fix: handle multithreaded progress messages (CURA-781)

CURA-541

CMakeLists.txt

@@ -42,6 +42,16 @@ if(NOT APPLE AND NOT WIN32)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static-libstdc++")
 endif()
 
+option (ENABLE_OPENMP
+    "Use OpenMP for parallel code" ON)
+
+if (ENABLE_OPENMP)
+    FIND_PACKAGE( OpenMP )
+    if( OPENMP_FOUND )
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}" )
+    endif()
+endif()
+
 include_directories(${CMAKE_CURRENT_BINARY_DIR} libs)
 
 add_library(clipper STATIC libs/clipper/clipper.cpp)
@@ -79,15 +89,20 @@ set(engine_SRCS # Except main.cpp.
     src/wallOverlap.cpp
     src/Weaver.cpp
     src/Wireframe2gcode.cpp
+    src/multithreadOpenMP.cpp
 
     src/infill/NoZigZagConnectorProcessor.cpp
     src/infill/ZigzagConnectorProcessorConnectedEndPieces.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

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  

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
     {
@@ -80,9 +82,24 @@ void FffGcodeWriter::writeGCode(SliceDataStorage& storage, TimeKeeper& time_keep
         }
     }
 
-    for(unsigned int layer_nr=0; layer_nr<total_layers; layer_nr++)
+    { // 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));
+        }
+    }
+
+#pragma omp parallel default(none) shared(storage, total_layers)
     {
-        processLayer(storage, layer_nr, total_layers);
+#pragma omp single nowait
+        {
+            for(unsigned int layer_nr=0; layer_nr<total_layers; layer_nr++)
+            {
+                processLayer(storage, layer_nr, total_layers);
+            }
+        }
     }
     
     Progress::messageProgressStage(Progress::Stage::FINISH, &time_keeper);
@@ -93,7 +110,7 @@ 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)
@@ -183,7 +200,10 @@ void FffGcodeWriter::initConfigs(SliceDataStorage& storage)
         mesh.inset0_config.init(mesh.getSettingInMillimetersPerSecond("speed_wall_0"), mesh.getSettingInMillimetersPerSecond("acceleration_wall_0"), mesh.getSettingInMillimetersPerSecond("jerk_wall_0"), mesh.getSettingInMicrons("wall_line_width_0"), mesh.getSettingInPercentage("material_flow"));
         mesh.insetX_config.init(mesh.getSettingInMillimetersPerSecond("speed_wall_x"), mesh.getSettingInMillimetersPerSecond("acceleration_wall_x"), mesh.getSettingInMillimetersPerSecond("jerk_wall_x"), mesh.getSettingInMicrons("wall_line_width_x"), mesh.getSettingInPercentage("material_flow"));
         mesh.skin_config.init(mesh.getSettingInMillimetersPerSecond("speed_topbottom"), mesh.getSettingInMillimetersPerSecond("acceleration_topbottom"), mesh.getSettingInMillimetersPerSecond("jerk_topbottom"), mesh.getSettingInMicrons("skin_line_width"), mesh.getSettingInPercentage("material_flow"));
-    
+        mesh.perimeter_gap_config.init(mesh.getSettingInMillimetersPerSecond("speed_topbottom"), mesh.getSettingInMillimetersPerSecond("acceleration_topbottom"), mesh.getSettingInMillimetersPerSecond("jerk_topbottom"), mesh.getSettingInMicrons("wall_line_width_x") / 2, mesh.getSettingInPercentage("material_flow"));
+        //  the perimeter gap config follows the skin config, but has a different line width:
+        // wall_line_width_x divided by two because the gaps are between 0 and 1 times the wall line width
+
         for (unsigned int idx = 0; idx < MAX_INFILL_COMBINE; idx++)
         {
             mesh.infill_config[idx].init(mesh.getSettingInMillimetersPerSecond("speed_infill"), mesh.getSettingInMillimetersPerSecond("acceleration_infill"), mesh.getSettingInMillimetersPerSecond("jerk_infill"), mesh.getSettingInMicrons("infill_line_width") * (idx + 1), mesh.getSettingInPercentage("material_flow"));
@@ -193,7 +213,26 @@ 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())
     {
@@ -201,15 +240,13 @@ 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_layer_0") > 0)
+            if (getSettingBoolean("machine_heated_bed") && getSettingInDegreeCelsius("material_bed_temperature_layer_0") != 0)
             {
                 gcode.writeBedTemperatureCommand(getSettingInDegreeCelsius("material_bed_temperature_layer_0"), getSettingBoolean("material_bed_temp_wait"));
             }
@@ -257,8 +294,9 @@ void FffGcodeWriter::processStartingCode(SliceDataStorage& storage)
         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);
     }
 }
 
@@ -312,12 +350,14 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         int layer_height = train->getSettingInMicrons("raft_base_thickness");
         z += layer_height;
         int64_t comb_offset = train->getSettingInMicrons("raft_base_line_spacing");
-        GCodePlanner& gcode_layer = layer_plan_buffer.emplace_back(storage, layer_nr, z, layer_height, last_position_planned, current_extruder_planned, fan_speed_layer_time_settings_per_extruder, combing_mode, comb_offset, train->getSettingBoolean("travel_avoid_other_parts"), train->getSettingInMicrons("travel_avoid_distance"));
+        GCodePlanner& gcode_layer = layer_plan_buffer.createPlanner(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"));
+        // There should be a synchronization construct to make sure the writegcode task is complete before trimBuffer is called
+#pragma omp taskwait
+        layer_plan_buffer.trimBuffer();
+        gcode_layer.setIsInside(true);
+
+        gcode_layer.setExtruder(extruder_nr);
 
-        if (getSettingAsIndex("adhesion_extruder_nr") > 0)
-        {
-            gcode_layer.setExtruder(extruder_nr);
-        }
         if (CommandSocket::isInstantiated())
         {
             CommandSocket::getInstance()->sendOptimizedLayerInfo(layer_nr, z, layer_height);
@@ -332,10 +372,14 @@ 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();
-
-        ensureAllExtrudersArePrimed(storage, gcode_layer, layer_nr);
+        is_inside_mesh_layer_part = gcode_layer.getIsInsideMesh();
 
         gcode_layer.processFanSpeedAndMinimalLayerTime();
         gcode_layer.overrideFanSpeeds(train->getSettingInPercentage("raft_base_fan_speed"));
@@ -346,13 +390,19 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         int layer_height = train->getSettingInMicrons("raft_interface_thickness");
         z += layer_height;
         int64_t comb_offset = train->getSettingInMicrons("raft_interface_line_spacing");
-        GCodePlanner& gcode_layer = layer_plan_buffer.emplace_back(storage, layer_nr, z, layer_height, last_position_planned, current_extruder_planned, fan_speed_layer_time_settings_per_extruder, combing_mode, comb_offset, train->getSettingBoolean("travel_avoid_other_parts"), train->getSettingInMicrons("travel_avoid_distance"));
+        GCodePlanner& gcode_layer = layer_plan_buffer.createPlanner(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"));
+        // There should be a synchronization construct to make sure the writegcode task is complete before trimBuffer is called
+#pragma omp taskwait
+        layer_plan_buffer.trimBuffer();
+        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;
@@ -362,6 +412,7 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         
         last_position_planned = gcode_layer.getLastPosition();
         current_extruder_planned = gcode_layer.getExtruder();
+        is_inside_mesh_layer_part = gcode_layer.getIsInsideMesh();
 
         gcode_layer.processFanSpeedAndMinimalLayerTime();
         gcode_layer.overrideFanSpeeds(train->getSettingInPercentage("raft_interface_fan_speed"));
@@ -374,7 +425,11 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
         const int layer_nr = initial_raft_layer_nr + 2 + raftSurfaceLayer - 1; // 2: 1 base layer, 1 interface layer
         z += layer_height;
         const int64_t comb_offset = train->getSettingInMicrons("raft_surface_line_spacing");
-        GCodePlanner& gcode_layer = layer_plan_buffer.emplace_back(storage, layer_nr, z, layer_height, last_position_planned, current_extruder_planned, fan_speed_layer_time_settings_per_extruder, combing_mode, comb_offset, train->getSettingBoolean("travel_avoid_other_parts"), train->getSettingInMicrons("travel_avoid_distance"));
+        GCodePlanner& gcode_layer = layer_plan_buffer.createPlanner(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"));
+        // There should be a synchronization construct to make sure the writegcode task is complete before trimBuffer is called
+#pragma omp taskwait
+        layer_plan_buffer.trimBuffer();
+        gcode_layer.setIsInside(true);
 
         if (CommandSocket::isInstantiated())
         {
@@ -390,7 +445,8 @@ void FffGcodeWriter::processRaft(SliceDataStorage& storage, unsigned int total_l
 
         last_position_planned = gcode_layer.getLastPosition();
         current_extruder_planned = gcode_layer.getExtruder();
-
+        is_inside_mesh_layer_part = gcode_layer.getIsInsideMesh();
+        
         gcode_layer.processFanSpeedAndMinimalLayerTime();
         gcode_layer.overrideFanSpeeds(train->getSettingInPercentage("raft_surface_fan_speed"));
     }
@@ -432,7 +488,7 @@ 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))
@@ -447,7 +503,7 @@ 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")); 
@@ -456,22 +512,26 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
 
 
 
-    GCodePlanner& gcode_layer = layer_plan_buffer.emplace_back(storage, layer_nr, z, layer_thickness, last_position_planned, current_extruder_planned, fan_speed_layer_time_settings_per_extruder, getSettingAsCombingMode("retraction_combing"), comb_offset_from_outlines, avoid_other_parts, avoid_distance);
+    GCodePlanner& gcode_layer = layer_plan_buffer.createPlanner(storage, layer_nr, z, layer_thickness, last_position_planned, current_extruder_planned, is_inside_mesh_layer_part, fan_speed_layer_time_settings_per_extruder, getSettingAsCombingMode("retraction_combing"), comb_offset_from_outlines, avoid_other_parts, avoid_distance);
 
     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);
         }
     }
+    if (include_helper_parts)
+    { // 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));
+    }
 
     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");
 
-    //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<int> extruder_order = calculateExtruderOrder(storage, gcode_layer.getExtruder());
     for (int extruder_nr : extruder_order)
     {
@@ -483,9 +543,36 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
 
         if (layer_nr >= 0)
         {
-            std::vector<unsigned int> mesh_order = calculateMeshOrder(storage, extruder_nr);
-            for (unsigned int mesh_idx : mesh_order)
+            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;
+                        }
+                    }
+                }
+            }
+
+            for (unsigned int mesh_iterator_idx = 0; mesh_iterator_idx < mesh_order.size(); mesh_iterator_idx++)
             {
+                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)
                 {
@@ -499,7 +586,7 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
         }
     }
 
-    if (include_helper_parts && layer_nr == 0)
+    if (layer_nr == 0 && getExtrudersNeedPrimeDuringFirstLayer())
     {
         ensureAllExtrudersArePrimed(storage, gcode_layer, layer_nr);
     }
@@ -513,17 +600,33 @@ void FffGcodeWriter::processLayer(SliceDataStorage& storage, int layer_nr, unsig
     
     last_position_planned = gcode_layer.getLastPosition();
     current_extruder_planned = gcode_layer.getExtruder();
-
+    is_inside_mesh_layer_part = gcode_layer.getIsInsideMesh();
+    // There should be a synchronization construct to make sure the writegcode task is complete before trimBuffer is called
+#pragma omp taskwait
+    layer_plan_buffer.trimBuffer();
     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 skirt for all extruders which haven't primed the skirt or brim yet.
+    // 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 (gcode.getExtruderIsUsed(extruder_nr) && !skirt_brim_is_processed[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);
         }
     }
@@ -541,7 +644,7 @@ void FffGcodeWriter::processSkirtBrim(SliceDataStorage& storage, GCodePlanner& g
     {
         return;
     }
-    gcode_layer.addTravel(skirt_brim.back().closestPointTo(gcode_layer.getLastPosition()));
+    gcode_layer.addTravel(PolygonRef{skirt_brim.back()}.closestPointTo(gcode_layer.getLastPosition()));
     gcode_layer.addPolygonsByOptimizer(skirt_brim, &storage.skirt_brim_config[extruder_nr]);
 }
 
@@ -606,19 +709,30 @@ std::vector<int> FffGcodeWriter::calculateExtruderOrder(SliceDataStorage& storag
 
 std::vector<unsigned int> FffGcodeWriter::calculateMeshOrder(SliceDataStorage& storage, int extruder_nr)
 {
-    std::vector<unsigned int> ret;
+    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)
         {
-            ret.push_back(mesh_idx);
+            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;
 }
 
-void FffGcodeWriter::addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr)
+void FffGcodeWriter::addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& storage, const SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr)
 {
     if (layer_nr > mesh->layer_nr_max_filled_layer)
     {
@@ -634,7 +748,7 @@ void FffGcodeWriter::addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& stora
 
     setExtruder_addPrime(storage, gcode_layer, layer_nr, mesh->getSettingAsIndex("extruder_nr"));
 
-    SliceLayer* layer = &mesh->layers[layer_nr];
+    const SliceLayer* layer = &mesh->layers[layer_nr];
 
 
     Polygons polygons;
@@ -644,17 +758,18 @@ 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->getSettingInMicrons("wall_0_wipe_dist"), 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);
 }
 
-void FffGcodeWriter::addMeshOpenPolyLinesToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr)
+void FffGcodeWriter::addMeshOpenPolyLinesToGCode(SliceDataStorage& storage, const SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr)
 {
-    SliceLayer* layer = &mesh->layers[layer_nr];
+    const SliceLayer* layer = &mesh->layers[layer_nr];
     
     Polygons lines;
-    for(PolygonRef polyline : layer->openPolyLines)
+    for(ConstPolygonRef polyline : layer->openPolyLines)
     {
         for(unsigned int point_idx = 1; point_idx<polyline.size(); point_idx++)
         {
@@ -668,7 +783,7 @@ void FffGcodeWriter::addMeshOpenPolyLinesToGCode(SliceDataStorage& storage, Slic
     
 }
 
-void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr)
+void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, const SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr)
 {
     if (layer_nr > mesh->layer_nr_max_filled_layer)
     {
@@ -682,7 +797,7 @@ void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshSto
         return;
     }
 
-    SliceLayer* layer = &mesh->layers[layer_nr];
+    const SliceLayer* layer = &mesh->layers[layer_nr];
 
     if (layer->parts.size() == 0)
     {
@@ -692,7 +807,7 @@ void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshSto
     if (mesh->getSettingAsCount("wall_line_count") > 0)
     { // don't switch extruder if there's nothing to print
         bool empty = true;
-        for (SliceLayerPart& part : layer->parts)
+        for (const SliceLayerPart& part : layer->parts)
         {
             if (part.insets.size() > 0)
             {
@@ -709,73 +824,23 @@ 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");
+    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_type);
+    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(&part); // 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, part);
-        }
-
-        gcode_layer.setIsInside(nullptr);
+        const SliceLayerPart& part = layer->parts[part_idx];
+        addMeshPartToGCode(storage, mesh, part, gcode_layer, layer_nr);
     }
     if (mesh->getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL)
     {
@@ -783,11 +848,69 @@ void FffGcodeWriter::addMeshLayerToGCode(SliceDataStorage& storage, SliceMeshSto
     }
 }
 
+void FffGcodeWriter::addMeshPartToGCode(SliceDataStorage& storage, const SliceMeshStorage* mesh, const 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 = 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"), (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 = (layer_nr == 0)?
+        mesh->getSettingAsFillMethod("top_bottom_pattern_0") :
+        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");
+    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);
+}
 
             
 
 
-void FffGcodeWriter::processMultiLayerInfill(GCodePlanner& gcode_layer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int infill_angle)
+void FffGcodeWriter::processMultiLayerInfill(GCodePlanner& gcode_layer, const SliceMeshStorage* mesh, const SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int infill_angle)
 {
     int64_t z = layer_nr * getSettingInMicrons("layer_height");
     if (infill_line_distance > 0)
@@ -810,7 +933,7 @@ void FffGcodeWriter::processMultiLayerInfill(GCodePlanner& gcode_layer, SliceMes
                 }
                 
