        coord_t nearest_next_y = SparseGrid<ElemT>::toLowerCoord(cell_y + ((nonzero_sign(cell_y) == y_dir || cell_y == 0) ? y_dir : coord_t(0)));
-        grid_coord_t x_cell_end; // the X coord of the last cell to include from this row
-        if (y_diff == 0)
+    using GridMap = std::unordered_multimap<GridPoint, Elem>;
+    // below is a workaround for the fact that lambda functions cannot access private or protected members
+    // first we define a lambda which works on any GridMap and then we bind it to the actual protected GridMap of the parent class
+    std::function<bool (GridMap*, const GridPoint)> process_cell_func_ = [&elem, this](GridMap* m_grid, const GridPoint grid_loc)
         {
-            x_cell_end = end_cell.X;
-        }
-        else
-        {
-            coord_t area = (end.X - start.X) * (nearest_next_y - start.Y);
-            // corresponding_x: the x coordinate corresponding to nearest_next_y
-            coord_t corresponding_x = start.X + area / y_diff;
-            x_cell_end = SparseGrid<ElemT>::toGridCoord(corresponding_x + ((corresponding_x < 0) && ((area % y_diff) != 0)));
-            if (x_cell_end < start_cell.X)
-            { // process at least one cell!
-                x_cell_end = x_cell_start;
-            }
-        }
+            m_grid->emplace(grid_loc, elem);
+            return true;
+        };
+    using namespace std::placeholders;  // for _1, _2, _3...
+    GridMap* m_grid = &(this->m_grid);
+    std::function<bool (const GridPoint)> process_cell_func(std::bind(process_cell_func_, m_grid, _1));
 
-        for (grid_coord_t cell_x = x_cell_start; cell_x <= x_cell_end; ++cell_x)
-        {
-            GridPoint grid_loc(cell_x, cell_y);
-            SparseGrid<ElemT>::m_grid.emplace(grid_loc, elem);
-            if (grid_loc == end_cell)
-            {
-                return;
-            }
-        }
-        // TODO: this causes at least a one cell overlap for each row, which
-        // includes extra cells when crossing precisely on the corners
-        // where positive slope where x > 0 and negative slope where x < 0
-        x_cell_start = x_cell_end;
-    }
-    assert(false && "We should have returned already before here!");
-}
-
-SGI_TEMPLATE
-typename SGI_THIS::grid_coord_t SGI_THIS::nonzero_sign(grid_coord_t z)
-{
-    return (z >= 0) - (z < 0);
+    SparseGrid<ElemT>::processLineCells(line, process_cell_func);
 }
 
 SGI_TEMPLATE
@@ -132,16 +90,16 @@ void SGI_THIS::debugHTML(std::string filename)
     for (std::pair<GridPoint, ElemT> cell:  SparseGrid<ElemT>::m_grid)
     {
         aabb.include(SparseGrid<ElemT>::toLowerCorner(cell.first));
-        aabb.include(SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(nonzero_sign(cell.first.X), nonzero_sign(cell.first.Y))));
+        aabb.include(SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(SparseGrid<ElemT>::nonzero_sign(cell.first.X), SparseGrid<ElemT>::nonzero_sign(cell.first.Y))));
     }
     SVG svg(filename.c_str(), aabb);
     for (std::pair<GridPoint, ElemT> cell:  SparseGrid<ElemT>::m_grid)
     {
         // doesn't draw cells at x = 0 or y = 0 correctly (should be double size)
         Point lb = SparseGrid<ElemT>::toLowerCorner(cell.first);
-        Point lt = SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(0, nonzero_sign(cell.first.Y)));
-        Point rt = SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(nonzero_sign(cell.first.X), nonzero_sign(cell.first.Y)));
-        Point rb = SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(nonzero_sign(cell.first.X), 0));
+        Point lt = SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(0, SparseGrid<ElemT>::nonzero_sign(cell.first.Y)));
+        Point rt = SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(SparseGrid<ElemT>::nonzero_sign(cell.first.X), SparseGrid<ElemT>::nonzero_sign(cell.first.Y)));
+        Point rb = SparseGrid<ElemT>::toLowerCorner(cell.first + GridPoint(SparseGrid<ElemT>::nonzero_sign(cell.first.X), 0));
         if (lb.X == 0)
         {
             lb.X = -SparseGrid<ElemT>::m_cell_size;

src/utils/SparsePointGridInclusive.h

@@ -109,9 +109,10 @@ std::vector<Val>
 SG_THIS::getNearbyVals(const Point &query_pt, coord_t radius) const
 {
     std::vector<Val> ret;
-    auto process_func = [&ret](const typename SG_THIS::Elem &elem)
+    std::function<bool (const SparsePointGridInclusiveImpl::SparsePointGridInclusiveElem<Val>&)> process_func = [&ret](const typename SG_THIS::Elem &elem)
         {
             ret.push_back(elem.val);
+            return true;
         };
     this->processNearby(query_pt, radius, process_func);
     return ret;

src/utils/algorithm.h

@@ -0,0 +1,47 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+#ifndef UTILS_ALGORITHM_H
+#define UTILS_ALGORITHM_H
+
+#include <algorithm>
+#include <vector>
+#include <functional>
+#include <numeric>
+
+// extensions to algorithm.h from the standard library
+
+namespace cura
+{
+
+/*!
+ * Get the order of a vector: the sorted indices of a vector
+ * 
+ * {1.6, 1.8, 1.7} returns {1, 3, 2} meaning {in[1], in[3], in[2]} is a sorted
+ * vector
+ * 
+ * Thanks to Lukasz Wiklendt
+ * 
+ * \param in The vector for which to get the order
+ * \return An ordered vector of indices into \p in 
+ */
+template<typename T>
+std::vector<size_t> order(const std::vector<T> &in)
+{
+    // initialize original index locations
+    std::vector<size_t> order(in.size());
+    std::iota(order.begin(), order.end(), 0); // fill vector with 1, 2, 3,.. etc
+
+    // sort indexes based on comparing values in v
+    std::sort(order.begin(), order.end(),
+        [&in](size_t i1, size_t i2)
+        {
+            return in[i1] < in[i2];
+        }
+    );
+
+    return order;
+}
+
+} // namespace cura
+
+#endif // UTILS_ALGORITHM_H
+

src/utils/intpoint.h

@@ -285,6 +285,66 @@ public:
     }
 };
 
+class Point3Matrix
+{
+public:
+    double matrix[9];
+
+    Point3Matrix()
+    {
+        matrix[0] = 1;
+        matrix[1] = 0;
+        matrix[2] = 0;
+        matrix[3] = 0;
+        matrix[4] = 1;
+        matrix[5] = 0;
+        matrix[6] = 0;
+        matrix[7] = 0;
+        matrix[8] = 1;
+    }
+
+    /*!
+     * Initializes the top left corner with the values of \p b
+     * and the rest as if it's a unit matrix
+     */
+    Point3Matrix(const PointMatrix& b)
+    {
+        matrix[0] = b.matrix[0];
+        matrix[1] = b.matrix[1];
+        matrix[2] = 0;
+        matrix[3] = b.matrix[2];
+        matrix[4] = b.matrix[3];
+        matrix[5] = 0;
+        matrix[6] = 0;
+        matrix[7] = 0;
+        matrix[8] = 1;
+    }
+
+    Point3 apply(const Point3 p) const
+    {
+        return Point3(p.x * matrix[0] + p.y * matrix[1] + p.z * matrix[2]
+                    , p.x * matrix[3] + p.y * matrix[4] + p.z * matrix[5]
+                    , p.x * matrix[6] + p.y * matrix[7] + p.z * matrix[8]);
+    }
+
+    Point3Matrix compose(const Point3Matrix& b)
+    {
+        Point3Matrix ret;
+        for (int outx = 0; outx < 3; outx++)
+        {
+            for (int outy = 0; outy < 3; outy++)
+            {
+                ret.matrix[outy * 3 + outx] = 0;
+                for (int in = 0; in < 3; in++)
+                {
+                    ret.matrix[outy * 3 + outx] += matrix[outy * 3 + in] * b.matrix[in * 3 + outx];
+                }
+            }
+        }
+        return ret;
+    }
+};
+
 