                 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);
+                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);
@@ -818,7 +941,7 @@ void FffGcodeWriter::processMultiLayerInfill(GCodePlanner& gcode_layer, SliceMes
     }
 }
 
-void FffGcodeWriter::processSingleLayerInfill(GCodePlanner& gcode_layer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int infill_angle)
+void FffGcodeWriter::processSingleLayerInfill(GCodePlanner& gcode_layer, const SliceMeshStorage* mesh, const SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int infill_angle)
 {
     if (infill_line_distance == 0 || part.infill_area_per_combine_per_density[0].size() == 0)
     {
@@ -866,7 +989,7 @@ void FffGcodeWriter::processSingleLayerInfill(GCodePlanner& gcode_layer, SliceMe
             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);
-        infill_comp.generate(infill_polygons, infill_lines);
+        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)
@@ -879,7 +1002,7 @@ 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, const SliceMeshStorage* mesh, const 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");
@@ -894,7 +1017,9 @@ 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, mesh->getSettingInMicrons("wall_0_wipe_dist"), 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;
@@ -909,13 +1034,14 @@ void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage*
             {
                 if (!compensate_overlap_0)
                 {
-                    gcode_layer.addPolygonsByOptimizer(part.insets[0], &mesh->inset0_config, nullptr, z_seam_type, mesh->getSettingInMicrons("wall_0_wipe_dist"), 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];
+                    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, mesh->getSettingInMicrons("wall_0_wipe_dist"), 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
@@ -926,7 +1052,7 @@ void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage*
                 }
                 else
                 {
-                    Polygons& outer_wall = part.insets[processed_inset_number];
+                    Polygons outer_wall = part.insets[processed_inset_number];
                     WallOverlapComputation wall_overlap_computation(outer_wall, mesh->getSettingInMicrons("wall_line_width_x"));
                     gcode_layer.addPolygonsByOptimizer(outer_wall, &mesh->insetX_config, &wall_overlap_computation);
                 }
@@ -936,30 +1062,35 @@ 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, const SliceMeshStorage* mesh, const 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();
+    const unsigned int perimeter_gaps_line_width = mesh->perimeter_gap_config.getLineWidth();
 
     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;
+    bool fill_perimeter_gaps = mesh->getSettingAsFillPerimeterGapMode("fill_perimeter_gaps") != FillPerimeterGapMode::NOWHERE
+                            && !mesh->getSettingBoolean("magic_spiralize");
 
-    PathOrderOptimizer part_order_optimizer(gcode_layer.getLastPosition(), EZSeamType::SHORTEST);
+    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;
+        const 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];
+        const SkinPart& skin_part = part.skin_parts[ordered_skin_part_idx];
 
         Polygons skin_polygons;
         Polygons skin_lines;
         
-        EFillMethod pattern = mesh->getSettingAsFillMethod("top_bottom_pattern");
+        EFillMethod pattern = (layer_nr == 0)?
+            mesh->getSettingAsFillMethod("top_bottom_pattern_0") :
+            mesh->getSettingAsFillMethod("top_bottom_pattern");
         int bridge = -1;
         if (layer_nr > 0)
             bridge = bridgeAngle(skin_part.outline, &mesh->layers[layer_nr-1]);
@@ -971,11 +1102,11 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
 
         Polygons perimeter_gaps; // the perimeter gaps of the insets of this skin part
 
-        Polygons* inner_skin_outline = nullptr;
+        const Polygons* inner_skin_outline = nullptr;
         int offset_from_inner_skin_outline = 0;
         if (pattern != EFillMethod::CONCENTRIC)
         {
-            for (Polygons& skin_perimeter : skin_part.insets)
+            for (const Polygons& skin_perimeter : skin_part.insets)
             {
                 gcode_layer.addPolygonsByOptimizer(skin_perimeter, &mesh->insetX_config); // add polygons to gcode in inward order
             }
@@ -988,13 +1119,13 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
                 {
                     // 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 * 2);
+                    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_extra_offset);
+                        const Polygons inner = skin_part.insets[inset_idx].offset(mesh->insetX_config.getLineWidth() / 2);
                         perimeter_gaps.add(outer.difference(inner));
                     }
                 }
@@ -1011,13 +1142,6 @@ void FffGcodeWriter::processSkin(GCodePlanner& gcode_layer, SliceMeshStorage* me
         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)
@@ -1028,28 +1152,56 @@ 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 skin insets
+            Polygons gap_polygons; // will remain empty
+            Polygons gap_lines;
+            int offset = 0;
+            Infill infill_comp(EFillMethod::LINES, perimeter_gaps, offset, perimeter_gaps_line_width, perimeter_gaps_line_width, skin_overlap, skin_angle, z, extra_infill_shift);
+            infill_comp.generate(gap_polygons, gap_lines);
+            gcode_layer.addLinesByOptimizer(gap_lines, &mesh->perimeter_gap_config, 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 = 1; inset_idx < part.insets.size(); inset_idx++)
+        for (unsigned int inset_idx = 0; inset_idx < part.insets.size() - 1; inset_idx++)
         {
-            const Polygons outer = part.insets[inset_idx - 1].offset(-1 * line_width / 2 - perimeter_gaps_extra_offset);
+            const Polygons outer = part.insets[inset_idx].offset(-1 * line_width / 2 - perimeter_gaps_extra_offset);
             line_width = mesh->insetX_config.getLineWidth();
-            const Polygons inner = part.insets[inset_idx].offset(line_width / 2 + perimeter_gaps_extra_offset);
+
+            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")
+                && mesh->getSettingInMicrons("infill_overlap_mm") >= 0
+            )
+            {
+                const Polygons outer = part.insets.back().offset(-1 * line_width / 2 - perimeter_gaps_extra_offset);
 
-        Polygons skin_polygons; // unused
-        Polygons skin_lines; // soon to be generated gap filler lines
+                Polygons inner = part.infill_area;
+                for (const SkinPart& skin_part : part.skin_parts)
+                {
+                    inner.add(skin_part.outline);
+                }
+                inner = inner.unionPolygons();
+                perimeter_gaps.add(outer.difference(inner));
+            }
+        }
+
+        Polygons gap_polygons; // unused
+        Polygons gap_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);
+        Infill infill_comp(EFillMethod::LINES, perimeter_gaps, offset, perimeter_gaps_line_width, perimeter_gaps_line_width, skin_overlap, skin_angle, z, extra_infill_shift);
+        infill_comp.generate(gap_polygons, gap_lines);
 
-        gcode_layer.addLinesByOptimizer(skin_lines, &mesh->skin_config, SpaceFillType::Lines);
+        gcode_layer.addLinesByOptimizer(gap_lines, &mesh->perimeter_gap_config, SpaceFillType::Lines);
     }
 }
 
@@ -1110,7 +1262,7 @@ bool FffGcodeWriter::addSupportInfillToGCode(SliceDataStorage& storage, GCodePla
     PathOrderOptimizer island_order_optimizer(gcode_layer.getLastPosition());
     for(unsigned int n=0; n<support_islands.size(); n++)
     {
-        island_order_optimizer.addPolygon(support_islands[n][0]);
+        island_order_optimizer.addPolygon(PolygonRef{support_islands[n][0]});
     }
     island_order_optimizer.optimize();
 
@@ -1227,11 +1379,29 @@ 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);
         }
-        addPrimeTower(storage, gcode_layer, layer_nr, previous_extruder);
+        if (layer_nr >= -Raft::getFillerLayerCount(storage))
+        {
+            addPrimeTower(storage, gcode_layer, layer_nr, previous_extruder);
+        }
     }
 }
 

src/FffGcodeWriter.h

@@ -65,18 +65,28 @@ 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
     int current_extruder_planned; //!< The extruder train in use before planning the next layer
+    bool is_inside_mesh_layer_part; //!< Whether the last position was inside a layer part (used in combing)
 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;
     }
 
     /*!
@@ -173,15 +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.
@@ -210,6 +231,13 @@ private:
      */
     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.
@@ -273,7 +301,7 @@ private:
      * \param layer_nr The index of the layer to write the gcode of.
      * 
      */
-    void addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcodeLayer, int layer_nr);
+    void addMeshLayerToGCode_meshSurfaceMode(SliceDataStorage& storage, const SliceMeshStorage* mesh, GCodePlanner& gcodeLayer, int layer_nr);
     
     /*!
      * Add the open polylines from a single layer from a single mesh-volume to the layer plan \p gcodeLayer for mesh the surface modes.
@@ -284,18 +312,30 @@ private:
      * \param layer_nr The index of the layer to write the gcode of.
      * 
      */
-    void addMeshOpenPolyLinesToGCode(SliceDataStorage& storage, SliceMeshStorage* mesh, GCodePlanner& gcode_layer, int layer_nr);
+    void addMeshOpenPolyLinesToGCode(SliceDataStorage& storage, const 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, const 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, const SliceMeshStorage* mesh, const SliceLayerPart& part, GCodePlanner& gcode_layer, int layer_nr);
     
     /*!
      * Add thicker (multiple layers) sparse infill for a given part in a layer plan.
@@ -308,7 +348,7 @@ private:
      * \param infill_overlap The distance by which the infill overlaps with the wall insets.
      * \param fillAngle The angle in the XY plane at which the infill is generated.
      */
-    void processMultiLayerInfill(GCodePlanner& gcodeLayer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int fillAngle); 
+    void processMultiLayerInfill(GCodePlanner& gcodeLayer, const SliceMeshStorage* mesh, const SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int fillAngle);
     
     /*!
      * Add normal sparse infill for a given part in a layer.
@@ -320,7 +360,7 @@ private:
      * \param infill_overlap The distance by which the infill overlaps with the wall insets.
      * \param fillAngle The angle in the XY plane at which the infill is generated.
      */
-    void processSingleLayerInfill(GCodePlanner& gcodeLayer, SliceMeshStorage* mesh, SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int fillAngle);
+    void processSingleLayerInfill(GCodePlanner& gcodeLayer, const SliceMeshStorage* mesh, const SliceLayerPart& part, unsigned int layer_nr, int infill_line_distance, int infill_overlap, int fillAngle);
     
     /*!
      * Generate the insets for the walls of a given layer part.
@@ -329,20 +369,25 @@ 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, const SliceMeshStorage* mesh, const 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, const cura::SliceMeshStorage* mesh, const 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 for all support parts with the given \p extruder_nr.

src/FffPolygonGenerator.cpp

@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <map> // multimap (ordered map allowing duplicate keys)
+#include <omp.h>
 
 #include "utils/math.h"
 #include "utils/algorithm.h"
@@ -23,7 +24,7 @@
 #include "progress/ProgressEstimator.h"
 #include "progress/ProgressStageEstimator.h"
 #include "progress/ProgressEstimatorLinear.h"
-
+#include "multithreadOpenMP.h"
 
 namespace cura
 {
@@ -31,6 +32,17 @@ namespace cura
 
 bool FffPolygonGenerator::generateAreas(SliceDataStorage& storage, MeshGroup* meshgroup, TimeKeeper& timeKeeper)
 {
+#pragma omp parallel
+    {
+#pragma omp master
+        {
+#ifdef _OPENMP
+            log("OpenMP enabled, number of threads used: %u\n", omp_get_num_threads());
+#else
+            log("OpenMP disabled\n");
+#endif
+        }
+    }
     if (!sliceModel(meshgroup, timeKeeper, storage)) 
     {
         return false;
@@ -53,7 +65,7 @@ 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);
     }
 }
 
@@ -151,6 +163,10 @@ bool FffPolygonGenerator::sliceModel(MeshGroup* meshgroup, TimeKeeper& timeKeepe
                 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);
+                meshStorage.layers[layer_nr].printZ =
+                    slicer_layer.z
+                    + getSettingInMicrons("layer_height_0")
+                    - initial_slice_z;
             }
             continue;
         }
@@ -161,6 +177,10 @@ bool FffPolygonGenerator::sliceModel(MeshGroup* meshgroup, TimeKeeper& timeKeepe
                 SupportLayer& support_layer = storage.support.supportLayers[layer_nr];
                 SlicerLayer& slicer_layer = slicer->layers[layer_nr];
                 support_layer.support_mesh.add(slicer_layer.polygons);
+                meshStorage.layers[layer_nr].printZ =
+                    slicer_layer.z
+                    + getSettingInMicrons("layer_height_0")
+                    - initial_slice_z;
             }
             continue;
         }
@@ -297,6 +317,7 @@ void FffPolygonGenerator::slices2polygons(SliceDataStorage& storage, TimeKeeper&
 
     // handle helpers
     storage.primeTower.generatePaths(storage);
+    storage.primeTower.subtractFromSupport(storage);
     
     logDebug("Processing ooze shield\n");
     processOozeShield(storage);
@@ -336,12 +357,24 @@ void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage,
     
     
     // walls
-    for (unsigned int layer_number = 0; layer_number < mesh.layers.size(); layer_number++)
+    int processed_layer_count = 0;
+#pragma omp parallel for default(none) shared(mesh_layer_count, mesh, inset_skin_progress_estimate, processed_layer_count) schedule(dynamic)
+    for(unsigned int layer_number = 0; layer_number < mesh.layers.size(); layer_number++)
     {
         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);
+#ifdef _OPENMP
+        if (omp_get_thread_num() == 0)
+#endif
+        { // progress estimation is done only in one thread so that no two threads message progress at the same time
+            int _processed_layer_count;
+#pragma omp atomic read
+                _processed_layer_count = processed_layer_count;
+            double progress = inset_skin_progress_estimate.progress(_processed_layer_count);
+            Progress::messageProgress(Progress::Stage::INSET_SKIN, progress * 100, 100);
+        }
+#pragma omp atomic
+        processed_layer_count++;
     }
 
     ProgressEstimatorLinear* skin_estimator = new ProgressEstimatorLinear(mesh_layer_count);
@@ -372,15 +405,32 @@ 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 < mesh.layers.size(); layer_number++)
+
+    processed_layer_count = 0;
+#pragma omp parallel default(none) shared(mesh_layer_count, mesh, mesh_max_bottom_layer_count, process_infill, inset_skin_progress_estimate, processed_layer_count)
     {
-        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.
+
+#pragma omp for schedule(dynamic)
+        for (unsigned int layer_number = 0; layer_number < mesh.layers.size(); layer_number++)
         {
-            processSkinsAndInfill(mesh, layer_number, process_infill);
+            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);
+            }
+#ifdef _OPENMP
+            if (omp_get_thread_num() == 0)
+#endif
+            { // progress estimation is done only in one thread so that no two threads message progress at the same time
+                int _processed_layer_count;
+#pragma omp atomic read
+                    _processed_layer_count = processed_layer_count;
+                double progress = inset_skin_progress_estimate.progress(_processed_layer_count);
+                Progress::messageProgress(Progress::Stage::INSET_SKIN, progress * 100, 100);
+            }
+#pragma omp atomic
+                processed_layer_count++;
         }
-        double progress = inset_skin_progress_estimate.progress(layer_number);
-        Progress::messageProgress(Progress::Stage::INSET_SKIN, progress * 100, 100);
     }
 }
 
@@ -420,7 +470,7 @@ void FffPolygonGenerator::processInfillMesh(SliceDataStorage& storage, unsigned
                     if (new_outline.size() == 1)
                     { // we don't have to call splitIntoParts, because a single polygon can only be a single part
                         PolygonsPart outline_part_here;
-                        outline_part_here.add(new_outline[0]);
+                        outline_part_here.add(PolygonRef{new_outline[0]});
                         new_parts.push_back(outline_part_here);
                     }
                     else if (new_outline.size() > 1)
@@ -460,8 +510,14 @@ 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
@@ -471,6 +527,14 @@ void FffPolygonGenerator::processDerivedWallsSkinInfill(SliceMeshStorage& mesh)
     }
 }
 
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateInsets only reads and writes data for the current layer
+ *
+ * processInsets only reads and writes data for the current layer
+ */
 void FffPolygonGenerator::processInsets(SliceMeshStorage& mesh, unsigned int layer_nr) 
 {
     SliceLayer* layer = &mesh.layers[layer_nr];
@@ -509,11 +573,19 @@ void FffPolygonGenerator::removeEmptyFirstLayers(SliceDataStorage& storage, cons
         for (SliceMeshStorage& mesh : storage.meshes)
         {
             SliceLayer& layer = mesh.layers[layer_idx];
-            if (layer.parts.size() > 0 || (mesh.getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL && layer.openPolyLines.size() > 0) )
+            if (mesh.getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL && layer.openPolyLines.size() > 0)
             {
                 layer_is_empty = false;
                 break;
             }
+            for (const SliceLayerPart& part : layer.parts)
+            {
+                if (part.print_outline.size() > 0)
+                {
+                    layer_is_empty = false;
+                    break;
+                }
+            }
         }
         
         if (layer_is_empty) 
@@ -544,8 +616,18 @@ void FffPolygonGenerator::removeEmptyFirstLayers(SliceDataStorage& storage, cons
         support_layers.erase(support_layers.begin(), support_layers.begin() + n_empty_first_layers);
     }
 }
-  
-void FffPolygonGenerator::processSkinsAndInfill(SliceMeshStorage& mesh, unsigned int layer_nr, bool process_infill) 
+
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateSkins read (depend on) data from mesh.layers[*].parts[*].insets and write mesh.layers[n].parts[*].skin_parts
+ * generateInfill read mesh.layers[n].parts[*].{insets,skin_parts,boundingBox} and write mesh.layers[n].parts[*].infill_area
+ *
+ * processSkinsAndInfill read (depend on) mesh.layers[*].parts[*].{insets,boundingBox}.
+ *                       write mesh.layers[n].parts[*].{skin_parts,infill_area}.
+ */
+void FffPolygonGenerator::processSkinsAndInfill(SliceMeshStorage& mesh, unsigned int layer_nr, bool process_infill)
 {
     if (mesh.getSettingAsSurfaceMode("magic_mesh_surface_mode") == ESurfaceMode::SURFACE) 
     { 

src/GCodePathConfig.cpp

@@ -67,37 +67,37 @@ void GCodePathConfig::setSpeedIconic()
     current_config.jerk = iconic_config.jerk;
 }
 
-double GCodePathConfig::getExtrusionMM3perMM()
+double GCodePathConfig::getExtrusionMM3perMM() const
 {
     return extrusion_mm3_per_mm;
 }
 
-double GCodePathConfig::getSpeed()
+double GCodePathConfig::getSpeed() const
 {
     return current_config.speed;
 }
 
-double GCodePathConfig::getAcceleration()
+double GCodePathConfig::getAcceleration() const
 {
     return current_config.acceleration;
 }
 
-double GCodePathConfig::getJerk()
+double GCodePathConfig::getJerk() const
 {
     return current_config.jerk;
 }
 
-int GCodePathConfig::getLineWidth()
+int GCodePathConfig::getLineWidth() const
 {
     return current_config.line_width;
 }
 
-bool GCodePathConfig::isTravelPath()
+bool GCodePathConfig::isTravelPath() const
 {
     return current_config.line_width == 0;
 }
 
-double GCodePathConfig::getFlowPercentage()
+double GCodePathConfig::getFlowPercentage() const
 {
     return current_config.flow;
 }

src/GCodePathConfig.h

@@ -79,28 +79,28 @@ public:
     /*!
      * Can only be called after the layer height has been set (which is done while writing the gcode!)
      */
-    double getExtrusionMM3perMM();
+    double getExtrusionMM3perMM() const;
 
     /*!
      * Get the movement speed in mm/s
      */
-    double getSpeed();
+    double getSpeed() const;
 
     /*!
      * Get the current acceleration of this config
      */
-    double getAcceleration();
+    double getAcceleration() const;
 
     /*!
      * Get the current jerk of this config
      */
-    double getJerk();
+    double getJerk() const;
 
-    int getLineWidth();
+    int getLineWidth() const;
 
-    bool isTravelPath();
+    bool isTravelPath() const;
 
-    double getFlowPercentage();
+    double getFlowPercentage() const;
 
 private:
     void calculateExtrusion();

src/LayerPlanBuffer.cpp

@@ -7,6 +7,31 @@
 
 namespace cura {
 
+void issueWriteGCode_impl(
+    GCodeExport* p_gcode,
+    GCodePlanner* p_front_buffer
+){
+#pragma omp task default(none) firstprivate(p_gcode, p_front_buffer)
+    { MULTITHREAD_TASK_CATCH_EXCEPTION(
+        GCodeExport& gcode_ref = *p_gcode;
+#ifdef _OPENMP
+        omp_lock_guard_t<omp_nest_lock_type> gcode_output_lock_guard(gcode_ref.getOutputStreamLock());
+#endif
+        p_front_buffer->writeGCode(gcode_ref);
+        if (CommandSocket::isInstantiated())
+        {
+            CommandSocket::getInstance()->flushGcode();
+        }
+    )}
+}
+
+void LayerPlanBuffer::issueWriteGCode()
+{
+    assert(!(buffer.front().isGCodeWritten()) && "GCode shouldn't be written more than once");
+    GCodeExport* p_gcode = &gcode;
+    GCodePlanner* p_front_buffer = &buffer.front();
+    issueWriteGCode_impl(p_gcode, p_front_buffer);
+}
 
 
 void LayerPlanBuffer::flush()
@@ -15,6 +40,10 @@ void LayerPlanBuffer::flush()
     {
         insertTempCommands(); // insert preheat commands of the very last layer
     }
+
+#ifdef _OPENMP
+    omp_lock_guard_t<omp_nest_lock_type> gcode_output_lock_guard(gcode.getOutputStreamLock());
+#endif
     while (!buffer.empty())
     {
         buffer.front().writeGCode(gcode);
@@ -30,9 +59,10 @@ void LayerPlanBuffer::flush()
 void LayerPlanBuffer::insertPreheatCommand(ExtruderPlan& extruder_plan_before, double time_after_extruder_plan_start, int extruder, double temp)
 {
     double acc_time = 0.0;
-    for (unsigned int path_idx = extruder_plan_before.paths.size() - 1; int(path_idx) != -1 ; path_idx--)
+    std::vector<GCodePath>& extruder_plan_before_paths = extruder_plan_before.getPaths();
+    for (unsigned int path_idx = extruder_plan_before_paths.size() - 1; int(path_idx) != -1 ; path_idx--)
     {
-        GCodePath& path = extruder_plan_before.paths[path_idx];
+        GCodePath& path = extruder_plan_before_paths[path_idx];
         const double time_this_path = path.estimates.getTotalTime();
         acc_time += time_this_path;
         if (acc_time > time_after_extruder_plan_start)
@@ -195,9 +225,9 @@ void LayerPlanBuffer::insertPrintTempCommand(ExtruderPlan& extruder_plan)
     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++)
+        for (path_idx = 0; path_idx < extruder_plan.getPaths().size(); path_idx++)
         {
-            GCodePath& path = extruder_plan.paths[path_idx];
+            GCodePath& path = extruder_plan.getPaths()[path_idx];
             heated_pre_travel_time += path.estimates.getTotalTime();
             if (!path.isTravelPath())
             {
@@ -224,9 +254,9 @@ void LayerPlanBuffer::insertFinalPrintTempCommand(std::vector<ExtruderPlan*>& ex
     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--)
+        for (path_idx = last_extruder_plan.getPaths().size() - 1; int(path_idx) >= 0; path_idx--)
         {
-            GCodePath& path = last_extruder_plan.paths[path_idx];
+            GCodePath& path = last_extruder_plan.getPaths()[path_idx];
             if (!path.isTravelPath())
             {
                 break;
@@ -251,7 +281,7 @@ void LayerPlanBuffer::insertFinalPrintTempCommand(std::vector<ExtruderPlan*>& ex
             time_window += prev_extruder_plan_time;
             heated_pre_travel_time = prev_extruder_plan.heated_pre_travel_time;
 
-            if (prev_extruder_plan.estimates.getTotalUnretractedTime() > 0 && prev_extruder_plan.estimates.getMaterial() > 0)
+            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;
@@ -306,9 +336,9 @@ void LayerPlanBuffer::insertFinalPrintTempCommand(std::vector<ExtruderPlan*>& ex
     { // 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--)
+        for (path_idx = precool_extruder_plan->getPaths().size() - 1; int(path_idx) >= 0; path_idx--)
         {
-            GCodePath& path = precool_extruder_plan->paths[path_idx];
+            GCodePath& path = precool_extruder_plan->getPaths()[path_idx];
             extrusion_time_seen += path.estimates.getTotalTime();
             if (extrusion_time_seen >= cool_down_time)
             {
@@ -324,11 +354,16 @@ void LayerPlanBuffer::insertFinalPrintTempCommand(std::vector<ExtruderPlan*>& ex
 
 void LayerPlanBuffer::insertTempCommands()
 {
-    if (buffer.back().extruder_plans.size() == 0 || (buffer.back().extruder_plans.size() == 1 && buffer.back().extruder_plans[0].paths.size() == 0))
+    if (buffer.back().extruder_plans.size() == 0 || (buffer.back().extruder_plans.size() == 1 && buffer.back().extruder_plans[0].getPathsList().empty()))
     { // disregard empty layer
         buffer.pop_back();
         return;
     }
+    for (ExtruderPlan& plan: buffer.back().extruder_plans)
+    {
+        plan.convertListToVector();
+    }
+
 
     std::vector<ExtruderPlan*> extruder_plans;
     extruder_plans.reserve(buffer.size() * 2);
@@ -349,9 +384,7 @@ void LayerPlanBuffer::insertTempCommands()
         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;
         }

src/LayerPlanBuffer.h

@@ -57,28 +57,40 @@ public:
     
     /*!
      * Place a new layer plan (GcodePlanner) by constructing it with the given arguments.
-     * Pop back the oldest layer plan is it exceeds the buffer size and write it to gcode.
      */
     template<typename... Args>
-    GCodePlanner& emplace_back(Args&&... constructor_args)
+    GCodePlanner& createPlanner(Args&&... constructor_args)
     {
         if (buffer.size() > 0)
         {
             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)
         {
-            buffer.front().writeGCode(gcode);
-            if (CommandSocket::isInstantiated())
-            {
-                CommandSocket::getInstance()->flushGcode();
-            }
-            buffer.pop_front();
+            issueWriteGCode();
         }
         return buffer.back();
     }
     
+    /*
+     * Write GCode for the oldest layer plan.
+     */
+    void issueWriteGCode();
+
+    /*
+     * Pop back the oldest layer plan if it exceeds the buffer size and it has been written to gcode.
+     */
+    void trimBuffer()
+    {
+        if (buffer.size() > buffer_size)
+        {
+            assert(buffer.front().isGCodeWritten() && "GCode should be written before planner is discarded");
+            buffer.pop_front();
+        }
+    }
+    
     /*!
      * Write all remaining layer plans (GCodePlanner) to gcode and empty the buffer.
      */

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);

src/Preheat.cpp

@@ -82,12 +82,6 @@ Preheat::WarmUpResult Preheat::getWarmUpPointAfterCoolDown(double time_window, u
         result.heating_time = extra_heatup_time;
         limited_time_window = time_window - extra_heatup_time;
         outer_temp = temp_start;
-        if (limited_time_window < 0.0)
-        {
-            result.heating_time = 0.0;
-            result.lowest_temperature = temp_start;
-            return result;
-        }
     }
     else
     {
@@ -95,13 +89,14 @@ Preheat::WarmUpResult Preheat::getWarmUpPointAfterCoolDown(double time_window, u
         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 = temp_end;
-            return result;
-        }
     }
+    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);
@@ -150,12 +145,6 @@ Preheat::CoolDownResult Preheat::getCoolDownPointAfterWarmUp(double time_window,
         result.cooling_time = 0;
         limited_time_window = time_window - extra_heatup_time;
         outer_temp = temp_end;
-        if (limited_time_window < 0.0)
-        {
-            result.cooling_time = 0.0;
-            result.highest_temperature = temp_end;
-            return result;
-        }
     }
     else
     {
@@ -163,12 +152,12 @@ Preheat::CoolDownResult Preheat::getCoolDownPointAfterWarmUp(double time_window,
         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 = temp_start;
-            return result;
-        }
+    }
+    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);

src/Preheat.h

@@ -117,7 +117,6 @@ public:
     {
         return config_per_extruder[extruder_nr].flow_dependent_temperature;
     }
-public:
     /*!
      * Get the optimal temperature corresponding to a given average flow,
      * or the initial layer temperature.

src/PrimeTower.cpp

@@ -12,7 +12,7 @@
 namespace cura 
 {
 
-PrimeTower::PrimeTower()
+PrimeTower::PrimeTower(const SliceDataStorage& storage)
 : is_hollow(false)
 , wipe_from_middle(false)
 , current_pre_wipe_location_idx(0)
@@ -21,6 +21,13 @@ PrimeTower::PrimeTower()
     {
         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);
+    }
 }
 
 
@@ -83,10 +90,7 @@ void PrimeTower::generateGroundpoly(const SliceDataStorage& storage)
 
 void PrimeTower::generatePaths(const SliceDataStorage& storage)
 {
-    enabled = storage.max_print_height_second_to_last_extruder >= 0
-            && storage.getSettingBoolean("prime_tower_enable")
-            && storage.getSettingInMicrons("prime_tower_wall_thickness") > 10
-            && storage.getSettingInMicrons("prime_tower_size") > 10;
+    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);
@@ -100,8 +104,6 @@ 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++)
@@ -160,7 +162,7 @@ void PrimeTower::addToGcode(const SliceDataStorage& storage, GCodePlanner& gcode
         preWipe(storage, gcodeLayer, new_extruder);
     }
 
-    addToGcode_denseInfill(storage, gcodeLayer, gcode, layer_nr, prev_extruder, new_extruder);
+    addToGcode_denseInfill(gcodeLayer, layer_nr, new_extruder);
 
     // post-wipe:
     if (post_wipe)
@@ -169,16 +171,15 @@ void PrimeTower::addToGcode(const SliceDataStorage& storage, GCodePlanner& gcode
     }
 }
 
-void PrimeTower::addToGcode_denseInfill(const SliceDataStorage& storage, GCodePlanner& gcodeLayer, const GCodeExport& gcode, const int layer_nr, const int prev_extruder, const int new_extruder)
+void PrimeTower::addToGcode_denseInfill(GCodePlanner& gcodeLayer, const int layer_nr, const int extruder)
 {
-    ExtrusionMoves& pattern = patterns_per_extruder[new_extruder][((layer_nr % 2) + 2) % 2]; // +2) %2 to handle negative layer numbers
+    ExtrusionMoves& pattern = patterns_per_extruder[extruder][((layer_nr % 2) + 2) % 2]; // +2) %2 to handle negative layer numbers
 
-    GCodePathConfig& config = config_per_extruder[new_extruder];
+    GCodePathConfig& config = config_per_extruder[extruder];
 
     gcodeLayer.addPolygonsByOptimizer(pattern.polygons, &config);
     gcodeLayer.addLinesByOptimizer(pattern.lines, &config, SpaceFillType::Lines);
-
-    last_prime_tower_poly_printed[new_extruder] = layer_nr;
+    last_prime_tower_poly_printed[extruder] = layer_nr;
 }
 
 Point PrimeTower::getLocationBeforePrimeTower(const SliceDataStorage& storage)
@@ -295,5 +296,14 @@ void PrimeTower::preWipe(const SliceDataStorage& storage, GCodePlanner& gcode_la
     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
 
@@ -30,8 +33,6 @@ private:
         Polygons polygons;
         Polygons lines;
     };
-    bool enabled; //!< Whether the prime tower is enabled
-
     int extruder_count; //!< number of extruders
     std::vector<GCodePathConfig> config_per_extruder; //!< Path config for prime tower for each extruder
 
@@ -49,10 +50,19 @@ private:
     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.
      * 
@@ -85,8 +95,6 @@ public:
      */
     void generatePaths(const SliceDataStorage& storage);
 
-    PrimeTower(); //!< basic constructor
-
     /*!
      * Add path plans for the prime tower to the \p gcode_layer
      * 
@@ -97,6 +105,15 @@ public:
      * \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, 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.  
@@ -134,16 +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 new_extruder The switched to extruder with which the prime tower paths should be generated.
+     * \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, const int new_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"
 