 inline Point3 operator+(const Point3& p3, const Point& p2) {
     return Point3(p3.x + p2.X, p3.y + p2.Y, p3.z);

src/utils/linearAlg2D.h

@@ -216,7 +216,23 @@ public:
                 || getDist2FromLineSegment(c, a, d) <= max_dist2
                 || getDist2FromLineSegment(c, b, d) <= max_dist2;
     }
-    
+
+    /*!
+     * Check whether two line segments collide.
+     * 
+     * \warning Edge cases (end points of line segments fall on other line segment) register as a collision.
+     * 
+     * \note All points are assumed to be transformed by the transformation matrix of the vector from \p a_from to \p a_to.
+     * I.e. a is a vertical line; the Y of \p a_from_transformed is the same as the Y of \p a_to_transformed.
+     * 
+     * \param a_from_transformed The transformed from location of line a
+     * \param a_from_transformed The transformed to location of line a
+     * \param b_from_transformed The transformed from location of line b
+     * \param b_from_transformed The transformed to location of line b
+     * \return Whether the two line segments collide
+     */
+    static bool lineSegmentsCollide(Point a_from_transformed, Point a_to_transformed, Point b_from_transformed, Point b_to_transformed);
+
     /*!
      * Compute the angle between two consecutive line segments.
      * 

src/utils/optional.h

@@ -3,6 +3,8 @@
 #define UTILS_OPTIONAL_H
 
 #include <algorithm> // swap
+#include <type_traits> // enable_if  is_same
+#include <cassert> // assert
 
 namespace std
 {
@@ -19,6 +21,7 @@ namespace std
 template<typename T>
 class optional
 {
+protected:
     T* instance;
 public:
     optional() //!< create an optional value which is not instantiated
@@ -42,11 +45,11 @@ public:
         other.instance = nullptr;
     }
     template<class... Args>
-    constexpr explicit optional(bool not_used, Args&&... args ) //!< construct the value in place
+    constexpr explicit optional(bool, Args&&... args ) //!< construct the value in place
     : instance(new T(args...))
     {
     }
-    ~optional() //!< simple destructor
+    virtual ~optional() //!< simple destructor
     {
         if (instance)
         {
@@ -59,7 +62,7 @@ public:
      * \param null_ptr exactly [nullptr]
      * \return this
      */
-    optional& operator=(std::nullptr_t null_ptr)
+    optional& operator=(std::nullptr_t)
     {
         if (instance)
         {
@@ -72,13 +75,13 @@ public:
     {
         if (instance)
         {
-            delete instance;
             if (other.instance)
             {
                 *instance = *other.instance;
             }
             else
             {
+                delete instance;
                 instance = nullptr;
             }
         }
@@ -101,12 +104,14 @@ public:
         other.instance = nullptr;
         return *this;
     }
-    template<class U> 
+    template<class U = T
+        , typename = typename std::enable_if<std::is_assignable<T&, U>::value>::type // type U is T, T& or T&&
+        >
     optional& operator=(U&& value)
     {
         if (instance)
         {
-            *instance = value;
+            *instance = std::forward<U>(value);
         }
         else
         {
@@ -116,10 +121,12 @@ public:
     }
     constexpr T* operator->() const
     {
+        assert(instance && "Instance should be instantiated!");
         return instance;
     }
     constexpr T& operator*() const&
     {
+        assert(instance && "Instance should be instantiated!");
         return *instance;
     }
     constexpr explicit operator bool() const

src/utils/orderOptimizer.h

@@ -0,0 +1,99 @@
+/** Copyright (C) 2016 Ultimaker B.V. - Released under terms of the AGPLv3 License */
+#ifndef UTILS_ORDER_OPTIMIZER_H
+#define UTILS_ORDER_OPTIMIZER_H
+
+#include <stdint.h>
+#include <vector>
+#include <list>
+#include <utility> // pair
+#include "intpoint.h"
+
+namespace cura {
+ 
+/*!
+ * Order optimization class.
+ * 
+ * Utility class for optimizing the path order by minimizing the cyclic distance traveled between several items.
+ * 
+ * The path is heuristically optimized in a way such that each node is visited and the salesman which is travelling ends up where he started.
+ */
+template <typename T>
+class OrderOptimizer
+{
+public:
+    std::vector<std::pair<const Point, T>> items; //!< the items in arbitrary order
+
+    OrderOptimizer()
+    {
+    }
+
+    void addItem(const Point location, const T item);
+
+    /*!
+     * Optimize the order of \ref OrderOptimizer::items
+     * \return A vector of the ordered indices into \ref OrderOptimizer::items
+     */
+    std::list<unsigned int> optimize();
+
+
+};
+
+template <typename T>
+void OrderOptimizer<T>::addItem(const Point location, const T item)
+{
+    this->items.emplace_back(location, item);
+}
+
+template <typename T>
+std::list<unsigned int> OrderOptimizer<T>::optimize()
+{
+    // least detour insertion algorithm
+    std::list<unsigned int> order;
+    if (items.size() == 0)
+    {
+        return order;
+    }
+    order.push_back(0u);
+    if (items.size() == 1)
+    {
+        return order;
+    }
+    order.push_back(1u);
+    if (items.size() == 2)
+    {
+        return order;
+    }
+    order.push_back(2u);
+
+    for (unsigned int item_idx = 3; item_idx < items.size(); item_idx++)
+    {
+        Point to_insert_item_location = items[item_idx].first;
+
+        // find best_item_to_insert_before
+        std::list<unsigned int>::iterator best_item_to_insert_before = order.begin();
+        coord_t best_detour_dist = vSize(items[*best_item_to_insert_before].first - to_insert_item_location)
+                                + vSize(to_insert_item_location - items[order.back()].first)
+                                - vSize(items[*best_item_to_insert_before].first - items[order.back()].first);
+        std::list<unsigned int>::iterator prev = order.begin();
+        for (std::list<unsigned int>::iterator nearby = ++order.begin(); nearby != order.end(); ++nearby)
+        {
+            coord_t detour_dist = vSize(items[*nearby].first - to_insert_item_location)
+                                + vSize(to_insert_item_location - items[*prev].first)
+                                - vSize(items[*nearby].first - items[*prev].first);
+            if (detour_dist < best_detour_dist)
+            {
+                best_detour_dist = detour_dist;
+                best_item_to_insert_before = nearby;
+            }
+            prev = nearby;
+        }
+
+        order.insert(best_item_to_insert_before, item_idx);
+    }
+    return order;
+}
+
+
+}//namespace cura
+
+#endif//UTILS_ORDER_OPTIMIZER_H

src/utils/polygon.cpp

@@ -83,6 +83,21 @@ unsigned int Polygons::pointCount() const
 }
 
 bool Polygons::inside(Point p, bool border_result) const
+{
+    int poly_count_inside = 0;
+    for (const ClipperLib::Path& poly : *this)
+    {
+        const int is_inside_this_poly = ClipperLib::PointInPolygon(p, poly);
+        if (is_inside_this_poly == -1)
+        {
+            return border_result;
+        }
+        poly_count_inside += is_inside_this_poly;
+    }
+    return (poly_count_inside % 2) == 1;
+}
+
+bool Polygons::insideOld(Point p, bool border_result) const
 {
     const Polygons& thiss = *this;
     if (size() < 1)

src/utils/polygon.h

@@ -11,9 +11,11 @@
 #include <limits> // int64_t.min
 #include <list>
 
+#include <initializer_list>
+
 #include "intpoint.h"
 
-//#define CHECK_POLY_ACCESS
+#define CHECK_POLY_ACCESS
 #ifdef CHECK_POLY_ACCESS
 #define POLY_ASSERT(e) assert(e)
 #else
@@ -52,7 +54,7 @@ public:
 
     Point& operator[] (unsigned int index) const
     {
-        POLY_ASSERT(index < size());
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
         return (*path)[index];
     }
 
@@ -85,7 +87,7 @@ public:
 
     void remove(unsigned int index)
     {
-        POLY_ASSERT(index < size());
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
         path->erase(path->begin() + index);
     }
 
@@ -407,7 +409,7 @@ public:
 