@@ -19,6 +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 = 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)
         {
@@ -44,13 +48,20 @@ void SkirtBrim::getFirstLayerOutline(SliceDataStorage& storage, const unsigned i
             first_layer_outline.add(support_layer.supportAreas);
             first_layer_outline.add(support_layer.skin);
         }
-        first_layer_outline.add(storage.primeTower.ground_poly); // don't remove parts of the prime tower, but make a brim for it
+        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
     constexpr int smallest_line_length = 200;
     constexpr int largest_error_of_removed_point = 50;
     first_layer_outline.simplify(smallest_line_length, largest_error_of_removed_point); // simplify for faster processing of the brim lines
+    if (first_layer_outline.size() == 0)
+    {
+        logError("Couldn't generate skirt / brim! No polygons on first layer.");
+    }
 }
 
 int SkirtBrim::generatePrimarySkirtBrimLines(SliceDataStorage& storage, int start_distance, unsigned int primary_line_count, const int primary_extruder_skirt_brim_line_width, const int64_t primary_extruder_minimal_length, const Polygons& first_layer_outline, Polygons& skirt_brim_primary_extruder)
@@ -66,7 +77,7 @@ int SkirtBrim::generatePrimarySkirtBrimLines(SliceDataStorage& storage, int star
         //Remove small inner skirt and brim holes. Holes have a negative area, remove anything smaller then 100x extrusion "area"
         for (unsigned int n = 0; n < outer_skirt_brim_line.size(); n++)
         {
-            double area = outer_skirt_brim_line[n].area();
+            double area = PolygonRef{outer_skirt_brim_line[n]}.area();
             if (area < 0 && area > -primary_extruder_skirt_brim_line_width * primary_extruder_skirt_brim_line_width * 100)
             {
                 outer_skirt_brim_line.remove(n--);

src/WallsComputation.cpp

@@ -12,6 +12,12 @@ WallsComputation::WallsComputation(int wall_0_inset, int line_width_0, int line_
 {
 }
 
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateInsets only reads and writes data for the current layer
+ */
 void WallsComputation::generateInsets(SliceLayerPart* part)
 {
     if (insetCount == 0)
@@ -58,6 +64,12 @@ void WallsComputation::generateInsets(SliceLayerPart* part)
     }
 }
 
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateInsets only reads and writes data for the current layer
+ */
 void WallsComputation::generateInsets(SliceLayer* layer)
 {
     for(unsigned int partNr = 0; partNr < layer->parts.size(); partNr++)

src/Weaver.cpp

@@ -209,11 +209,11 @@ void Weaver::fillRoofs(Polygons& supporting, Polygons& to_be_supported, int dire
         std::vector<PolygonsPart> roof_parts = roofs.splitIntoParts();
         for (PolygonsPart& roof_part : roof_parts)
         {
-            roof_outlines.add(roof_part[0]);
+            roof_outlines.add(PolygonRef{roof_part[0]});
             for (unsigned int hole_idx = 1; hole_idx < roof_part.size(); hole_idx++)
             {
-                roof_holes.add(roof_part[hole_idx]);
-                roof_holes.back().reverse();
+                roof_holes.add(PolygonRef{roof_part[hole_idx]});
+                PolygonRef{roof_holes.back()}.reverse();
             }
         }
     }
@@ -223,7 +223,7 @@ void Weaver::fillRoofs(Polygons& supporting, Polygons& to_be_supported, int dire
     
     std::vector<PolygonsPart> supporting_parts = supporting.splitIntoParts();
     for (PolygonsPart& supporting_part : supporting_parts) 
-        supporting_outlines.add(supporting_part[0]); // only add outlines, not the holes
+        supporting_outlines.add(PolygonRef{supporting_part[0]}); // only add outlines, not the holes
     
     
     
@@ -274,10 +274,10 @@ void Weaver::fillFloors(Polygons& supporting, Polygons& to_be_supported, int dir
     Polygons floor_holes;
     for (PolygonsPart& floor_part : floor_parts)
     {
-        floor_outlines.add(floor_part[0]);
+        floor_outlines.add(PolygonRef{floor_part[0]});
         for (unsigned int hole_idx = 1; hole_idx < floor_part.size(); hole_idx++)
         {
-            floor_holes.add(floor_part[hole_idx]);
+            floor_holes.add(PolygonRef{floor_part[hole_idx]});
             //floor_holes.back().reverse();
         }
     }

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/bridge.cpp

@@ -5,7 +5,7 @@
 
 namespace cura {
 
-int bridgeAngle(Polygons outline, SliceLayer* prevLayer)
+int bridgeAngle(Polygons outline, const SliceLayer* prevLayer)
 {
     AABB boundaryBox(outline);
     //To detect if we have a bridge, first calculate the intersection of the current layer with the previous layer.
@@ -29,9 +29,9 @@ int bridgeAngle(Polygons outline, SliceLayer* prevLayer)
     for(unsigned int n=0; n<islands.size(); n++)
     {
         //Skip internal holes
-        if (!islands[n].orientation())
+        if (!PolygonRef{islands[n]}.orientation())
             continue;
-        double area = fabs(islands[n].area());
+        double area = fabs(PolygonRef{islands[n]}.area());
         if (area > area1)
         {
             if (area1 > area2)
@@ -51,8 +51,8 @@ int bridgeAngle(Polygons outline, SliceLayer* prevLayer)
     if (idx1 < 0 || idx2 < 0)
         return -1;
     
-    Point center1 = islands[idx1].centerOfMass();
-    Point center2 = islands[idx2].centerOfMass();
+    Point center1 = PolygonRef{islands[idx1]}.centerOfMass();
+    Point center2 = PolygonRef{islands[idx2]}.centerOfMass();
 
     return angle(center2 - center1);
 }

src/bridge.h

@@ -6,7 +6,7 @@ namespace cura {
     class Polygons;
     class SliceLayer;
 
-int bridgeAngle(Polygons outline, SliceLayer* prevLayer);
+int bridgeAngle(Polygons outline, const SliceLayer* prevLayer);
 
 }//namespace cura
 

src/commandSocket.cpp

@@ -215,7 +215,7 @@ public:
     /*!
      * Adds closed polygon to the current path
      */
-    void sendPolygon(PrintFeatureType print_feature_type, Polygon poly, int width);
+    void sendPolygon(PrintFeatureType print_feature_type, ConstPolygonRef poly, int width);
 private:
     /*!
      * Convert and add a point to the points buffer, each point being represented as two consecutive floats. All members adding a 2D point to the data should use this function.
@@ -522,7 +522,7 @@ void CommandSocket::sendPolygons(PrintFeatureType type, const Polygons& polygons
 #endif
 }
 
-void CommandSocket::sendPolygon(PrintFeatureType type, Polygon& polygon, int line_width)
+void CommandSocket::sendPolygon(PrintFeatureType type, ConstPolygonRef polygon, int line_width)
 {
 #ifdef ARCUS
     if (CommandSocket::isInstantiated())
@@ -797,7 +797,7 @@ void CommandSocket::PathCompiler::sendLineTo(PrintFeatureType print_feature_type
     }
 }
 
-void CommandSocket::PathCompiler::sendPolygon(PrintFeatureType print_feature_type, Polygon polygon, int width)
+void CommandSocket::PathCompiler::sendPolygon(PrintFeatureType print_feature_type, ConstPolygonRef polygon, int width)
 {
     if (polygon.size() < 2)
     {

src/commandSocket.h

@@ -64,7 +64,7 @@ public:
     /*! 
      * Send a polygon to the front-end. This is used for the layerview in the GUI
      */
-    static void sendPolygon(cura::PrintFeatureType type, Polygon& polygon, int line_width);
+    static void sendPolygon(cura::PrintFeatureType type, ConstPolygonRef polygon, int line_width);
 
     /*!
      * Send a line to the front-end. This is used for the layerview in the GUI

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))
@@ -97,6 +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";
@@ -109,20 +113,15 @@ 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)
 {
-    int start_extruder_nr = 0;
-    if (settings.getSettingAsPlatformAdhesion("adhesion_type") != EPlatformAdhesion::NONE)
-    {
-        start_extruder_nr = settings.getSettingAsIndex("adhesion_extruder_nr");
-    }
     for (unsigned int extr_nr = 0; extr_nr < extruder_count; extr_nr++)
     {
         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 = ((int)extr_nr == start_extruder_nr)? print_temp_here : train.getSettingInDegreeCelsius("material_standby_temperature");
+        double temp = (extr_nr == start_extruder_nr)? print_temp_here : train.getSettingInDegreeCelsius("material_standby_temperature");
         setInitialTemp(extr_nr, temp);
     }
 
@@ -196,6 +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();
     }
 }
@@ -552,8 +556,6 @@ void GCodeExport::writeMove(int x, int y, int z, double speed, double extrusion_
     assert((Point3(x,y,z) - currentPosition).vSize() < MM2INT(300)); // no crazy positions (this code should not be compiled for release)
 #endif //ASSERT_INSANE_OUTPUT
 
-    total_bounding_box.include(Point3(x, y, z));
-
     if (extrusion_mm3_per_mm < 0)
         logWarning("Warning! Negative extrusion move!");
 
@@ -566,6 +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)
     {
@@ -639,7 +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];
 
@@ -656,7 +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)
     {
@@ -666,23 +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();
         }
@@ -705,17 +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;
 
 }
 
@@ -725,7 +728,7 @@ void GCodeExport::writeZhopStart(int hop_height)
     {
         isZHopped = hop_height;
         *output_stream << "G1 Z" << MMtoStream{currentPosition.z + isZHopped} << new_line;
-        total_bounding_box.include(currentPosition + Point3(0, 0, isZHopped));
+        total_bounding_box.includeZ(currentPosition.z + isZHopped);
     }
 }
 
@@ -772,7 +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(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
 
@@ -904,7 +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

@@ -13,6 +13,7 @@
 #include "MeshGroup.h"
 #include "commandSocket.h"
 #include "RetractionConfig.h"
+#include "multithreadOpenMP.h"
 
 namespace cura {
 
@@ -90,6 +91,9 @@ private:
     std::string machine_name;
 
     std::ostream* output_stream;
+#ifdef _OPENMP
+    omp_nest_lock_type output_stream_lock;
+#endif
     std::string new_line;
 
     double current_e_value; //!< The last E value written to gcode (in mm or mm^3)
@@ -177,6 +181,13 @@ public:
     
     void setOutputStream(std::ostream* stream);
 
+#ifdef _OPENMP
+    omp_nest_lock_type& getOutputStreamLock()
+    {
+        return output_stream_lock;
+    }
+#endif
+
     bool getExtruderIsUsed(const int extruder_nr) const; //!< Returns whether the extruder with the given index is used up until the current meshgroup
 
     int getNozzleSize(const int extruder_nr) const;
@@ -261,7 +272,7 @@ 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
@@ -349,13 +360,17 @@ 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

@@ -9,22 +9,10 @@
 
 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, bool is_initial_layer, int layer_thickness, FanSpeedLayerTimeSettings& fan_speed_layer_time_settings, const RetractionConfig& retraction_config)
-: extruder(extruder)
+: is_paths_vector_initialised(false)
+, extruder(extruder)
 , heated_pre_travel_time(0)
 , initial_printing_temperature(-1)
 , printing_temperature(-1)
@@ -67,16 +55,30 @@ double ExtruderPlan::getFanSpeed()
 {
     return fan_speed;
 }
-
-
-GCodePath* GCodePlanner::getLatestPathWithConfig(GCodePathConfig* config, SpaceFillType space_fill_type, float flow, bool spiralize)
+void ExtruderPlan::convertListToVector()
 {
-    std::vector<GCodePath>& paths = extruder_plans.back().paths;
+    unsigned int number_of_paths = paths_list.size();
+    paths_vector.reserve(number_of_paths);
+    for (auto path : paths_list)
+    {
+        if (path.points.size())
+        {
+            paths_vector.emplace_back(std::move(path));
+        }
+    }
+    is_paths_vector_initialised = true;
+}
+
+
+GCodePath* GCodePlanner::getLatestPathWithConfig(const GCodePathConfig* config, SpaceFillType space_fill_type, float flow, bool spiralize)
+{
+    std::list<GCodePath>& paths = extruder_plans.back().getPathsList();
     if (paths.size() > 0 && paths.back().config == config && !paths.back().done && paths.back().flow == flow) // spiralize can only change when a travel path is in between
         return &paths.back();
     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;
@@ -88,12 +90,12 @@ GCodePath* GCodePlanner::getLatestPathWithConfig(GCodePathConfig* config, SpaceF
 
 void GCodePlanner::forceNewPathStart()
 {
-    std::vector<GCodePath>& paths = extruder_plans.back().paths;
+    std::list<GCodePath>& paths = extruder_plans.back().getPathsList();
     if (paths.size() > 0)
-        paths[paths.size()-1].done = true;
+        paths.back().done = true;
 }
 
-GCodePlanner::GCodePlanner(SliceDataStorage& storage, int layer_nr, int z, int layer_thickness, Point last_position, int current_extruder, 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))
@@ -105,12 +107,13 @@ GCodePlanner::GCodePlanner(SliceDataStorage& storage, int layer_nr, int z, int l
 , last_planned_extruder_setting_base(storage.meshgroup->getExtruderTrain(current_extruder))
 , comb_boundary_inside(computeCombBoundaryInside(combing_mode))
 , fan_speed_layer_time_settings_per_extruder(fan_speed_layer_time_settings_per_extruder)
+, gcode_written(0)
 {
     extruder_plans.reserve(storage.meshgroup->getExtruderCount());
     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 = storage.getPartInside(layer_nr, start_position);
-    is_inside = nullptr; // assumes the next move will not be to inside a layer part (overwritten just before going into a layer part)
+    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)
     if (combing_mode != CombingMode::OFF)
     {
         comb = new Comb(storage, layer_nr, comb_boundary_inside, comb_boundary_offset, travel_avoid_other_parts, travel_avoid_distance);
@@ -139,7 +142,14 @@ Polygons GCodePlanner::computeCombBoundaryInside(CombingMode combing_mode)
     }
     if (layer_nr < 0)
     { // when a raft is present
-        return Polygons();
+        if (combing_mode == CombingMode::NO_SKIN)
+        {
+            return Polygons();
+        }
+        else
+        {
+            return storage.raftOutline.offset(MM2INT(0.1));
+        }
     }
     else 
     {
@@ -167,7 +177,7 @@ Polygons GCodePlanner::computeCombBoundaryInside(CombingMode combing_mode)
     }
 }
 
-void GCodePlanner::setIsInside(SliceLayerPart* _is_inside)
+void GCodePlanner::setIsInside(bool _is_inside)
 {
     is_inside = _is_inside;
 }
@@ -178,7 +188,7 @@ bool GCodePlanner::setExtruder(int extruder)
     {
         return false;
     }
-    setIsInside(nullptr);
+    setIsInside(false);
     { // handle end position of the prev extruder
         SettingsBaseVirtual* train = getLastPlannedExtruderTrainSettings();
         bool end_pos_absolute = train->getSettingBoolean("machine_extruder_end_pos_abs");
@@ -194,7 +204,7 @@ bool GCodePlanner::setExtruder(int extruder)
         }
         addTravel(end_pos); //  + extruder_offset cause it 
     }
-    if (extruder_plans.back().paths.empty() && extruder_plans.back().inserts.empty())
+    if (extruder_plans.back().getPathsList().empty() && extruder_plans.back().inserts.empty())
     { // first extruder plan in a layer might be empty, cause it is made with the last extruder planned in the previous layer
         extruder_plans.back().extruder = extruder;
     }
@@ -225,27 +235,11 @@ bool GCodePlanner::setExtruder(int extruder)
     return true;
 }
 
-void GCodePlanner::moveInsideCombBoundary(int distance, const SliceLayerPart& part)
+void GCodePlanner::moveInsideCombBoundary(int distance)
 {
-    // this function is to be used to move from the boudary of a part to inside the part
     int max_dist2 = MM2INT(2.0) * MM2INT(2.0); // if we are further than this distance, we conclude we are not inside even though we thought we were.
+    // this function is to be used to move from the boudary of a part to inside the part
     Point p = lastPosition; // copy, since we are going to move p
-    { // first move inside the last part, so that the chance is higher that we move inside the same part
-        const Polygons* comb_boundary_here;
-        if (part.insets.size() > 1)
-        {
-            comb_boundary_here = &part.insets[1];
-        }
-        else if (part.insets.size() == 1)
-        {
-            comb_boundary_here = &part.insets[0];
-        }
-        else
-        {
-            comb_boundary_here = &part.print_outline;
-        }
-        PolygonUtils::moveInside(*comb_boundary_here, p, distance);
-    }
     if (PolygonUtils::moveInside(comb_boundary_inside, p, distance, max_dist2) != NO_INDEX)
     {
         //Move inside again, so we move out of tight 90deg corners
@@ -271,7 +265,7 @@ GCodePath& GCodePlanner::addTravel(Point p)
 
     const bool perform_z_hops = extr->getSettingBoolean("retraction_hop_enabled");
 
-    const bool is_first_travel_of_extruder_after_switch = extruder_plans.back().paths.size() == 0 && (extruder_plans.size() > 1 || last_extruder_previous_layer != getExtruder());
+    const bool is_first_travel_of_extruder_after_switch = extruder_plans.back().getPathsList().size() == 0 && (extruder_plans.size() > 1 || last_extruder_previous_layer != getExtruder());
     const bool bypass_combing = is_first_travel_of_extruder_after_switch && extr->getSettingBoolean("retraction_hop_after_extruder_switch");
 
     if (comb != nullptr && !bypass_combing && lastPosition != no_point)
@@ -337,7 +331,7 @@ GCodePath& GCodePlanner::addTravel(Point p)
             if (was_inside) // when the previous location was from printing something which is considered inside (not support or prime tower etc)
             {               // then move inside the printed part, so that we don't ooze on the outer wall while retraction, but on the inside of the print.
                 assert (extr != nullptr);
-                moveInsideCombBoundary(extr->getSettingInMicrons((extr->getSettingAsCount("wall_line_count") > 1) ? "wall_line_width_x" : "wall_line_width_0") * 1, *was_inside);
+                moveInsideCombBoundary(extr->getSettingInMicrons((extr->getSettingAsCount("wall_line_count") > 1) ? "wall_line_width_x" : "wall_line_width_0") * 1);
             }
             path = getLatestPathWithConfig(&travel_config, SpaceFillType::None);
             path->retract = true;
@@ -361,14 +355,22 @@ GCodePath& GCodePlanner::addTravel_simple(Point p, GCodePath* path)
     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)
+void GCodePlanner::addExtrusionMove(Point p, const GCodePathConfig* config, SpaceFillType space_fill_type, float flow, bool spiralize)
 {
     getLatestPathWithConfig(config, space_fill_type, flow, spiralize)->points.push_back(p);
     lastPosition = p;
 }
 
-void GCodePlanner::addPolygon(PolygonRef polygon, int start_idx, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, coord_t wall_0_wipe_dist, bool spiralize)
+void GCodePlanner::addPolygon(ConstPolygonRef polygon, int start_idx, const GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, coord_t wall_0_wipe_dist, bool spiralize)
 {
     Point p0 = polygon[start_idx];
     addTravel(p0);
@@ -381,7 +383,7 @@ void GCodePlanner::addPolygon(PolygonRef polygon, int start_idx, GCodePathConfig
     }
     if (polygon.size() > 2)
     {
-        Point& p1 = polygon[start_idx];
+        const 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);
 
@@ -416,13 +418,13 @@ void GCodePlanner::addPolygon(PolygonRef polygon, int start_idx, GCodePathConfig
     }
 }
 
-void GCodePlanner::addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* config, WallOverlapComputation* wall_overlap_computation, EZSeamType z_seam_type, coord_t wall_0_wipe_dist, bool spiralize)
+void GCodePlanner::addPolygonsByOptimizer(const Polygons& polygons, const 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]);
@@ -433,7 +435,7 @@ void GCodePlanner::addPolygonsByOptimizer(Polygons& polygons, GCodePathConfig* c
         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)
+void GCodePlanner::addLinesByOptimizer(const Polygons& polygons, const GCodePathConfig* config, SpaceFillType space_fill_type, int wipe_dist)
 {
     LineOrderOptimizer orderOptimizer(lastPosition);
     for (unsigned int line_idx = 0; line_idx < polygons.size(); line_idx++)
@@ -443,12 +445,12 @@ void GCodePlanner::addLinesByOptimizer(Polygons& polygons, GCodePathConfig* conf
     orderOptimizer.optimize();
     for (int poly_idx : orderOptimizer.polyOrder)
     {
-        PolygonRef polygon = polygons[poly_idx];
+        ConstPolygonRef polygon = polygons[poly_idx];
         int start = orderOptimizer.polyStart[poly_idx];
         int end = 1 - start;
-        Point& p0 = polygon[start];
+        const Point& p0 = polygon[start];
         addTravel(p0);
-        Point& p1 = polygon[end];
+        const Point& p1 = polygon[end];
         addExtrusionMove(p1, config, space_fill_type);
         if (wipe_dist != 0)
         {
@@ -471,7 +473,7 @@ void ExtruderPlan::forceMinimalLayerTime(double minTime, double minimalSpeed, do
         if (minExtrudeTime < 1)
             minExtrudeTime = 1;
         double factor = extrudeTime / minExtrudeTime;
-        for (GCodePath& path : paths)
+        for (GCodePath& path : getPathsList())
         {
             if (path.isTravelPath())
                 continue;
@@ -495,7 +497,7 @@ void ExtruderPlan::forceMinimalLayerTime(double minTime, double minimalSpeed, do
         
         // Adjust stored naive time estimates
         estimates.extrude_time *= inv_factor;
-        for (GCodePath& path : paths)
+        for (GCodePath& path : getPathsList())
         {
             path.estimates.extrude_time *= inv_factor;
         }
@@ -513,7 +515,7 @@ TimeMaterialEstimates ExtruderPlan::computeNaiveTimeEstimates()
     Point p0 = start_position;
 
     bool was_retracted = false; // wrong assumption; won't matter that much. (TODO)
-    for (GCodePath& path : paths)
+    for (GCodePath& path : getPathsList())
     {
         bool is_extrusion_path = false;
         double* path_time_estimate;
@@ -666,7 +668,7 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
     gcode.setZ(z);
     
     
-    GCodePathConfig* last_extrusion_config = nullptr; // used to check whether we need to insert a TYPE comment in the gcode.
+    const GCodePathConfig* last_extrusion_config = nullptr; // used to check whether we need to insert a TYPE comment in the gcode.
 
     int extruder = gcode.getExtruderNr();
     bool acceleration_enabled = storage.getSettingBoolean("acceleration_enabled");
@@ -696,7 +698,7 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
 
             // 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
@@ -712,10 +714,10 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
         }
         else if (extruder_plan_idx == 0 && layer_nr != 0 && storage.meshgroup->getExtruderTrain(extruder)->getSettingBoolean("retract_at_layer_change"))
         {
-            gcode.writeRetraction(&retraction_config);
+            gcode.writeRetraction(retraction_config);
         }
         gcode.writeFanCommand(extruder_plan.getFanSpeed());
-        std::vector<GCodePath>& paths = extruder_plan.paths;
+        std::vector<GCodePath>& paths = extruder_plan.getPaths();
 
         extruder_plan.inserts.sort([](const NozzleTempInsert& a, const NozzleTempInsert& b) -> bool { 
                 return  a.path_idx < b.path_idx; 
@@ -736,6 +738,12 @@ 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());
@@ -747,7 +755,7 @@ 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);
@@ -866,7 +874,7 @@ 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
@@ -882,6 +890,9 @@ void GCodePlanner::writeGCode(GCodeExport& gcode)
     } // extruder plans /\  .
     
     gcode.updateTotalPrintTime();
+#pragma omp flush
+#pragma omp atomic update
+    ++gcode_written;
 }
 
 void GCodePlanner::overrideFanSpeeds(double speed)
@@ -904,6 +915,7 @@ void GCodePlanner::completeConfigs()
 
         mesh.insetX_config.setLayerHeight(layer_thickness);
         mesh.skin_config.setLayerHeight(layer_thickness);
+        mesh.perimeter_gap_config.setLayerHeight(layer_thickness);
         for(unsigned int idx=0; idx<MAX_INFILL_COMBINE; idx++)
         {
             mesh.infill_config[idx].setLayerHeight(layer_thickness);
@@ -962,6 +974,7 @@ void GCodePlanner::processInitialLayersSpeedup()
 
             //Skin speed (per mesh).
             mesh.skin_config.smoothSpeed(initial_layer_speed_config, layer_nr, initial_speedup_layers);
+            mesh.perimeter_gap_config.smoothSpeed(initial_layer_speed_config, layer_nr, initial_speedup_layers);
 
             for (unsigned int idx = 0; idx < MAX_INFILL_COMBINE; idx++)
             {
@@ -983,6 +996,7 @@ void GCodePlanner::processInitialLayersSpeedup()
             mesh.inset0_config.setSpeedIconic();
             mesh.insetX_config.setSpeedIconic();
             mesh.skin_config.setSpeedIconic();
+            mesh.perimeter_gap_config.setSpeedIconic();
             for (unsigned int idx = 0; idx < MAX_INFILL_COMBINE; idx++)
             {
                 mesh.infill_config[idx].setSpeedIconic();
@@ -995,7 +1009,7 @@ void GCodePlanner::processInitialLayersSpeedup()
 
 bool GCodePlanner::makeRetractSwitchRetract(GCodeExport& gcode, unsigned int extruder_plan_idx, unsigned int path_idx)
 {
-    std::vector<GCodePath>& paths = extruder_plans[extruder_plan_idx].paths;
+    std::vector<GCodePath>& paths = extruder_plans[extruder_plan_idx].getPaths();
     for (unsigned int path_idx2 = path_idx + 1; path_idx2 < paths.size(); path_idx2++)
     {
         if (paths[path_idx2].getExtrusionMM3perMM() > 0) 
@@ -1026,7 +1040,7 @@ bool GCodePlanner::writePathWithCoasting(GCodeExport& gcode, unsigned int extrud
         return false; 
     }
     ExtruderPlan& extruder_plan = extruder_plans[extruder_plan_idx];
-    std::vector<GCodePath>& paths = extruder_plan.paths;
+    std::vector<GCodePath>& paths = extruder_plan.getPaths();
     GCodePath& path = paths[path_idx];
     if (path_idx + 1 >= paths.size()
         ||

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"
@@ -20,252 +23,6 @@ namespace cura
 {
 
 class SliceDataStorage;
-class SliceLayerPart;
-
-/*!
- * 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)
-    {
-        assert(temperature != 0 && temperature != -1 && "Temperature command must be set!");
-    }
-    
-    /*!
-     * 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
@@ -280,9 +37,12 @@ class ExtruderPlan
     friend class GCodePlanner; // TODO: GCodePlanner still does a lot which should actually be handled in this class.
     friend class LayerPlanBuffer; // TODO: LayerPlanBuffer handles paths directly
 protected:
-    std::vector<GCodePath> paths; //!< The paths planned for this extruder
+    std::list<GCodePath> paths_list; //!< The paths planned for this extruder
+    std::vector<GCodePath> paths_vector; //!< The paths planned for this extruder
     std::list<NozzleTempInsert> inserts; //!< The nozzle temperature command inserts, to be inserted in between paths
 
+    bool is_paths_vector_initialised; //!< Keeps information if content of \p paths_list has been copied to \p paths_vector
+
     int extruder; //!< The extruder used for this paths in the current 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.
@@ -344,7 +104,7 @@ public:
         while ( ! inserts.empty() )
         { // handle the Insert to be inserted before this path_idx (and all inserts not handled yet)
             NozzleTempInsert& insert = inserts.front();
-            assert(insert.path_idx == paths.size());
+            assert(insert.path_idx == getPaths().size());
             insert.write(gcode);
             inserts.pop_front();
         }
@@ -399,6 +159,39 @@ public:
      * \return The fan speed computed in processFanSpeedAndMinimalLayerTime
      */
     double getFanSpeed();
+
+    /*!
+     * Move the paths data from the input list to the vector container
+     *
+     * \warning empties the \p paths_list which will no longer contain data. No references to the paths in \p paths_list should be kept.
+     */
+    void convertListToVector();
+
+    /*!
+     * Get the paths in a list container
+     *
+     * \warning should not be called after paths_list has been converted to paths variable
+     *
+     * \return The paths as a list
+     */
+    std::list<GCodePath>& getPathsList()
+    {
+        assert(!is_paths_vector_initialised);
+        return paths_list;
+    }
+
+    /*!
+     * Get the paths in a vector container
+     *
+     * \warning should not be called before paths_list has been converted to paths variable
+     *
+     * \return The paths as a vector
+     */
+    std::vector<GCodePath>& getPaths()
+    {
+        assert(is_paths_vector_initialised);
+        return paths_vector;
+    }
 protected:
 
     Point start_position; //!< The position the print head was at at the start of this extruder plan
@@ -475,14 +268,16 @@ private:
 
     int last_extruder_previous_layer; //!< The last id of the extruder with which was printed in the previous layer
     SettingsBaseVirtual* last_planned_extruder_setting_base; //!< The setting base of the last planned extruder.
-    SliceLayerPart* was_inside; //!< The layer part the last planned (extrusion) move was inside (if any)
-    SliceLayerPart* is_inside; //!< The layer part the destination of the next planned travel move is inside (if any)
+    bool was_inside; //!< Whether the last planned (extrusion) move was inside a layer part
+    bool is_inside; //!< Whether the destination of the next planned travel move is inside a layer part
     Polygons comb_boundary_inside; //!< The boundary within which to comb, or to move into when performing a retraction.
     Comb* comb;
 
 
     std::vector<FanSpeedLayerTimeSettings>& fan_speed_layer_time_settings_per_extruder;
     
+    int gcode_written;
+
 private:
     /*!
      * Either create a new path with the given config or return the last path if it already had that config.
@@ -494,7 +289,7 @@ private:
      * \param spiralize Whether to gradually increase the z while printing. (Note that this path may be part of a sequence of spiralized paths, forming one polygon)
      * \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);
+    GCodePath* getLatestPathWithConfig(const GCodePathConfig* config, SpaceFillType space_fill_type, float flow = 1.0, bool spiralize = false);
 
 public:
     /*!
@@ -517,7 +312,7 @@ 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, int layer_nr, int z, int layer_height, Point last_position, int current_extruder, 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);
@@ -565,10 +360,15 @@ public:
     * 
     * Features like infill, walls, skin etc. are considered inside.
     * Features like prime tower and support are considered outside.
-    * \param inside_part The part in which the newly planned position is inside, or nullptr if not inside anything
     */
-    void setIsInside(SliceLayerPart* inside_part);
-    
+    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);
 
     /*!
@@ -599,6 +399,13 @@ public:
      */
     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.
      * 
@@ -608,7 +415,7 @@ public:
      * \param flow A modifier of the extrusion width which would follow from the \p config
      * \param spiralize Whether to gradually increase the z while printing. (Note that this path may be part of a sequence of spiralized paths, forming one polygon)
      */
-    void addExtrusionMove(Point p, GCodePathConfig* config, SpaceFillType space_fill_type, float flow = 1.0, bool spiralize = false);
+    void addExtrusionMove(Point p, const GCodePathConfig* config, SpaceFillType space_fill_type, float flow = 1.0, bool spiralize = false);
 
     /*!
      * Add polygon to the gcode starting at vertex \p startIdx
@@ -619,7 +426,7 @@ public:
      * \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, coord_t wall_0_wipe_dist = 0, bool spiralize = false);
+    void addPolygon(ConstPolygonRef polygon, int startIdx, const 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.
@@ -634,10 +441,11 @@ 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, coord_t wall_0_wipe_dist = 0, bool spiralize = false);
+    void addPolygonsByOptimizer(const Polygons& polygons, const 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.
@@ -646,7 +454,7 @@ public:
      * \param space_fill_type The type of space filling used to generate the line segments (should be either Lines or PolyLines!)
      * \param wipe_dist (optional) the distance wiped without extruding after laying down a line.
      */
-    void addLinesByOptimizer(Polygons& polygons, GCodePathConfig* config, SpaceFillType space_fill_type, int wipe_dist = 0);
+    void addLinesByOptimizer(const Polygons& polygons, const GCodePathConfig* config, SpaceFillType space_fill_type, int wipe_dist = 0);
 