     PolygonRef operator[] (unsigned int index)
     {
-        POLY_ASSERT(index < size());
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
         return PolygonRef(paths[index]);
     }
     const PolygonRef operator[] (unsigned int index) const
@@ -430,11 +432,23 @@ public:
     {
         return paths.end();
     }
+    /*!
+     * Remove a polygon from the list and move the last polygon to its place
+     * 
+     * \warning changes the order of the polygons!
+     */
     void remove(unsigned int index)
     {
-        POLY_ASSERT(index < size());
-        paths.erase(paths.begin() + index);
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
+        if (index < paths.size() - 1)
+        {
+            paths[index] = std::move(paths.back());
+        }
+        paths.resize(paths.size() - 1);
     }
+    /*!
+     * Remove a range of polygons
+     */
     void erase(ClipperLib::Paths::iterator start, ClipperLib::Paths::iterator end)
     {
         paths.erase(start, end);
@@ -456,6 +470,13 @@ public:
         for(unsigned int n=0; n<other.paths.size(); n++)
             paths.push_back(other.paths[n]);
     }
+    /*!
+     * Add a 'polygon' consisting of two points
+     */
+    void addLine(const Point from, const Point to)
+    {
+        paths.emplace_back((std::initializer_list<Point>){from, to});
+    }
 
     template<typename... Args>
     void emplace_back(Args... args)
@@ -514,6 +535,20 @@ public:
         clipper.Execute(ClipperLib::ctIntersection, ret.paths);
         return ret;
     }
+    /*!
+     * Clips input line segments by this Polygons.
+     * \param other Input line segments to be cropped
+     * \return the resulting interior line segments
+     */
+    ClipperLib::PolyTree lineSegmentIntersection(const Polygons& other) const
+    {
+        ClipperLib::PolyTree ret;
+        ClipperLib::Clipper clipper(clipper_init);
+        clipper.AddPaths(paths, ClipperLib::ptClip, true);
+        clipper.AddPaths(other.paths, ClipperLib::ptSubject, false);
+        clipper.Execute(ClipperLib::ctIntersection, ret);
+        return ret;
+    }
     Polygons xorPolygons(const Polygons& other) const
     {
         Polygons ret;
@@ -537,6 +572,20 @@ public:
         return ret;
     }
     
+    /*!
+     * Check if we are inside the polygon.
+     * 
+     * We do this by counting the number of polygons inside which this point lies.
+     * An odd number is inside, while an even number is outside.
+     * 
+     * Returns false if outside, true if inside; if the point lies exactly on the border, will return \p border_result.
+     * 
+     * \param p The point for which to check if it is inside this polygon
+     * \param border_result What to return when the point is exactly on the border
+     * \return Whether the point \p p is inside this polygon (or \p border_result when it is on the border)
+     */
+    bool inside(Point p, bool border_result = false) const;
+
     /*!
      * Check if we are inside the polygon. We do this by tracing from the point towards the positive X direction,
      * every line we cross increments the crossings counter. If we have an even number of crossings then we are not inside the polygon.
@@ -549,11 +598,13 @@ public:
      * 
      * Returns false if outside, true if inside; if the point lies exactly on the border, will return \p border_result.
      * 
+     * \deprecated This function is old and no longer used. instead use \ref Polygons::inside
+     * 
      * \param p The point for which to check if it is inside this polygon
      * \param border_result What to return when the point is exactly on the border
      * \return Whether the point \p p is inside this polygon (or \p border_result when it is on the border)
      */
-    bool inside(Point p, bool border_result = false) const;
+    bool insideOld(Point p, bool border_result = false) const;
     
     /*!
      * Find the polygon inside which point \p p resides. 

src/utils/polygonUtils.cpp

@@ -126,15 +126,20 @@ Point PolygonUtils::getBoundaryPointWithOffset(PolygonRef poly, unsigned int poi
 
 Point PolygonUtils::moveInsideDiagonally(ClosestPolygonPoint point_on_boundary, int64_t inset)
 {
-    Point p0 = point_on_boundary.poly[point_on_boundary.point_idx];
-    Point p1 = point_on_boundary.poly[(point_on_boundary.point_idx + 1) % point_on_boundary.poly.size()];
+    if (!point_on_boundary.isValid())
+    {
+        return no_point;
+    }
+    PolygonRef poly = *point_on_boundary.poly;
+    Point p0 = poly[point_on_boundary.point_idx];
+    Point p1 = poly[(point_on_boundary.point_idx + 1) % poly.size()];
     if (vSize2(p0 - point_on_boundary.location) < vSize2(p1 - point_on_boundary.location))
     {
-        return point_on_boundary.location + normal(getVertexInwardNormal(point_on_boundary.poly, point_on_boundary.point_idx), inset);
+        return point_on_boundary.location + normal(getVertexInwardNormal(poly, point_on_boundary.point_idx), inset);
     }
     else
     {
-        return point_on_boundary.location + normal(getVertexInwardNormal(point_on_boundary.poly, (point_on_boundary.point_idx + 1) % point_on_boundary.poly.size()), inset);
+        return point_on_boundary.location + normal(getVertexInwardNormal(poly, (point_on_boundary.point_idx + 1) % poly.size()), inset);
     }
 }
 
@@ -144,23 +149,39 @@ unsigned int PolygonUtils::moveOutside(const Polygons& polygons, Point& from, in
     return moveInside(polygons, from, -distance, maxDist2);
 }
 
-ClosestPolygonPoint PolygonUtils::moveInside2(const Polygons& polygons, Point& from, const int distance, const int64_t max_dist2, const std::function<int(Point)>& penalty_function)
+ClosestPolygonPoint PolygonUtils::moveInside2(const Polygons& polygons, Point& from, const int distance, const int64_t max_dist2, const Polygons* loc_to_line_polygons, const LocToLineGrid* loc_to_line_grid, const std::function<int(Point)>& penalty_function)
 {
-    const ClosestPolygonPoint closest_polygon_point = findClosest(from, polygons, penalty_function);
-    return _moveInside2(closest_polygon_point, distance, from, max_dist2);
+    std::optional<ClosestPolygonPoint> closest_polygon_point;
+    if (loc_to_line_grid)
+    {
+        closest_polygon_point = findClose(from, *loc_to_line_polygons, *loc_to_line_grid, penalty_function);
+    }
+    if (!closest_polygon_point)
+    {
+        closest_polygon_point = findClosest(from, polygons, penalty_function);
+    }
+    return _moveInside2(*closest_polygon_point, distance, from, max_dist2);
 }
 
-ClosestPolygonPoint PolygonUtils::moveInside2(const PolygonRef polygon, Point& from, const int distance, const int64_t max_dist2, const std::function<int(Point)>& penalty_function)
+ClosestPolygonPoint PolygonUtils::moveInside2(const Polygons& loc_to_line_polygons, const PolygonRef polygon, Point& from, const int distance, const int64_t max_dist2, const LocToLineGrid* loc_to_line_grid, const std::function<int(Point)>& penalty_function)
 {
-    const ClosestPolygonPoint closest_polygon_point = findClosest(from, polygon, penalty_function);
-    return _moveInside2(closest_polygon_point, distance, from, max_dist2);
+    std::optional<ClosestPolygonPoint> closest_polygon_point;
+    if (loc_to_line_grid)
+    {
+        closest_polygon_point = findClose(from, loc_to_line_polygons, *loc_to_line_grid, penalty_function);
+    }
+    if (!closest_polygon_point)
+    {
+        closest_polygon_point = findClosest(from, polygon, penalty_function);
+    }
+    return _moveInside2(*closest_polygon_point, distance, from, max_dist2);
 }
 