     /*!
      * Compute naive time estimates (without accounting for slow down at corners etc.) and naive material estimates (without accounting for MergeInfillLines)
@@ -664,7 +472,16 @@ public:
      * \param gcode The gcode to write the planned paths to
      */
     void writeGCode(GCodeExport& gcode);
-    
+    /*!
+     * Has the planned paths been written to gcode
+     */
+    int isGCodeWritten()
+    {
+        int gcode_written_tmp;
+#pragma omp atomic read
+        gcode_written_tmp = gcode_written;
+        return gcode_written_tmp;
+    }
     /*!
      * Complete all GcodePathConfigs by
      * - altering speeds to conform to speed_print_layer_0 and
@@ -715,9 +532,8 @@ public:
      * This is supposed to be called when the nozzle is around the boundary of a layer part, not when the nozzle is in the middle of support, or in the middle of the air.
      * 
      * \param distance The distance to the comb boundary after we moved inside it.
-     * \param part_outline The part in which we last resided
      */
-    void moveInsideCombBoundary(int distance, const SliceLayerPart& part);
+    void moveInsideCombBoundary(int distance);
 };
 
 }//namespace cura

src/infill.cpp

@@ -17,7 +17,7 @@ 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, const SliceMeshStorage* mesh)
 {
     if (in_outline.size() == 0) return;
     if (line_distance == 0) return;
@@ -48,6 +48,14 @@ void Infill::generate(Polygons& result_polygons, Polygons& result_lines)
     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;
@@ -58,7 +66,6 @@ void Infill::generateConcentricInfill(Polygons& result, int inset_value)
 {
     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
 
-    result.add(first_concentric_wall);
     if (perimeter_gaps)
     {
         const Polygons inner = first_concentric_wall.offset(infill_line_width / 2 + perimeter_gaps_extra_offset);
@@ -70,6 +77,7 @@ void Infill::generateConcentricInfill(Polygons& result, int 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)
@@ -79,7 +87,7 @@ void Infill::generateConcentricInfill(Polygons& first_concentric_wall, Polygons&
         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 + 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);
         }
@@ -136,15 +144,26 @@ void Infill::generateTriangleInfill(Polygons& result)
     generateLineInfill(result, line_distance, fill_angle + 120, 0);
 }
 
+void Infill::generateCubicSubDivInfill(Polygons& result, const 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);
@@ -170,7 +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;
     }

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"
 
@@ -77,8 +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, const SliceMeshStorage* mesh = nullptr);
 
 private:
     /*!
@@ -140,7 +142,14 @@ 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, const SliceMeshStorage& mesh);
+
     /*!
      * Convert a mapping from scanline to line_segment-scanline-intersections (\p cut_list) into line segments, using the even-odd rule
      * \param result (output) The resulting lines
@@ -153,6 +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;
+    coord_t 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 coord_t layer_height = mesh.getSettingInMicrons("layer_height");
+    int bottom_layer = (center.z - radius) / layer_height;
+    int top_layer = (center.z + radius) / layer_height;
+    for (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, int layer_nr, Point& location, int64_t* distance2)
+{
+    if (layer_nr < 0 || (unsigned 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, 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

@@ -3,6 +3,7 @@
 #include "layerPart.h"
 #include "settings/settings.h"
 #include "progress/Progress.h"
+#include "multithreadOpenMP.h"
 
 #include "utils/SVG.h" // debug output
 
@@ -28,8 +29,8 @@ void createLayerWithParts(SliceLayer& storageLayer, SlicerLayer* layer, bool uni
     {
         for(unsigned int i=0; i<layer->polygons.size(); i++)
         {
-            if (layer->polygons[i].orientation())
-                layer->polygons[i].reverse();
+            if (PolygonRef{layer->polygons[i]}.orientation())
+                PolygonRef{layer->polygons[i]}.reverse();
         }
     }
     
@@ -44,12 +45,17 @@ void createLayerWithParts(SliceLayer& storageLayer, SlicerLayer* layer, bool uni
 }
 void createLayerParts(SliceMeshStorage& mesh, Slicer* slicer, bool union_layers, bool union_all_remove_holes)
 {
-    for(unsigned int layer_nr = 0; layer_nr < slicer->layers.size(); layer_nr++)
-    {
+    const auto total_layers = slicer->layers.size();
+    // mesh.layers.resize(total_layers); TODO: put this back?
+    assert(mesh.layers.size() == total_layers);
+#pragma omp parallel for default(none) shared(mesh,slicer) firstprivate(union_layers,union_all_remove_holes) schedule(dynamic)
+    for(unsigned int layer_nr = 0; layer_nr < total_layers; layer_nr++)
+    { MULTITHREAD_FOR_CATCH_EXCEPTION(
         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);
-    }
+    )}
+    handleMultithreadAbort();
 }
 
 void layerparts2HTML(SliceDataStorage& storage, const char* filename, bool all_layers, int layer_nr)

src/multithreadOpenMP.cpp

@@ -0,0 +1,21 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+
+#include "multithreadOpenMP.h"
+#include <cstdlib>
+
+namespace cura
+{
+
+bool abort_execution = false;
+
+#ifdef _OPENMP
+void handleMultithreadAbort()
+{
+    if (checkMultithreadAbort())
+    {
+        std::exit(17);
+    }
+}
+#endif
+
+}//namespace cura

src/multithreadOpenMP.h

@@ -0,0 +1,182 @@
+/** Copyright (C) 2016 Ultimaker - Released under terms of the AGPLv3 License */
+
+#ifndef MULTITHREAD_OPENMP_H
+#define MULTITHREAD_OPENMP_H
+
+#include <omp.h>
+
+namespace cura
+{
+
+// TODO: remove
+extern bool abort_execution;
+
+#ifdef _OPENMP
+
+class omp_lock_type
+{
+public:
+    omp_lock_type()
+    {
+        omp_init_lock(&lock_object);
+    }
+    ~omp_lock_type()
+    {
+        omp_destroy_lock(&lock_object);
+    }
+    void lock()
+    {
+        omp_set_lock(&lock_object);
+    }
+    void unlock()
+    {
+        omp_unset_lock(&lock_object);
+    }
+    int test_lock()
+    {
+        return omp_test_lock(&lock_object);
+    }
+private:
+    omp_lock_t lock_object;
+    omp_lock_type( const omp_lock_type& ) = delete;
+    omp_lock_type& operator=( const omp_lock_type& ) = delete;
+};
+
+class omp_nest_lock_type
+{
+public:
+    omp_nest_lock_type()
+    {
+        omp_init_nest_lock(&lock_object);
+    }
+    ~omp_nest_lock_type()
+    {
+        omp_destroy_nest_lock(&lock_object);
+    }
+    void lock()
+    {
+        omp_set_nest_lock(&lock_object);
+    }
+    void unlock()
+    {
+        omp_unset_nest_lock(&lock_object);
+    }
+    int test_lock()
+    {
+        return omp_test_nest_lock(&lock_object);
+    }
+private:
+    omp_nest_lock_t lock_object;
+    omp_nest_lock_type( const omp_nest_lock_type& ) = delete;
+    omp_nest_lock_type& operator=( const omp_nest_lock_type& ) = delete;
+};
+
+template <typename LockType>
+class omp_try_lock_guard_t
+{
+public:
+    omp_try_lock_guard_t( LockType& lock_)
+    : lock(lock_)
+    {
+        has_lock = lock.test_lock();
+    }
+    ~omp_try_lock_guard_t()
+    {
+        if (has_lock)
+        {
+            lock.unlock();
+        }
+    }
+    int isLocked()
+    {
+        return has_lock;
+    }
+private:
+    LockType& lock;
+    int has_lock;
+    omp_try_lock_guard_t( const omp_try_lock_guard_t& ) = delete;
+    omp_try_lock_guard_t<LockType>& operator=( const omp_try_lock_guard_t& ) = delete;
+};
+
+template <typename LockType>
+class omp_lock_guard_t
+{
+public:
+    omp_lock_guard_t( LockType& lock_)
+    : lock(lock_)
+    {
+        lock.lock();
+    }
+    ~omp_lock_guard_t()
+    {
+        lock.unlock();
+    }
+private:
+    LockType& lock;
+    omp_lock_guard_t( const omp_lock_guard_t& ) = delete;
+    omp_lock_guard_t& operator=( const omp_lock_guard_t& ) = delete;
+};
+#endif
+
+// TODO: remove
+inline bool checkMultithreadAbort()
+{
+    bool tmp_abort_execution;
+#pragma omp atomic read
+    tmp_abort_execution = abort_execution;
+    return tmp_abort_execution;
+}
+
+// TODO: remove
+inline void setMultithreadAbort()
+{
+#pragma omp atomic write
+    abort_execution = true;
+}
+
+// TODO: remove
+#ifdef _OPENMP
+void handleMultithreadAbort();
+#else
+inline void handleMultithreadAbort(){}
+#endif
+
+// TODO: remove old code below
+#ifdef _OPENMP
+#define MULTITHREAD_FOR_CATCH_EXCEPTION(code) \
+    if (checkMultithreadAbort()) \
+    { \
+        continue; \
+    } \
+    try \
+    { \
+        code \
+    } \
+    catch (...) \
+    { \
+        setMultithreadAbort(); \
+    }
+#else
+#define MULTITHREAD_FOR_CATCH_EXCEPTION(code) code
+#endif
+
+#ifdef _OPENMP
+#define MULTITHREAD_TASK_CATCH_EXCEPTION(code) \
+    if (!checkMultithreadAbort()) \
+    { \
+        try \
+        { \
+            code \
+        } \
+        catch (...) \
+        { \
+            setMultithreadAbort(); \
+        } \
+    }
+#else
+#define MULTITHREAD_TASK_CATCH_EXCEPTION(code) code
+#endif
+
+}//namespace cura
+
+#endif // MULTITHREAD_OPENMP_H

src/pathOrderOptimizer.cpp

@@ -16,7 +16,7 @@ void PathOrderOptimizer::optimize()
     bool picked[polygons.size()];
     memset(picked, false, sizeof(bool) * polygons.size());/// initialized as falses
     
-    for (PolygonRef poly : polygons) /// find closest point to initial starting point within each polygon +initialize picked
+    for (ConstPolygonRef poly : polygons) /// find closest point to initial starting point within each polygon +initialize picked
     {
         int best = -1;
         float bestDist = std::numeric_limits<float>::infinity();
@@ -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);
@@ -102,15 +102,15 @@ int PathOrderOptimizer::getPolyStart(Point prev_point, int poly_idx)
 
 int PathOrderOptimizer::getClosestPointInPolygon(Point prev_point, int poly_idx)
 {
-    PolygonRef poly = polygons[poly_idx];
+    ConstPolygonRef poly = polygons[poly_idx];
 
     int best_point_idx = -1;
     float best_point_score = std::numeric_limits<float>::infinity();
     Point p0 = poly.back();
     for (unsigned int point_idx = 0; point_idx < poly.size(); point_idx++)
     {
-        Point& p1 = poly[point_idx];
-        Point& p2 = poly[(point_idx + 1) % poly.size()];
+        const Point& p1 = poly[point_idx];
+        const Point& p2 = poly[(point_idx + 1) % poly.size()];
         int64_t dist = vSize2(p1 - prev_point);
         float is_on_inside_corner_score = -LinearAlg2D::getAngleLeft(p0, p1, p2) / M_PI * 5000 * 5000; // prefer inside corners
         // this score is in the order of 5 mm
@@ -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;
-}
-
-
 /**
 *
 */
@@ -161,7 +143,7 @@ void LineOrderOptimizer::optimize()
     {
         int best_point_idx = -1;
         float best_point_dist = std::numeric_limits<float>::infinity();
-        PolygonRef poly = polygons[poly_idx];
+        ConstPolygonRef poly = polygons[poly_idx];
         for (unsigned int point_idx = 0; point_idx < poly.size(); point_idx++) /// get closest point from polygon
         {
             float dist = vSize2f(poly[point_idx] - startPoint);
@@ -217,13 +199,13 @@ void LineOrderOptimizer::optimize()
 
         if (best_line_idx > -1) /// should always be true; we should have been able to identify the best next polygon
         {
-            PolygonRef best_line = polygons[best_line_idx];
+            ConstPolygonRef best_line = polygons[best_line_idx];
             assert(best_line.size() == 2);
 
             int line_start_point_idx = polyStart[best_line_idx];
             int line_end_point_idx = line_start_point_idx * -1 + 1; /// 1 -> 0 , 0 -> 1
-            Point& line_start = best_line[line_start_point_idx];
-            Point& line_end = best_line[line_end_point_idx];
+            const Point& line_start = best_line[line_start_point_idx];
+            const Point& line_end = best_line[line_end_point_idx];
             prev_point = line_end;
             incoming_perpundicular_normal = turn90CCW(normal(line_end - line_start, 1000));
 
@@ -239,8 +221,8 @@ void LineOrderOptimizer::optimize()
 
 inline void LineOrderOptimizer::updateBestLine(unsigned int poly_idx, int& best, float& best_score, Point prev_point, Point incoming_perpundicular_normal)
 {
-    Point& p0 = polygons[poly_idx][0];
-    Point& p1 = polygons[poly_idx][1];
+    const Point& p0 = polygons[poly_idx][0];
+    const Point& p1 = polygons[poly_idx][1];
     float dot_score = getAngleScore(incoming_perpundicular_normal, p0, p1);
     { /// check distance to first point on line (0)
         float score = vSize2f(p0 - prev_point) + dot_score; // prefer 90 degree corners

src/pathOrderOptimizer.h

@@ -19,22 +19,29 @@ class PathOrderOptimizer
 public:
     EZSeamType type;
     Point startPoint; //!< A location near the prefered start location
-    std::vector<PolygonRef> polygons; //!< the parts of the layer (in arbitrary order)
+    Point z_seam_pos; //!< The position near where to create the z_seam (if \ref PathOrderOptimizer::type == 'back')
+    std::vector<ConstPolygonRef> 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)
     {
     }
 
     void addPolygon(PolygonRef polygon)
     {
-        this->polygons.push_back(polygon);
+        this->polygons.emplace_back(polygon);
     }
 
-    void addPolygons(Polygons& polygons)
+    void addPolygon(ConstPolygonRef polygon)
+    {
+        this->polygons.emplace_back(polygon);
+    }
+
+    void addPolygons(const Polygons& polygons)
     {
         for(unsigned int i=0;i<polygons.size(); i++)
             this->polygons.push_back(polygons[i]);
@@ -43,9 +50,15 @@ 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);
 
 
@@ -58,7 +71,7 @@ class LineOrderOptimizer
 {
 public:
     Point startPoint; //!< The location of the nozzle before starting to print the current layer
-    std::vector<PolygonRef> polygons; //!< the parts of the layer (in arbitrary order)
+    std::vector<ConstPolygonRef> 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
 
@@ -72,6 +85,11 @@ public:
         this->polygons.push_back(polygon);
     }
 
+    void addPolygon(ConstPolygonRef polygon)
+    {
+        this->polygons.push_back(polygon);
+    }
+
     void addPolygons(Polygons& polygons)
     {
         for(unsigned int i=0;i<polygons.size(); i++)

src/pathPlanning/Comb.cpp

@@ -12,19 +12,6 @@
 
 namespace cura {
 
-Polygons Comb::getCombOutlines()
-{
-    if (layer_nr >= 0)
-    {
-        bool include_helper_parts = false;
-        return storage.getLayerOutlines(layer_nr, include_helper_parts);
-    }
-    else
-    {
-        return storage.raftOutline;
-    }
-}
-
 LocToLineGrid& Comb::getOutsideLocToLine()
 {
     return *outside_loc_to_line;
@@ -39,14 +26,13 @@ Comb::Comb(SliceDataStorage& storage, int layer_nr, Polygons& comb_boundary_insi
 : storage(storage)
 , layer_nr(layer_nr)
 , offset_from_outlines(comb_boundary_offset) // between second wall and infill / other walls
-, max_move_inside_distance2(offset_from_outlines * 2 * offset_from_outlines * 2)
+, max_moveInside_distance2(offset_from_outlines * 2 * offset_from_outlines * 2)
 , offset_from_outlines_outside(travel_avoid_distance)
 , 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( comb_boundary_inside )
 , partsView_inside( boundary_inside.splitIntoPartsView() ) // WARNING !! changes the order of boundary_inside !!
-, outlines(getCombOutlines())
 , inside_loc_to_line(PolygonUtils::createLocToLineGrid(boundary_inside, comb_boundary_offset))
 , boundary_outside(
         [&storage, layer_nr, travel_avoid_distance]()
@@ -235,30 +221,15 @@ bool Comb::moveInside(bool is_inside, Point& dest_point, unsigned int& inside_po
 {
     if (is_inside)
     {
-        coord_t max_move_inside_distance2_here = std::numeric_limits<coord_t>::max(); // the distance which would make the moveInside fail
-        if (storage.getSettingAsCombingMode("retraction_combing") == cura::CombingMode::NO_SKIN)
-        { // if we perform no_skin combing, then a far move inside is likely a consequence of there meing skin in between the destination point and the inside comb boundary
-            // if we perform normal combing, then a far move inside is likely to be a consequence of sharp pointy segments in the layer part
-            max_move_inside_distance2_here = max_move_inside_distance2;
-        }
-        Point original_dest_point = dest_point;
-        ClosestPolygonPoint cpp = PolygonUtils::ensureInsideOrOutside(boundary_inside, dest_point, offset_extra_start_end, max_move_inside_distance2_here, &boundary_inside, inside_loc_to_line);
+        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;
         }
         else
         {
-            if (vSize2(dest_point - original_dest_point) > max_move_inside_distance2 // only check for collision with outlines for long moves
-                && PolygonUtils::polygonCollidesWithLineSegment(outlines, dest_point, original_dest_point))
-            {
-                return false;
-            }
-            else
-            {
-                inside_poly = cpp.poly_idx;
-                return true;
-            }
+            inside_poly = cpp.poly_idx;
+            return true;
         }
     }
     return false;
@@ -274,7 +245,7 @@ void Comb::Crossing::findCrossingInOrMid(const PartsView& partsView_inside, cons
         dest_part = partsView_inside.assemblePart(dest_part_idx);
 
         ClosestPolygonPoint boundary_crossing_point;
-        { // set [result] to a point on the destination part closest to close_to (but also a bit close to fest_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])
             {
@@ -361,7 +332,7 @@ bool Comb::Crossing::findOutside(const Polygons& outside, const Point close_to,
 }
 
 
-std::shared_ptr<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> Comb::Crossing::findBestCrossing(const Polygons& outside, const PolygonRef from, const Point estimated_start, const Point estimated_end, Comb& comber)
+std::shared_ptr<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> Comb::Crossing::findBestCrossing(const Polygons& outside, ConstPolygonRef from, const Point estimated_start, const Point estimated_end, Comb& comber)
 {
     ClosestPolygonPoint* best_in = nullptr;
     ClosestPolygonPoint* best_out = nullptr;

src/pathPlanning/Comb.h

@@ -48,7 +48,7 @@ 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)
-        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)
+        std::optional<ConstPolygonRef> 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
 
@@ -97,7 +97,7 @@ private:
          * \param comber[in] The combing calculator which has references to the offsets and boundaries to use in combing.
          * \return A pair of which the first is the crossing point on the inside boundary and the second the crossing point on the outside boundary
          */
-        std::shared_ptr<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> findBestCrossing(const Polygons& outside, const PolygonRef from, Point estimated_start, Point estimated_end, Comb& comber);
+        std::shared_ptr<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> findBestCrossing(const Polygons& outside, ConstPolygonRef from, Point estimated_start, Point estimated_end, Comb& comber);
     };
 
 
@@ -105,7 +105,7 @@ private:
     const int layer_nr; //!< The layer number for the layer for which to compute the outside boundary, when needed.
     
     const int64_t offset_from_outlines; //!< Offset from the boundary of a part to the comb path. (nozzle width / 2)
-    const int64_t max_move_inside_distance2; //!< Maximal distance of a point to the Comb::boundary_inside which is still to be considered inside. (very sharp corners not allowed :S)
+    const int64_t max_moveInside_distance2; //!< Maximal distance of a point to the Comb::boundary_inside which is still to be considered inside. (very sharp corners not allowed :S)
     const int64_t offset_from_outlines_outside; //!< Offset from the boundary of a part to a travel path which avoids it by this distance.
     const int64_t offset_from_inside_to_outside; //!< The sum of the offsets for the inside and outside boundary Comb::offset_from_outlines and Comb::offset_from_outlines_outside
     const int64_t max_crossing_dist2; //!< The maximal distance by which to cross the in_between area between inside and outside
@@ -114,19 +114,13 @@ private:
     static const int64_t offset_extra_start_end = 100; //!< Distance to move start point and end point toward eachother to extra avoid collision with the boundaries.
 
     const bool avoid_other_parts; //!< Whether to perform inverse combing a.k.a. avoid parts.
-
+    
     Polygons& boundary_inside; //!< The boundary within which to comb.
     PartsView partsView_inside; //!< Structured indices onto boundary_inside which shows which polygons belong to which part. 
-    Polygons outlines; //!< The actual boundary between the model and air
     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 outlines of the meshes or raft for this layer
-     */
-    Polygons getCombOutlines();
-
     /*!
      * Get the SparsePointGridInclusive mapping locations to line segments of the outside boundary. Calculate it when it hasn't been calculated yet.
      */

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:
+    const 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/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");

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

@@ -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);
@@ -345,6 +351,8 @@ 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")

src/settings/settings.h

@@ -105,6 +105,7 @@ enum class EFillMethod
     LINES,
     GRID,
     CUBIC,
+    CUBICSUBDIV,
     TETRAHEDRAL,
     TRIANGLES,
     CONCENTRIC,
@@ -230,12 +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;

src/skin.cpp

@@ -10,7 +10,16 @@
 namespace cura 
 {
 
-        
+
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateSkinAreas reads data from mesh.layers.parts[*].insets and writes to mesh.layers[n].parts[*].skin_parts
+ * generateSkinInsets only read/writes the skin_parts from the current layer.
+ *
+ * generateSkins therefore reads (depends on) data from mesh.layers[*].parts[*].insets and writes mesh.layers[n].parts[*].skin_parts
+ */
 void generateSkins(int layerNr, SliceMeshStorage& mesh, int downSkinCount, int upSkinCount, int wall_line_count, int innermost_wall_line_width, int insetCount, bool no_small_gaps_heuristic)
 {
     generateSkinAreas(layerNr, mesh, innermost_wall_line_width, downSkinCount, upSkinCount, wall_line_count, no_small_gaps_heuristic);
@@ -23,6 +32,12 @@ void generateSkins(int layerNr, SliceMeshStorage& mesh, int downSkinCount, int u
     }
 }
 
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateSkinAreas reads data from mesh.layers[*].parts[*].insets and writes to mesh.layers[n].parts[*].skin_parts
+ */
 void generateSkinAreas(int layer_nr, SliceMeshStorage& mesh, const int innermost_wall_line_width, int downSkinCount, int upSkinCount, int wall_line_count, bool no_small_gaps_heuristic)
 {
     SliceLayer& layer = mesh.layers[layer_nr];
@@ -106,7 +121,12 @@ void generateSkinAreas(int layer_nr, SliceMeshStorage& mesh, const int innermost
     }
 }
 
-
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateSkinInsets only read/writes the skin_parts from the current layer.
+ */
 void generateSkinInsets(SliceLayerPart* part, const int wall_line_width, int insetCount)
 {
     if (insetCount == 0)
@@ -139,6 +159,12 @@ void generateSkinInsets(SliceLayerPart* part, const int wall_line_width, int ins
     }
 }
 
+/*
+ * This function is executed in a parallel region based on layer_nr.
+ * When modifying make sure any changes does not introduce data races.
+ *
+ * generateInfill read mesh.layers[n].parts[*].{insets,skin_parts,boundingBox} and write mesh.layers[n].parts[*].infill_area
+ */
 void generateInfill(int layerNr, SliceMeshStorage& mesh, const int innermost_wall_line_width, int infill_skin_overlap, int wall_line_count)
 {
     SliceLayer& layer = mesh.layers[layerNr];
@@ -146,6 +172,7 @@ void generateInfill(int layerNr, SliceMeshStorage& mesh, const int innermost_wal
     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)
     {

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
 {
@@ -30,7 +35,7 @@ void SliceLayer::getOutlines(Polygons& result, bool external_polys_only) const
     {
         if (external_polys_only)
         {
-            result.add(const_cast<SliceLayerPart&>(part).outline.outerPolygon()); // TODO: make a const version of outerPolygon()
+            result.add(part.outline.outerPolygon());
         }
         else 
         {
@@ -52,12 +57,12 @@ void SliceLayer::getSecondOrInnermostWalls(Polygons& layer_walls) const
     {
         // we want the 2nd inner walls
         if (part.insets.size() >= 2) {
-            layer_walls.add(const_cast<SliceLayerPart&>(part).insets[1]); // TODO const cast!
+            layer_walls.add(part.insets[1]);
             continue;
         }
         // but we'll also take the inner wall if the 2nd doesn't exist
         if (part.insets.size() == 1) {
-            layer_walls.add(const_cast<SliceLayerPart&>(part).insets[0]); // TODO const cast!
+            layer_walls.add(part.insets[0]);
             continue;
         }
         // offset_from_outlines was so large that it completely destroyed our isle,
@@ -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;
@@ -106,37 +119,11 @@ SliceDataStorage::SliceDataStorage(MeshGroup* meshgroup) : SettingsMessenger(mes
     raft_surface_config(PrintFeatureType::SupportInterface),
     support_config(PrintFeatureType::Support),
     support_skin_config(PrintFeatureType::SupportInterface),
-    max_print_height_second_to_last_extruder(-1)
+    max_print_height_second_to_last_extruder(-1),
+    primeTower(*this)
 {
 }
 
-SliceLayerPart* SliceDataStorage::getPartInside(int layer_nr, Point location)
-{
-    if (layer_nr >= 0)
-    {
-        for (SliceMeshStorage& mesh : meshes)
-        {
-            if ((unsigned int)layer_nr >= mesh.layers.size())
-            {
-                continue;
-            }
-            SliceLayer& layer = mesh.layers[layer_nr];
-            for (SliceLayerPart& part : layer.parts)
-            {
-                if (part.outline.inside(location))
-                {
-                    return &part;
-                }
-            }
-        }
-        return nullptr;
-    }
-    else
-    {
-        return nullptr;
-    }
-}
-
 Polygons SliceDataStorage::getLayerOutlines(int layer_nr, bool include_helper_parts, bool external_polys_only) const
 {
     if (layer_nr < 0 && layer_nr < -Raft::getFillerLayerCount(*this))
@@ -176,7 +163,7 @@ Polygons SliceDataStorage::getLayerOutlines(int layer_nr, bool include_helper_pa
                 }
                 const SliceLayer& layer = mesh.layers[layer_nr];
                 layer.getOutlines(total, external_polys_only);
-                if (const_cast<SliceMeshStorage&>(mesh).getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL) // TODO: make all getSetting functions const??
+                if (mesh.getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL)
                 {
                     total = total.unionPolygons(layer.openPolyLines.offsetPolyLine(100));
                 }
@@ -189,7 +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;
     }
@@ -217,7 +207,7 @@ Polygons SliceDataStorage::getLayerSecondOrInnermostWalls(int layer_nr, bool inc
             {
                 const SliceLayer& layer = mesh.layers[layer_nr];
                 layer.getSecondOrInnermostWalls(total);
-                if (const_cast<SliceMeshStorage&>(mesh).getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL) // TODO: make getSetting const? make settings.setting_values mapping mutable??
+                if (mesh.getSettingAsSurfaceMode("magic_mesh_surface_mode") != ESurfaceMode::NORMAL)
                 {
                     total = total.unionPolygons(layer.openPolyLines.offsetPolyLine(100));
                 }
@@ -230,7 +220,10 @@ 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;
     }

src/sliceDataStorage.h

@@ -143,6 +143,8 @@ public:
 };
 /******************/
 
+class SubDivCube; // forward declaration to prevent dependency loop
+
 class SliceMeshStorage : public SettingsMessenger // passes on settings from a Mesh object
 {
 public:
@@ -153,20 +155,27 @@ public:
     GCodePathConfig inset0_config;
     GCodePathConfig insetX_config;
     GCodePathConfig skin_config;
+    GCodePathConfig perimeter_gap_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)
+    , perimeter_gap_config(PrintFeatureType::Skin)
+    , base_subdiv_cube(nullptr)
     {
         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
@@ -239,15 +248,6 @@ public:
     {
     }
 
-    /*!
-     * Check in which part \p location lies, if in any.
-     * 
-     * \param layer_nr The layer for which to check
-     * \param location The location to check
-     * \return The part in which \p location lie, or nullptr, if it's outside all parts.
-     */
-    SliceLayerPart* getPartInside(int layer_nr, Point location);
-
     /*!
      * Get all outlines within a given layer.
      * 

src/slicer.cpp

@@ -8,6 +8,7 @@
 #include "utils/SparsePointGridInclusive.h"
 
 #include "slicer.h"
+#include "multithreadOpenMP.h"
 
 
 namespace cura {
@@ -216,7 +217,7 @@ SlicerLayer::findPossibleStitches(
     //   insert the starts of the polylines).
     for(unsigned int polyline_0_idx = 0; polyline_0_idx < open_polylines.size(); polyline_0_idx++)
     {
-        const PolygonRef polyline_0 = open_polylines[polyline_0_idx];
+        ConstPolygonRef polyline_0 = open_polylines[polyline_0_idx];
 
         if (polyline_0.size() < 1) continue;
 
@@ -231,7 +232,7 @@ SlicerLayer::findPossibleStitches(
     {
         for(unsigned int polyline_0_idx = 0; polyline_0_idx < open_polylines.size(); polyline_0_idx++)
         {
-            const PolygonRef polyline_0 = open_polylines[polyline_0_idx];
+            ConstPolygonRef polyline_0 = open_polylines[polyline_0_idx];
 
             if (polyline_0.size() < 1) continue;
 
@@ -245,7 +246,7 @@ SlicerLayer::findPossibleStitches(
     // search for nearby end points
     for(unsigned int polyline_1_idx = 0; polyline_1_idx < open_polylines.size(); polyline_1_idx++)
     {
-        const PolygonRef polyline_1 = open_polylines[polyline_1_idx];
+        ConstPolygonRef polyline_1 = open_polylines[polyline_1_idx];
 
         if (polyline_1.size() < 1) continue;
 