 ClosestPolygonPoint PolygonUtils::_moveInside2(const ClosestPolygonPoint& closest_polygon_point, const int distance, Point& from, const int64_t max_dist2)
 {
-    if (closest_polygon_point.point_idx == NO_INDEX)
+    if (!closest_polygon_point.isValid())
     {
-        return ClosestPolygonPoint(closest_polygon_point.poly); // stub with invalid indices to signify we haven't found any
+        return ClosestPolygonPoint(); // stub with invalid indices to signify we haven't found any
     }
     const Point v_boundary_from = from - closest_polygon_point.location;
     Point result = moveInside(closest_polygon_point, distance);
@@ -182,7 +203,7 @@ ClosestPolygonPoint PolygonUtils::_moveInside2(const ClosestPolygonPoint& closes
     {
         if (vSize2(v_boundary_from) > max_dist2)
         {
-            return ClosestPolygonPoint(closest_polygon_point.poly); // stub with invalid indices to signify we haven't found any
+            return ClosestPolygonPoint(*closest_polygon_point.poly); // stub with invalid indices to signify we haven't found any
         }
         else
         {
@@ -315,11 +336,15 @@ Point PolygonUtils::moveOutside(const ClosestPolygonPoint& cpp, const int distan
 
 Point PolygonUtils::moveInside(const ClosestPolygonPoint& cpp, const int distance)
 {
+    if (!cpp.isValid())
+    {
+        return no_point;
+    }
     if (distance == 0)
     { // the point which is assumed to be on the boundary doesn't have to be moved
         return cpp.location;
     }
-    const PolygonRef poly = cpp.poly;
+    const PolygonRef poly = *cpp.poly;
     unsigned int point_idx = cpp.point_idx;
     const Point& on_boundary = cpp.location;
 
@@ -355,14 +380,19 @@ Point PolygonUtils::moveInside(const ClosestPolygonPoint& cpp, const int distanc
     }
 }
 
-ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons, Point& from, int preferred_dist_inside, int64_t max_dist2, const std::function<int(Point)>& penalty_function)
+ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons, Point& from, int preferred_dist_inside, int64_t max_dist2, const Polygons* loc_to_line_polygons, const LocToLineGrid* loc_to_line_grid, const std::function<int(Point)>& penalty_function)
 {
-    ClosestPolygonPoint closest_polygon_point = moveInside2(polygons, from, preferred_dist_inside, max_dist2, penalty_function);
-    if (closest_polygon_point.point_idx == NO_INDEX)
+    ClosestPolygonPoint closest_polygon_point = moveInside2(polygons, from, preferred_dist_inside, max_dist2, loc_to_line_polygons, loc_to_line_grid, penalty_function);
+    return ensureInsideOrOutside(polygons, from, closest_polygon_point, preferred_dist_inside, max_dist2, loc_to_line_polygons, loc_to_line_grid, penalty_function);
+}
+
+ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons, Point& from, ClosestPolygonPoint& closest_polygon_point, int preferred_dist_inside, int64_t max_dist2, const Polygons* loc_to_line_polygons, const LocToLineGrid* loc_to_line_grid, const std::function<int(Point)>& penalty_function)
+{
+    if (!closest_polygon_point.isValid())
     {
-        return ClosestPolygonPoint(polygons[0]); // we couldn't move inside
+        return ClosestPolygonPoint(); // we couldn't move inside
     }
-    PolygonRef closest_poly = closest_polygon_point.poly;
+    PolygonRef closest_poly = *closest_polygon_point.poly;
     bool is_outside_boundary = closest_poly.orientation();
 
     {
@@ -376,7 +406,7 @@ ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons
 
     // try once more with half the preferred distance inside
     int64_t max_dist2_here = std::numeric_limits<int64_t>::max(); // we already concluded we are close enough to the closest_poly
-    moveInside2(closest_poly, from, preferred_dist_inside / 2, max_dist2_here, penalty_function);
+    moveInside2(*loc_to_line_polygons, closest_poly, from, preferred_dist_inside / 2, max_dist2_here, loc_to_line_grid, penalty_function);
     bool is_inside = closest_poly.inside(from) == is_outside_boundary; // inside a hole is outside the part
     if (is_inside == (preferred_dist_inside > 0))
     { // we ended up on the right side of the polygon
@@ -390,10 +420,10 @@ ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons
         Polygons insetted = closest_poly.offset(offset / 2); // perform less inset, because chances are (thin parts of) the polygon will disappear, given that moveInside did an overshoot
         if (insetted.size() == 0)
         {
-            return ClosestPolygonPoint(polygons[0]); // we couldn't move inside
+            return ClosestPolygonPoint(); // we couldn't move inside
         }
         ClosestPolygonPoint inside = findClosest(from, insetted, penalty_function);
-        if (inside.point_idx != NO_INDEX)
+        if (inside.isValid())
         {
             bool is_inside = polygons.inside(inside.location) == is_outside_boundary; // inside a hole is outside the part
             if (is_inside != (preferred_dist_inside > 0))
@@ -427,16 +457,16 @@ ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons
                         }
                     }
                     svg.writeComment("From location");
-                    svg.writePoint(from, false, 5, SVG::Color::GREEN);
+                    svg.writePoint(from, true, 5, SVG::Color::GREEN);
                     svg.writeComment("Location computed to be inside the black polygon");
-                    svg.writePoint(inside.location, false, 5, SVG::Color::RED);
+                    svg.writePoint(inside.location, true, 5, SVG::Color::RED);
                 }
                 catch(...)
                 {
                 }
                 logError("Clipper::offset failed. See generated debug.html!\n\tBlack is original\n\tBlue is offsetted polygon\n");
 #endif
-                return ClosestPolygonPoint(polygons[0]);
+                return ClosestPolygonPoint();
             }
             from = inside.location;
         } // otherwise we just return the closest polygon point without modifying the from location
@@ -447,8 +477,12 @@ ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons
 
 void PolygonUtils::findSmallestConnection(ClosestPolygonPoint& poly1_result, ClosestPolygonPoint& poly2_result, int sample_size)
 {
-    PolygonRef poly1 = poly1_result.poly;
-    PolygonRef poly2 = poly2_result.poly;
+    if (!poly1_result.isValid() || !poly2_result.isValid())
+    {
+        return;
+    }
+    PolygonRef poly1 = *poly1_result.poly;
+    PolygonRef poly2 = *poly2_result.poly;
     if (poly1.size() == 0 || poly2.size() == 0)
     {
         return;
@@ -477,8 +511,12 @@ void PolygonUtils::findSmallestConnection(ClosestPolygonPoint& poly1_result, Clo
 
 void PolygonUtils::walkToNearestSmallestConnection(ClosestPolygonPoint& poly1_result, ClosestPolygonPoint& poly2_result)
 {
-    PolygonRef poly1 = poly1_result.poly;
-    PolygonRef poly2 = poly2_result.poly;
+    if (!poly1_result.isValid() || !poly2_result.isValid())
+    {
+        return;
+    }
+    PolygonRef poly1 = *poly1_result.poly;
+    PolygonRef poly2 = *poly2_result.poly;
     if (poly1_result.point_idx < 0 || poly2_result.point_idx < 0)
     {
         return;
@@ -502,12 +540,12 @@ void PolygonUtils::walkToNearestSmallestConnection(ClosestPolygonPoint& poly1_re
 ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, PolygonRef polygon, int start_idx)
 {
     ClosestPolygonPoint forth = findNearestClosest(from, polygon, start_idx, 1);
-    if (forth.point_idx == NO_INDEX)
+    if (!forth.isValid())
     {
         return forth; // stop computation
     }
     ClosestPolygonPoint back = findNearestClosest(from, polygon, start_idx, -1);
-    assert(back.point_idx != NO_INDEX);
+    assert(back.isValid());
     if (vSize2(forth.location - from) < vSize2(back.location - from))
     {
         return forth;
@@ -556,14 +594,27 @@ ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, PolygonRef poly
 
 ClosestPolygonPoint PolygonUtils::findClosest(Point from, const Polygons& polygons, const std::function<int(Point)>& penalty_function)
 {
-    ClosestPolygonPoint none(from, -1, polygons[0], -1);
+    ClosestPolygonPoint none;
     
-    if (polygons.size() == 0) return none;
-    PolygonRef aPolygon = polygons[0];
-    if (aPolygon.size() == 0) return none;
-    Point aPoint = aPolygon[0];
-
-    ClosestPolygonPoint best(aPoint, 0, aPolygon, 0);
+    if (polygons.size() == 0)
+    {
+        return none;
+    }
+    PolygonRef any_polygon = polygons[0];
+    unsigned int any_poly_idx;
+    for (any_poly_idx = 0; any_poly_idx < polygons.size(); any_poly_idx++)
+    { // find first point in all polygons
+        if (polygons[any_poly_idx].size() > 0)
+        {
+            any_polygon = polygons[any_poly_idx];
+            break;
+        }
+    }
+    if (any_polygon.size() == 0)
+    {
+        return none;
+    }
+    ClosestPolygonPoint best(any_polygon[0], 0, any_polygon, any_poly_idx);
 
     int64_t closestDist2_score = vSize2(from - best.location) + penalty_function(best.location);
     
@@ -572,7 +623,7 @@ ClosestPolygonPoint PolygonUtils::findClosest(Point from, const Polygons& polygo
         const PolygonRef poly = polygons[ply];
         if (poly.size() == 0) continue;
         ClosestPolygonPoint closest_here = findClosest(from, poly, penalty_function);
-        if (closest_here.point_idx == NO_INDEX)
+        if (!closest_here.isValid())
         {
             continue;
         }
@@ -658,7 +709,7 @@ unsigned int PolygonUtils::findNearestVert(const Point from, const PolygonRef po
 }
 
 
-SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>* PolygonUtils::createLocToLineGrid(const Polygons& polygons, int square_size)
+LocToLineGrid* PolygonUtils::createLocToLineGrid(const Polygons& polygons, int square_size)
 {
     unsigned int n_points = 0;
     for (const auto& poly : polygons)
@@ -666,7 +717,7 @@ SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>* PolygonUti
         n_points += poly.size();
     }
 
-    SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>* ret = new SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>(square_size, n_points);
+    LocToLineGrid* ret = new LocToLineGrid(square_size, n_points);
 
     for (unsigned int poly_idx = 0; poly_idx < polygons.size(); poly_idx++)
     {
@@ -689,7 +740,7 @@ SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>* PolygonUti
  */
 std::optional<ClosestPolygonPoint> PolygonUtils::findClose(
     Point from, const Polygons& polygons,
-    const SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>& loc_to_line,
+    const LocToLineGrid& loc_to_line,
     const std::function<int(Point)>& penalty_function)
 {
     std::vector<PolygonsPointIndex> near_lines =
@@ -728,7 +779,7 @@ std::optional<ClosestPolygonPoint> PolygonUtils::findClose(
 
 std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> PolygonUtils::findClose(
     const PolygonRef from, const Polygons& destination,
-    const SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>& destination_loc_to_line,
+    const LocToLineGrid& destination_loc_to_line,
     const std::function<int(Point)>& penalty_function)
 {
     std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> ret;
@@ -842,34 +893,61 @@ bool PolygonUtils::getNextPointWithDistance(Point from, int64_t dist, const Poly
 }
 
 
+bool PolygonUtils::polygonCollidesWithLineSegment(const Point from, const Point to, const LocToLineGrid& loc_to_line, PolygonsPointIndex* collision_result)
+{
+    bool ret = false;
+    Point diff = to - from;
+    if (vSize2(diff) < 2)
+    { // transformation matrix would fail
+        return false;
+    }
 
-bool PolygonUtils::polygonCollidesWithlineSegment(const PolygonRef poly, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix)
+    PointMatrix transformation_matrix = PointMatrix(diff);
+    Point transformed_from = transformation_matrix.apply(from);
+    Point transformed_to = transformation_matrix.apply(to);
+
+    PolygonsPointIndex result;
+
+    std::function<bool (const PolygonsPointIndex&)> process_elem_func =
+        [transformed_from, transformed_to, &transformation_matrix, &result, &ret]
+        (const PolygonsPointIndex& line_start)
+        {
+            Point p0 = transformation_matrix.apply(line_start.p());
+            Point p1 = transformation_matrix.apply(line_start.next().p());
+
+            if (LinearAlg2D::lineSegmentsCollide(transformed_from, transformed_to, p0, p1))
+            {
+                result = line_start;
+                ret = true;
+                return false;
+            }
+            return true;
+        };
+    loc_to_line.processLine(std::make_pair(from, to), process_elem_func);
+
+    if (collision_result)
+    {
+        *collision_result = result;
+    }
+    return ret;
+}
+
+bool PolygonUtils::polygonCollidesWithLineSegment(const PolygonRef poly, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix)
 {
     Point p0 = transformation_matrix.apply(poly.back());
     for(Point p1_ : poly)
     {
         Point p1 = transformation_matrix.apply(p1_);
-        if ((p0.Y >= transformed_startPoint.Y && p1.Y <= transformed_startPoint.Y) || (p1.Y >= transformed_startPoint.Y && p0.Y <= transformed_startPoint.Y))
+        if (LinearAlg2D::lineSegmentsCollide(transformed_startPoint, transformed_endPoint, p0, p1))
         {
-            int64_t x;
-            if(p1.Y == p0.Y)
-            {
-                x = p0.X;
-            }
-            else
-            {
-                x = p0.X + (p1.X - p0.X) * (transformed_startPoint.Y - p0.Y) / (p1.Y - p0.Y);
-            }
-            
-            if (x >= transformed_startPoint.X && x <= transformed_endPoint.X)
-                return true;
+            return true;
         }
         p0 = p1;
     }
     return false;
 }
 
-bool PolygonUtils::polygonCollidesWithlineSegment(const PolygonRef poly, Point& startPoint, Point& endPoint)
+bool PolygonUtils::polygonCollidesWithLineSegment(const PolygonRef poly, Point& startPoint, Point& endPoint)
 {
     Point diff = endPoint - startPoint;
 
@@ -877,15 +955,15 @@ bool PolygonUtils::polygonCollidesWithlineSegment(const PolygonRef poly, Point&
     Point transformed_startPoint = transformation_matrix.apply(startPoint);
     Point transformed_endPoint = transformation_matrix.apply(endPoint);
 
-    return PolygonUtils::polygonCollidesWithlineSegment(poly, transformed_startPoint, transformed_endPoint, transformation_matrix);
+    return PolygonUtils::polygonCollidesWithLineSegment(poly, transformed_startPoint, transformed_endPoint, transformation_matrix);
 }
 
-bool PolygonUtils::polygonCollidesWithlineSegment(const Polygons& polys, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix)
+bool PolygonUtils::polygonCollidesWithLineSegment(const Polygons& polys, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix)
 {
     for (const PolygonRef poly : const_cast<Polygons&>(polys))
     {
         if (poly.size() == 0) { continue; }
-        if (PolygonUtils::polygonCollidesWithlineSegment(poly, transformed_startPoint, transformed_endPoint, transformation_matrix))
+        if (PolygonUtils::polygonCollidesWithLineSegment(poly, transformed_startPoint, transformed_endPoint, transformation_matrix))
         {
             return true;
         }
@@ -895,7 +973,7 @@ bool PolygonUtils::polygonCollidesWithlineSegment(const Polygons& polys, Point&
 }
 
 
-bool PolygonUtils::polygonCollidesWithlineSegment(const Polygons& polys, Point& startPoint, Point& endPoint)
+bool PolygonUtils::polygonCollidesWithLineSegment(const Polygons& polys, Point& startPoint, Point& endPoint)
 {
     Point diff = endPoint - startPoint;
 
@@ -903,7 +981,7 @@ bool PolygonUtils::polygonCollidesWithlineSegment(const Polygons& polys, Point&
     Point transformed_startPoint = transformation_matrix.apply(startPoint);
     Point transformed_endPoint = transformation_matrix.apply(endPoint);
 
-    return polygonCollidesWithlineSegment(polys, transformed_startPoint, transformed_endPoint, transformation_matrix);
+    return polygonCollidesWithLineSegment(polys, transformed_startPoint, transformed_endPoint, transformation_matrix);
 }
 
 

src/utils/polygonUtils.h

@@ -20,16 +20,21 @@ namespace cura
 struct ClosestPolygonPoint
 {
     Point location; //!< Result location
-    PolygonRef poly; //!< Polygon in which the result was found
+    std::optional<PolygonRef> poly; //!< Polygon in which the result was found (or none if no result was found)
     unsigned int poly_idx; //!< The index of the polygon in some Polygons where ClosestPolygonPoint::poly can be found
     unsigned int point_idx; //!< Index to the first point in the polygon of the line segment on which the result was found
-    ClosestPolygonPoint(Point p, int pos, PolygonRef poly) :  location(p), poly(poly), poly_idx(NO_INDEX), point_idx(pos) {};
-    ClosestPolygonPoint(Point p, int pos, PolygonRef poly, int poly_idx) :  location(p), poly(poly), poly_idx(poly_idx), point_idx(pos) {};
-    ClosestPolygonPoint(PolygonRef poly) : poly(poly), poly_idx(NO_INDEX), point_idx(NO_INDEX) {};
+    ClosestPolygonPoint(Point p, int pos, PolygonRef poly) :  location(p), poly(true, poly), poly_idx(NO_INDEX), point_idx(pos) {};
+    ClosestPolygonPoint(Point p, int pos, PolygonRef poly, int poly_idx) :  location(p), poly(true, poly), poly_idx(poly_idx), point_idx(pos) {};
+    ClosestPolygonPoint(PolygonRef poly) : poly(true, poly), poly_idx(NO_INDEX), point_idx(NO_INDEX) {};
+    ClosestPolygonPoint() : poly_idx(NO_INDEX), point_idx(NO_INDEX) {};
     Point p() const
     { // conformity with other classes
         return location;
     }
+    bool isValid() const
+    {
+        return point_idx != NO_INDEX;
+    }
 };
 
 /*!
@@ -56,6 +61,8 @@ struct PolygonsPointIndexSegmentLocator
     }
 };
 
+typedef SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator> LocToLineGrid;
+
 class PolygonUtils 
 {
 public:
@@ -137,13 +144,20 @@ public:
      * When the point is already in/outside by more than \p distance, \p from is unaltered, but the polygon is returned.
      * When the point is in/outside by less than \p distance, \p from is moved to the correct place.
      * 
+     * \warning If \p loc_to_line_grid is used, it's best to have all and only \p polygons in there.
+     * If \p from is not closest to \p polygons this function may
+     * return a ClosestPolygonPoint on a polygon in \p loc_to_line_grid which is not in \p polygons.
+     * 
      * \param polygons The polygons onto which to move the point
      * \param from[in,out] The point to move.
      * \param distance The distance by which to move the point.
      * \param max_dist2 The squared maximal allowed distance from the point to the nearest polygon.
+     * \param loc_to_line_polygons All polygons with which the \p loc_to_line_grid has been created.
+     * \param loc_to_line_grid A SparseGrid mapping locations to line segments of \p polygons
+     * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
      * \return The point on the polygon closest to \p from
      */
-    static ClosestPolygonPoint moveInside2(const Polygons& polygons, Point& from, const int distance = 0, const int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static ClosestPolygonPoint moveInside2(const Polygons& polygons, Point& from, const int distance = 0, const int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const Polygons* loc_to_line_polygons = nullptr, const LocToLineGrid* loc_to_line_grid = nullptr, const std::function<int(Point)>& penalty_function = no_penalty_function);
 
     /*!
      * Moves the point \p from onto the nearest segment of \p polygon or leaves the point as-is, when the comb boundary is not within the root of \p max_dist2 distance.
@@ -151,14 +165,20 @@ public:
      * When the point is already in/outside by more than \p distance, \p from is unaltered, but the polygon is returned.
      * When the point is in/outside by less than \p distance, \p from is moved to the correct place.
      * 
+     * \warning When a \p loc_to_line is given this function only considers nearby elements.
+     * Even when the penalty function favours elements farther away.
+     * Also using the \p loc_to_line_grid automatically considers \p all_polygons
+     * 
+     * \param loc_to_line_polygons All polygons which are present in the \p loc_to_line_grid of which \p polygon is an element
      * \param polygon The polygon onto which to move the point
      * \param from[in,out] The point to move.
      * \param distance The distance by which to move the point.
      * \param max_dist2 The squared maximal allowed distance from the point to the nearest polygon.
+     * \param loc_to_line_grid A SparseGrid mapping locations to line segments of \p polygon
      * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
      * \return The point on the polygon closest to \p from
      */
-    static ClosestPolygonPoint moveInside2(const PolygonRef polygon, Point& from, const int distance = 0, const int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static ClosestPolygonPoint moveInside2(const Polygons& loc_to_line_polygons, const PolygonRef polygon, Point& from, const int distance = 0, const int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const LocToLineGrid* loc_to_line_grid = nullptr, const std::function<int(Point)>& penalty_function = no_penalty_function);
 
     /*!
      * The opposite of moveInside.
@@ -210,14 +230,45 @@ public:
      * but it might still be the case that we end up outside:
      * when the closest point on the boundary is very close to another polygon
      * 
+     * \warning When using a \p loc_to_line_grid which contains more polygons than just \p polygons,
+     * the results is only correct if \p from is already closest to \p polygons, rather than other polygons in the \p loc_to_line_grid.
+     * 
      * \param polygons The polygons onto which to move the point
      * \param from[in,out] The point to move.
      * \param preferred_dist_inside The preferred distance from the boundary to the point
      * \param max_dist2 The squared maximal allowed distance from the point to the nearest polygon.
+     * \param loc_to_line_polygons The original polygons with which the \p loc_to_line_grid has been created
+     * \param loc_to_line_grid A SparseGrid mapping locations to line segments of \p polygons
      * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
      * \return The point on the polygon closest to \p from
      */
-    static ClosestPolygonPoint ensureInsideOrOutside(const Polygons& polygons, Point& from, int preferred_dist_inside, int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static ClosestPolygonPoint ensureInsideOrOutside(const Polygons& polygons, Point& from, int preferred_dist_inside, int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const Polygons* loc_to_line_polygons = nullptr, const LocToLineGrid* loc_to_line_grid = nullptr, const std::function<int(Point)>& penalty_function = no_penalty_function);
+
+    /*!
+     * Moves the point \p from onto the nearest polygon or leaves the point as-is, when the comb boundary is not within \p distance.
+     * Given a \p distance more than zero, the point will end up inside, and conversely outside.
+     * When the point is already in/outside by more than \p distance, \p from is unaltered, but the polygon is returned.
+     * When the point is in/outside by less than \p distance, \p from is moved to the correct place.
+     * 
+     * \warning May give false positives.
+     * Some checking is done to make sure we end up inside the polygon, 
+     * but it might still be the case that we end up outside:
+     * when the closest point on the boundary is very close to another polygon
+     * 
+     * \warning When using a \p loc_to_line_grid which contains more polygons than just \p polygons,
+     * the results is only correct if \p from is already closest to \p polygons, rather than other polygons in the \p loc_to_line_grid.
+     * 
+     * \param polygons The polygons onto which to move the point
+     * \param from[in,out] The point to move.
+     * \param closest_polygon_point The point on \p polygons closest to \p from
+     * \param preferred_dist_inside The preferred distance from the boundary to the point
+     * \param max_dist2 The squared maximal allowed distance from the point to the nearest polygon.
+     * \param loc_to_line_polygons The original polygons with which the \p loc_to_line_grid has been created
+     * \param loc_to_line_grid A SparseGrid mapping locations to line segments of \p polygons
+     * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
+     * \return The point on the polygon closest to \p from
+     */
+    static ClosestPolygonPoint ensureInsideOrOutside(const Polygons& polygons, Point& from, ClosestPolygonPoint& closest_polygon_point, int preferred_dist_inside, int64_t max_dist2 = std::numeric_limits<int64_t>::max(), const Polygons* loc_to_line_polygons = nullptr, const LocToLineGrid* loc_to_line_grid = nullptr, const std::function<int(Point)>& penalty_function = no_penalty_function);
 
     /*!
     * Find the two points in two polygons with the smallest distance.
@@ -303,7 +354,7 @@ public:
      * \param square_size The cell size used to bundle line segments (also used to chop up lines so that multiple cells contain the same long line)
      * \return A bucket grid mapping spatial locations to poly-point indices into \p polygons
      */
-    static SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>* createLocToLineGrid(const Polygons& polygons, int square_size);
+    static LocToLineGrid* createLocToLineGrid(const Polygons& polygons, int square_size);
 
     /*!
      * Find the line segment closest to a given point \p from within a cell-block of a size defined in the SparsePointGridInclusive \p loc_to_line
@@ -317,7 +368,7 @@ public:
      * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
      * \return The nearest point on the polygon if the polygon was within a distance equal to the cell_size of the SparsePointGridInclusive
      */
-    static std::optional<ClosestPolygonPoint> findClose(Point from, const Polygons& polygons, const SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>& loc_to_line, const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static std::optional<ClosestPolygonPoint> findClose(Point from, const Polygons& polygons, const LocToLineGrid& loc_to_line, const std::function<int(Point)>& penalty_function = no_penalty_function);
 
     /*!
      * Find the line segment closest to any point on \p from within cell-blocks of a size defined in the SparsePointGridInclusive \p destination_loc_to_line
@@ -331,7 +382,23 @@ public:
      * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
      * \return A collection of near crossing from the \p from polygon to the \p destination polygon. Each element in the sollection is a pair with as first a cpp in the \p from polygon and as second a cpp in the \p destination polygon.
      */
-    static std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> findClose(const PolygonRef from, const Polygons& destination, const SparseLineGrid<PolygonsPointIndex, PolygonsPointIndexSegmentLocator>& destination_loc_to_line, const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> findClose(const PolygonRef from, const Polygons& destination, const LocToLineGrid& destination_loc_to_line, const std::function<int(Point)>& penalty_function = no_penalty_function);
+
+    /*!
+     * Checks whether a given line segment collides with polygons as given in a loc_to_line grid.
+     * 
+     * If the line segment doesn't intersect with any edge of the polygon, but
+     * merely touches it, a collision is also reported. For instance, a
+     * collision is reported when the an endpoint of the line is exactly on the
+     * polygon, and when the line coincides with an edge.
+     * 
+     * \param[in] from The start point
+     * \param[in] to The end point
+     * \param[in] loc_to_line A SparsePointGridInclusive mapping locations to starting vertices of line segmetns of the \p polygons 
+     * \param[out] collision_result (optional) The polygons segment intersecting with the line segment
+     * \return whether the line segment collides with the boundary of the polygons
+     */
+    static bool polygonCollidesWithLineSegment(const Point from, const Point to, const LocToLineGrid& loc_to_line, PolygonsPointIndex* collision_result = nullptr);
 
     /*!
     * Find the next point (going along the direction of the polygon) with a distance \p dist from the point \p from within the \p poly.
@@ -366,7 +433,7 @@ public:
      * \return whether the line segment collides with the boundary of the
      * polygon(s)
      */
-    static bool polygonCollidesWithlineSegment(const PolygonRef poly, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix);
+    static bool polygonCollidesWithLineSegment(const PolygonRef poly, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix);
 
     /*!
      * Checks whether a given line segment collides with a given polygon(s).
@@ -382,7 +449,7 @@ public:
      * \return whether the line segment collides with the boundary of the
      * polygon(s)
      */
-    static bool polygonCollidesWithlineSegment(const PolygonRef poly, Point& startPoint, Point& endPoint);
+    static bool polygonCollidesWithLineSegment(const PolygonRef poly, Point& startPoint, Point& endPoint);
 
     /*!
      * Checks whether a given line segment collides with a given polygon(s).
@@ -404,7 +471,7 @@ public:
      * \return whether the line segment collides with the boundary of the
      * polygon(s)
      */
-    static bool polygonCollidesWithlineSegment(const Polygons& polys, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix);
+    static bool polygonCollidesWithLineSegment(const Polygons& polys, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix);
 
     /*!
      * Checks whether a given line segment collides with a given polygon(s).
@@ -420,7 +487,7 @@ public:
      * \return whether the line segment collides with the boundary of the
      * polygon(s)
      */
-    static bool polygonCollidesWithlineSegment(const Polygons& polys, Point& startPoint, Point& endPoint);
+    static bool polygonCollidesWithLineSegment(const Polygons& polys, Point& startPoint, Point& endPoint);
 
 private:
     /*!

src/utils/string.h

@@ -5,6 +5,10 @@
 #include <cstdio> // sprintf
 #include <sstream> // ostringstream
 
+#include <cinttypes> // PRId64
+
+#include "logoutput.h"
+
 namespace cura
 {
     
@@ -29,8 +33,19 @@ static inline int stringcasecompare(const char* a, const char* b)
  */
 static inline void writeInt2mm(const int64_t coord, std::ostream& ss)
 {
-    char buffer[24];
-    int char_count = sprintf(buffer, "%ld", coord); // convert int to string
+    constexpr size_t buffer_size = 24;
+    char buffer[buffer_size];
+    int char_count = sprintf(buffer, "%" PRId64, coord); // convert int to string
+#ifdef DEBUG
+    if (char_count + 1 >= int(buffer_size)) // + 1 for the null character
+    {
+        logError("Cannot write %ld to buffer of size %i", coord, buffer_size);
+    }
+    if (char_count < 0)
+    {
+        logError("Encoding error while writing %ld", coord);
+    }
+#endif // DEBUG
     int end_pos = char_count; // the first character not to write any more
     int trailing_zeros = 1;
     while (trailing_zeros < 4 && buffer[char_count - trailing_zeros] == '0')
@@ -53,7 +68,7 @@ static inline void writeInt2mm(const int64_t coord, std::ostream& ss)
             ss << '-';
             start = 1;
         }
-        ss << '.';
+        ss << "0.";
         for (int nulls = char_count - start; nulls < 3; nulls++)
         { // fill up to 3 decimals with zeros
             ss << '0';
@@ -103,10 +118,21 @@ struct MMtoStream
  */
 static inline void writeDoubleToStream(const unsigned int precision, const double coord, std::ostream& ss)
 {
-    char format[5] = "%.xf"; // write a float with [x] digits after the dot
+    char format[5] = "%.xF"; // write a float with [x] digits after the dot
     format[2] = '0' + precision; // set [x]
-    char buffer[24];
-    int char_count = snprintf(buffer, 24, format, coord);
+    constexpr size_t buffer_size = 400;
+    char buffer[buffer_size];
+    int char_count = sprintf(buffer, format, coord);
+#ifdef DEBUG
+    if (char_count + 1 >= int(buffer_size)) // + 1 for the null character
+    {
+        logError("Cannot write %f to buffer of size %i", coord, buffer_size);
+    }
+    if (char_count < 0)
+    {
+        logError("Encoding error while writing %f", coord);
+    }
+#endif // DEBUG
     if (char_count <= 0)
     {
         return;

tests/utils/PolygonTest.cpp

@@ -91,6 +91,27 @@ void PolygonTest::isOutsideTest()
     CPPUNIT_ASSERT_MESSAGE("Below point is calculated as inside while it's outside!", !test_triangle.inside(Point(100, -100)));
 }
 
+void PolygonTest::isInsideTest()
+{
+    Polygons test_polys;
+    PolygonRef poly = test_polys.newPoly();
+    poly.add(Point(82124,98235));
+    poly.add(Point(83179,98691));
+    poly.add(Point(83434,98950));
+    poly.add(Point(82751,99026));
+    poly.add(Point(82528,99019));
+    poly.add(Point(81605,98854));
+    poly.add(Point(80401,98686));
+    poly.add(Point(79191,98595));
+    poly.add(Point(78191,98441));
+    poly.add(Point(78998,98299));
+    poly.add(Point(79747,98179));
+    poly.add(Point(80960,98095));
+
+    CPPUNIT_ASSERT_MESSAGE("Inside point is calculated as being outside!", test_polys.inside(Point(78315, 98440)));
+
+}
+
 
 
 

tests/utils/PolygonTest.h

@@ -21,6 +21,7 @@ class PolygonTest : public CppUnit::TestFixture
     CPPUNIT_TEST(polygonOffsetTest);
     CPPUNIT_TEST(polygonOffsetBugTest);
     CPPUNIT_TEST(isOutsideTest);
+    CPPUNIT_TEST(isInsideTest);
     CPPUNIT_TEST_SUITE_END();
 
 public:
@@ -44,6 +45,7 @@ public:
     void polygonOffsetTest();
     void polygonOffsetBugTest();
     void isOutsideTest();
+    void isInsideTest();
 
 
 private:

tests/utils/StringTest.cpp

@@ -3,10 +3,12 @@
 
 #include "StringTest.h"
 
+#include <iomanip>
 #include <sstream> // ostringstream
 #include <../src/utils/intpoint.h>
 #include <../src/utils/string.h>
 
+
 namespace cura
 {
     CPPUNIT_TEST_SUITE_REGISTRATION(StringTest);
@@ -69,13 +71,25 @@ void StringTest::writeInt2mmTest123456789()
 {
     writeInt2mmAssert(123456789);
 }
+void StringTest::writeInt2mmTestMax()
+{
+    writeInt2mmAssert(std::numeric_limits<int64_t>::max() / 1001); // divide by 1001, because MM2INT first converts to int and then multiplies by 1000, which causes overflow for the highest integer.
+}
 
 
 void StringTest::writeInt2mmAssert(int64_t in)
 {
     std::ostringstream ss;
     writeInt2mm(in, ss);
+
+    ss.flush();
     std::string str = ss.str();
+    if (!ss.good())
+    {
+        char buffer[200];
+        sprintf(buffer, "The integer %ld was printed as '%s' which was a bad string!", in, str.c_str());
+        CPPUNIT_ASSERT_MESSAGE(std::string(buffer), false);
+    }
     int64_t out = MM2INT(strtod(str.c_str(), nullptr));
 
     char buffer[200];
@@ -84,4 +98,102 @@ void StringTest::writeInt2mmAssert(int64_t in)
 }
 
 
+void StringTest::writeDoubleToStreamTest10000Negative()
+{
+    writeDoubleToStreamAssert(-10.000);
+}
+void StringTest::writeDoubleToStreamTest1000Negative()
+{
+    writeDoubleToStreamAssert(-1.000);
+}
+void StringTest::writeDoubleToStreamTest100Negative()
+{
+    writeDoubleToStreamAssert(-.100);
+}
+void StringTest::writeDoubleToStreamTest10Negative()
+{
+    writeDoubleToStreamAssert(-.010);
+}
+void StringTest::writeDoubleToStreamTest1Negative()
+{
+    writeDoubleToStreamAssert(-.001);
+}
+void StringTest::writeDoubleToStreamTest0()
+{
+    writeDoubleToStreamAssert(0.000);
+}
+void StringTest::writeDoubleToStreamTest1()
+{
+    writeDoubleToStreamAssert(.001);
+}
+void StringTest::writeDoubleToStreamTest10()
+{
+    writeDoubleToStreamAssert(.010);
+}
+void StringTest::writeDoubleToStreamTest100()
+{
+    writeDoubleToStreamAssert(.100);
+}
+void StringTest::writeDoubleToStreamTest1000()
+{
+    writeDoubleToStreamAssert(1.000);
+}
+void StringTest::writeDoubleToStreamTest10000()
+{
+    writeDoubleToStreamAssert(10.000);
+}
+void StringTest::writeDoubleToStreamTest123456789()
+{
+    writeDoubleToStreamAssert(123456.789);
+}
+
+
+void StringTest::writeDoubleToStreamTestMin()
+{
+    writeDoubleToStreamAssert(std::numeric_limits<double>::min());
+}
+void StringTest::writeDoubleToStreamTestMax()
+{
+    writeDoubleToStreamAssert(std::numeric_limits<double>::max());
+}
+void StringTest::writeDoubleToStreamTestLowest()
+{
+    writeDoubleToStreamAssert(std::numeric_limits<double>::lowest());
+}
+void StringTest::writeDoubleToStreamTestLowestNeg()
+{
+    writeDoubleToStreamAssert(-std::numeric_limits<double>::lowest());
+}
+void StringTest::writeDoubleToStreamTestLow()
+{
+    writeDoubleToStreamAssert(0.00000001d);
+}
+
+
+void StringTest::writeDoubleToStreamAssert(double in, unsigned int precision)
+{
+    std::ostringstream ss;
+    writeDoubleToStream(precision, in, ss);
+    ss.flush();
+    std::string str = ss.str();
+    if (!ss.good())
+    {
+        char buffer[8000];
+        sprintf(buffer, "The double %f was printed as '%s' which was a bad string!", in, str.c_str());
+        CPPUNIT_ASSERT_MESSAGE(std::string(buffer), false);
+    }
+    double out = strtod(str.c_str(), nullptr);
+
+    std::ostringstream in_ss;
+    in_ss << std::fixed << std::setprecision(precision) << in;
+    std::string in_str = in_ss.str();
+    double in_reinterpreted = strtod(in_str.c_str(), nullptr);
+    
+    char buffer[8000];
+    sprintf(buffer, "The double %f was printed as '%s' which was interpreted as %f rather than %f!", in, str.c_str(), out, in_reinterpreted);
+    if (in_reinterpreted != out) std::cerr << buffer << "\n";
+    CPPUNIT_ASSERT_MESSAGE(std::string(buffer), in_reinterpreted == out);
+}
+
+
 }

tests/utils/StringTest.h

@@ -25,6 +25,25 @@ class StringTest : public CppUnit::TestFixture
     CPPUNIT_TEST(writeInt2mmTest1000);
     CPPUNIT_TEST(writeInt2mmTest10000);
     CPPUNIT_TEST(writeInt2mmTest123456789);
+    CPPUNIT_TEST(writeInt2mmTestMax);
+
+    CPPUNIT_TEST(writeDoubleToStreamTest10000Negative);
+    CPPUNIT_TEST(writeDoubleToStreamTest1000Negative);
+    CPPUNIT_TEST(writeDoubleToStreamTest100Negative);
+    CPPUNIT_TEST(writeDoubleToStreamTest10Negative);
+    CPPUNIT_TEST(writeDoubleToStreamTest1Negative);
+    CPPUNIT_TEST(writeDoubleToStreamTest0);
+    CPPUNIT_TEST(writeDoubleToStreamTest1);
+    CPPUNIT_TEST(writeDoubleToStreamTest10);
+    CPPUNIT_TEST(writeDoubleToStreamTest100);
+    CPPUNIT_TEST(writeDoubleToStreamTest1000);
+    CPPUNIT_TEST(writeDoubleToStreamTest10000);
+    CPPUNIT_TEST(writeDoubleToStreamTest123456789);
+    CPPUNIT_TEST(writeDoubleToStreamTestMin);
+    CPPUNIT_TEST(writeDoubleToStreamTestMax);
+    CPPUNIT_TEST(writeDoubleToStreamTestLowest);
+    CPPUNIT_TEST(writeDoubleToStreamTestLowestNeg);
+    CPPUNIT_TEST(writeDoubleToStreamTestLow);
     CPPUNIT_TEST_SUITE_END();
 
 public:
@@ -57,6 +76,25 @@ public:
     void writeInt2mmTest1000();
     void writeInt2mmTest10000();
     void writeInt2mmTest123456789();
+    void writeInt2mmTestMax();
+
+    void writeDoubleToStreamTest10000Negative();
+    void writeDoubleToStreamTest1000Negative();
+    void writeDoubleToStreamTest100Negative();
+    void writeDoubleToStreamTest10Negative();
+    void writeDoubleToStreamTest1Negative();
+    void writeDoubleToStreamTest0();
+    void writeDoubleToStreamTest1();
+    void writeDoubleToStreamTest10();
+    void writeDoubleToStreamTest100();
+    void writeDoubleToStreamTest1000();
+    void writeDoubleToStreamTest10000();
+    void writeDoubleToStreamTest123456789();
+    void writeDoubleToStreamTestMin();
+    void writeDoubleToStreamTestMax();
+    void writeDoubleToStreamTestLowest();
+    void writeDoubleToStreamTestLowestNeg();
+    void writeDoubleToStreamTestLow();
 
 private:
 
@@ -69,6 +107,17 @@ private:
      * \param in the integer to check
      */
     void writeInt2mmAssert(int64_t in);
+
+    /*!
+     * \brief Performs the actual assertion for the getDist2FromLineSegmentTest.
+     * 
+     * This is essentially a parameterised version of all unit tests pertaining
+     * to the writeInt2mm tests.
+     * 
+     * \param in the double to check
+     * \param precision the (maximum) number of digits after the decimal mark to print
+     */
+    void writeDoubleToStreamAssert(double in, unsigned int precision = 4);
 };
 
 }