@@ -589,7 +590,7 @@ void SlicerLayer::stitch_extensive(Polygons& open_polylines)
             {
                 if (best_result.pointIdxA == best_result.pointIdxB)
                 {
-                    polygons.add(open_polylines[best_polyline_1_idx]);
+                    polygons.add(PolygonRef{open_polylines[best_polyline_1_idx]});
                     open_polylines[best_polyline_1_idx].clear();
                 }
                 else if (best_result.AtoB)
@@ -604,9 +605,9 @@ void SlicerLayer::stitch_extensive(Polygons& open_polylines)
                 else
                 {
                     unsigned int n = polygons.size();
-                    polygons.add(open_polylines[best_polyline_1_idx]);
+                    polygons.add(PolygonRef{open_polylines[best_polyline_1_idx]});
                     for(unsigned int j = best_result.pointIdxB; j != best_result.pointIdxA; j = (j + 1) % polygons[best_result.polygonIdx].size())
-                        polygons[n].add(polygons[best_result.polygonIdx][j]);
+                        PolygonRef{polygons[n]}.add(polygons[best_result.polygonIdx][j]);
                     open_polylines[best_polyline_1_idx].clear();
                 }
             }
@@ -615,7 +616,7 @@ void SlicerLayer::stitch_extensive(Polygons& open_polylines)
                 if (best_result.pointIdxA == best_result.pointIdxB)
                 {
                     for(unsigned int n=0; n<open_polylines[best_polyline_1_idx].size(); n++)
-                        open_polylines[best_polyline_2_idx].add(open_polylines[best_polyline_1_idx][n]);
+                        PolygonRef{open_polylines[best_polyline_2_idx]}.add(open_polylines[best_polyline_1_idx][n]);
                     open_polylines[best_polyline_1_idx].clear();
                 }
                 else if (best_result.AtoB)
@@ -624,17 +625,17 @@ void SlicerLayer::stitch_extensive(Polygons& open_polylines)
                     for(unsigned int n = best_result.pointIdxA; n != best_result.pointIdxB; n = (n + 1) % polygons[best_result.polygonIdx].size())
                         poly.add(polygons[best_result.polygonIdx][n]);
                     for(unsigned int n=poly.size()-1;int(n) >= 0; n--)
-                        open_polylines[best_polyline_2_idx].add(poly[n]);
+                        PolygonRef{open_polylines[best_polyline_2_idx]}.add(poly[n]);
                     for(unsigned int n=0; n<open_polylines[best_polyline_1_idx].size(); n++)
-                        open_polylines[best_polyline_2_idx].add(open_polylines[best_polyline_1_idx][n]);
+                        PolygonRef{open_polylines[best_polyline_2_idx]}.add(open_polylines[best_polyline_1_idx][n]);
                     open_polylines[best_polyline_1_idx].clear();
                 }
                 else
                 {
                     for(unsigned int n = best_result.pointIdxB; n != best_result.pointIdxA; n = (n + 1) % polygons[best_result.polygonIdx].size())
-                        open_polylines[best_polyline_2_idx].add(polygons[best_result.polygonIdx][n]);
+                        PolygonRef{open_polylines[best_polyline_2_idx]}.add(polygons[best_result.polygonIdx][n]);
                     for(unsigned int n = open_polylines[best_polyline_1_idx].size() - 1; int(n) >= 0; n--)
-                        open_polylines[best_polyline_2_idx].add(open_polylines[best_polyline_1_idx][n]);
+                        PolygonRef{open_polylines[best_polyline_2_idx]}.add(open_polylines[best_polyline_1_idx][n]);
                     open_polylines[best_polyline_1_idx].clear();
                 }
             }
@@ -759,7 +760,7 @@ 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);
         }
     }
 
@@ -887,10 +888,15 @@ Slicer::Slicer(Mesh* mesh, int initial, int thickness, int slice_layer_count, bo
         }
     }
     log("slice of mesh took %.3f seconds\n",slice_timer.restart());
-    for(unsigned int layer_nr=0; layer_nr<layers.size(); layer_nr++)
-    {
-        layers[layer_nr].makePolygons(mesh, keep_none_closed, extensive_stitching);
-    }
+
+    auto& layers_ref = layers;
+#pragma omp parallel for default(none) shared(mesh,layers_ref) firstprivate(keep_none_closed, extensive_stitching)
+    for(unsigned int layer_nr=0; layer_nr<layers_ref.size(); layer_nr++)
+    { MULTITHREAD_FOR_CATCH_EXCEPTION(
+        layers_ref[layer_nr].makePolygons(mesh, keep_none_closed, extensive_stitching);
+    )}
+    handleMultithreadAbort();
+
     mesh->expandXY(mesh->getSettingInMicrons("xy_offset"));
     log("slice make polygons took %.3f seconds\n",slice_timer.restart());
 }

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>
@@ -87,6 +90,7 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int l
         storage.support.supportLayers.resize(layer_count);
     }
 
+    // generate support areas
     for (unsigned int mesh_idx = 0; mesh_idx < storage.meshes.size(); mesh_idx++)
     {
         SliceMeshStorage& mesh = storage.meshes[mesh_idx];
@@ -97,25 +101,33 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int l
         std::vector<Polygons> supportAreas;
         supportAreas.resize(layer_count, Polygons());
         generateSupportAreas(storage, mesh_idx, layer_count, supportAreas);
-        
-        if (mesh.getSettingBoolean("support_interface_enable"))
+
+        for (unsigned int layer_idx = 0; layer_idx < layer_count; layer_idx++)
         {
-            generateSupportInterface(storage, mesh, supportAreas, layer_count);
-        }
-        else 
-        {
-            for (unsigned int layer_idx = 0; layer_idx < layer_count ; layer_idx++)
-            {
-                storage.support.supportLayers[layer_idx].supportAreas.add(supportAreas[layer_idx]);
-            }
+            storage.support.supportLayers[layer_idx].supportAreas.add(supportAreas[layer_idx]);
         }
     }
-    
+
     for (unsigned int layer_idx = 0; layer_idx < layer_count ; layer_idx++)
     {
         Polygons& support_areas = storage.support.supportLayers[layer_idx].supportAreas;
         support_areas = support_areas.unionPolygons();
     }
+
+    // handle support interface
+    for (unsigned int mesh_idx = 0; mesh_idx < storage.meshes.size(); mesh_idx++)
+    {
+        SliceMeshStorage& mesh = storage.meshes[mesh_idx];
+        if (mesh.getSettingBoolean("infill_mesh") || mesh.getSettingBoolean("anti_overhang_mesh"))
+        {
+            continue;
+        }
+
+        if (mesh.getSettingBoolean("support_interface_enable"))
+        {
+            generateSupportInterface(storage, mesh, layer_count);
+        }
+    }
 }
 
 /* 
@@ -274,8 +286,8 @@ 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;
         
         
@@ -295,7 +307,7 @@ 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));
             }
         }
 
@@ -338,6 +350,17 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
         }
     }
 
+    //Enforce top Z distance.
+    if (layerZdistanceTop > 1)
+    {
+        // 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 - 1); layer_idx++)
+        {
+            supportAreas[layer_idx] = supportAreas[layer_idx].difference(storage.getLayerOutlines(layer_idx + layerZdistanceTop - 1, 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--)
     {
@@ -373,7 +396,10 @@ std::pair<Polygons, Polygons> AreaSupport::computeBasicAndFullOverhang(const Sli
     Polygons basic_overhang = supportLayer_supportee.difference(supportLayer_supported);
 
     const SupportLayer& support_layer = storage.support.supportLayers[layer_idx];
-    basic_overhang = basic_overhang.difference(support_layer.anti_overhang);
+    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);
@@ -482,7 +508,7 @@ void AreaSupport::handleTowers(
         {
             supportLayer_this = supportLayer_this.unionPolygons(tower_roof);
 
-            if (tower_roof[0].area() < supportTowerDiameter * supportTowerDiameter)
+            if (PolygonRef{tower_roof[0]}.area() < supportTowerDiameter * supportTowerDiameter)
             {
                 tower_roof = tower_roof.offset(towerRoofExpansionDistance);
             }
@@ -542,7 +568,7 @@ void AreaSupport::handleWallStruts(
 }
 
 
-void AreaSupport::generateSupportInterface(SliceDataStorage& storage, const SliceMeshStorage& mesh, std::vector<Polygons>& support_areas, const unsigned int layer_count)
+void AreaSupport::generateSupportInterface(SliceDataStorage& storage, const SliceMeshStorage& mesh, const unsigned int layer_count)
 {
     const unsigned int roof_layer_count = round_divide(mesh.getSettingInMicrons("support_roof_height"), storage.getSettingInMicrons("layer_height"));
     const unsigned int bottom_layer_count = round_divide(mesh.getSettingInMicrons("support_bottom_height"), storage.getSettingInMicrons("layer_height"));
@@ -559,44 +585,41 @@ void AreaSupport::generateSupportInterface(SliceDataStorage& storage, const Slic
 
         const unsigned int top_layer_idx_above = layer_idx + roof_layer_count + z_distance_top;
         const unsigned int bottom_layer_idx_below = std::max(0, int(layer_idx) - int(bottom_layer_count) - int(z_distance_bottom));
-        if (top_layer_idx_above < supportLayers.size())
+        if (top_layer_idx_above >= supportLayers.size())
         {
-            Polygons roofs;
-            if (roof_layer_count > 0)
-            {
-                Polygons model;
-                const unsigned int n_scans = std::max(1u, (roof_layer_count - 1) / skip_layer_count);
-                const float z_skip = std::max(1.0f, float(roof_layer_count - 1) / float(n_scans));
-                for (float layer_idx_above = top_layer_idx_above; layer_idx_above > layer_idx + z_distance_top; layer_idx_above -= z_skip)
-                {
-                    const Polygons outlines_above = mesh.layers[std::round(layer_idx_above)].getOutlines();
-                    model = model.unionPolygons(outlines_above);
-                }
-                roofs = support_areas[layer_idx].intersection(model);
-            }
-            Polygons bottoms;
-            if (bottom_layer_count > 0)
-            {
-                Polygons model;
-                const unsigned int n_scans = std::max(1u, (bottom_layer_count - 1) / skip_layer_count);
-                const float z_skip = std::max(1.0f, float(bottom_layer_count - 1) / float(n_scans));
-                for (float layer_idx_below = bottom_layer_idx_below; std::round(layer_idx_below) < (int)(layer_idx - z_distance_bottom); layer_idx_below += z_skip)
-                {
-                    const Polygons outlines_below = mesh.layers[std::round(layer_idx_below)].getOutlines();
-                    model = model.unionPolygons(outlines_below);
-                }
-                bottoms = support_areas[layer_idx].intersection(model);
-            }
-            // expand skin a bit so that we're sure it's not too thin to be printed.
-            Polygons skin = roofs.unionPolygons(bottoms).offset(interface_line_width).intersection(support_areas[layer_idx]);
-            skin.removeSmallAreas(1.0);
-            layer.skin.add(skin);
-            layer.supportAreas.add(support_areas[layer_idx].difference(layer.skin));
+            continue;
         }
-        else 
+        Polygons roofs;
+        if (roof_layer_count > 0)
         {
-            layer.skin.add(support_areas[layer_idx]);
+            Polygons model;
+            const unsigned int n_scans = std::max(1u, (roof_layer_count - 1) / skip_layer_count);
+            const float z_skip = std::max(1.0f, float(roof_layer_count - 1) / float(n_scans));
+            for (float layer_idx_above = top_layer_idx_above; layer_idx_above > layer_idx + z_distance_top; layer_idx_above -= z_skip)
+            {
+                const Polygons outlines_above = mesh.layers[std::round(layer_idx_above)].getOutlines();
+                model = model.unionPolygons(outlines_above);
+            }
+            roofs = layer.supportAreas.intersection(model);
         }
+        Polygons bottoms;
+        if (bottom_layer_count > 0)
+        {
+            Polygons model;
+            const unsigned int n_scans = std::max(1u, (bottom_layer_count - 1) / skip_layer_count);
+            const float z_skip = std::max(1.0f, float(bottom_layer_count - 1) / float(n_scans));
+            for (float layer_idx_below = bottom_layer_idx_below; std::round(layer_idx_below) < (int)(layer_idx - z_distance_bottom); layer_idx_below += z_skip)
+            {
+                const Polygons outlines_below = mesh.layers[std::round(layer_idx_below)].getOutlines();
+                model = model.unionPolygons(outlines_below);
+            }
+            bottoms = layer.supportAreas.intersection(model);
+        }
+        // expand skin a bit so that we're sure it's not too thin to be printed.
+        Polygons skin = roofs.unionPolygons(bottoms).offset(interface_line_width).intersection(layer.supportAreas);
+        skin.removeSmallAreas(1.0);
+        layer.skin.add(skin);
+        layer.supportAreas = layer.supportAreas.difference(layer.skin);
     }
 }
 

src/support.h

@@ -36,10 +36,9 @@ private:
      * 
      * \param storage Output storage: support area + support skin area output
      * \param mesh The mesh to generate support skins for.
-     * \param support_areas The basic support areas for the current mesh
      * \param layer_count The number of layers in this mesh group.
      */
-    static void generateSupportInterface(SliceDataStorage& storage, const SliceMeshStorage& mesh, std::vector<Polygons>& support_areas, const unsigned int layer_count);
+    static void generateSupportInterface(SliceDataStorage& storage, const SliceMeshStorage& mesh, const unsigned int layer_count);
 
     /*!
      * Join current support layer with the support of the layer above, (make support conical) and perform smoothing etc operations.

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/AABB.cpp

@@ -24,7 +24,7 @@ AABB::AABB(const Polygons& polys)
     calculate(polys);
 }
 
-AABB::AABB(const PolygonRef poly)
+AABB::AABB(const PolygonRef& poly)
 : min(POINT_MAX, POINT_MAX), max(POINT_MIN, POINT_MIN)
 {
     calculate(poly);
@@ -43,7 +43,7 @@ void AABB::calculate(const Polygons& polys)
     }
 }
 
-void AABB::calculate(const PolygonRef poly)
+void AABB::calculate(const PolygonRef& poly)
 {
     min = Point(POINT_MAX, POINT_MAX);
     max = Point(POINT_MIN, POINT_MIN);

src/utils/AABB.h

@@ -20,10 +20,10 @@ public:
     AABB(); //!< initializes with invalid min and max
     AABB(Point& min, Point& max); //!< initializes with given min and max
     AABB(const Polygons& polys); //!< Computes the boundary box for the given polygons
-    AABB(const PolygonRef poly); //!< Computes the boundary box for the given polygons
+    AABB(const PolygonRef& poly); //!< Computes the boundary box for the given polygons
 
     void calculate(const Polygons& polys); //!< Calculates the aabb for the given polygons (throws away old min and max data of this aabb)
-    void calculate(const PolygonRef poly); //!< Calculates the aabb for the given polygon (throws away old min and max data of this aabb)
+    void calculate(const PolygonRef& poly); //!< Calculates the aabb for the given polygon (throws away old min and max data of this aabb)
 
     /*!
      * Check whether this aabb overlaps with another.

src/utils/AABB3D.cpp

@@ -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/ListPolyIt.cpp

@@ -19,12 +19,12 @@ void ListPolyIt::convertPolygonsToLists(Polygons& polys, ListPolygons& result)
     }
 }
 
-void ListPolyIt::convertPolygonToList(PolygonRef poly, ListPolygon& result)
+void ListPolyIt::convertPolygonToList(const PolygonRef& poly, ListPolygon& result)
 {
 #ifdef DEBUG
     Point last = poly.back();
 #endif // DEBUG
-    for (Point& p : poly) 
+    for (const Point& p : poly)
     {
         result.push_back(p);
 #ifdef DEBUG

src/utils/ListPolyIt.h

@@ -101,7 +101,7 @@ public:
      * \param polys The polygons to convert
      * \param result The converted polygons
      */
-    static void convertPolygonToList(PolygonRef poly, ListPolygon& result);
+    static void convertPolygonToList(const PolygonRef& poly, ListPolygon& result);
     /*!
      * Convert ListPolygons to Polygons
      * 

src/utils/PolygonsPointIndex.h

@@ -46,7 +46,7 @@ public:
     /*!
      * Get the polygon to which this PolygonsPointIndex refers
      */
-    const PolygonRef getPolygon() const
+    const ConstPolygonRef getPolygon() const
     {
         return (*polygons)[poly_idx];
     }

src/utils/SVG.h

@@ -93,7 +93,7 @@ public:
         {
             for(unsigned int j=0;j<parts.size();j++)
             {
-                Polygon poly = parts[j];
+                Polygon poly = PolygonRef{parts[j]};
                 fprintf(out, "<polygon points=\"");
                 for(Point& p : poly)
                 {
@@ -130,9 +130,9 @@ public:
         }
     }
 
-    void writePoints(PolygonRef poly, bool write_coords=false, int size = 5, Color color = Color::BLACK)
+    void writePoints(ConstPolygonRef poly, bool write_coords=false, int size = 5, Color color = Color::BLACK)
     {
-        for (Point& p : poly)
+        for (const Point& p : poly)
         {
             writePoint(p, write_coords, size, color);
         }
@@ -209,12 +209,12 @@ public:
     }
     void writePolygons(const Polygons& polys, Color color = Color::BLACK)
     {
-        for (const PolygonRef poly : const_cast<Polygons&>(polys))
+        for (ConstPolygonRef poly : polys)
         {
             writePolygon(poly, color);
         }
     }
-    void writePolygon(const PolygonRef poly, Color color = Color::BLACK)
+    void writePolygon(ConstPolygonRef poly, Color color = Color::BLACK)
     {
         Point p0 = poly.back();
         for (Point p1 : poly)

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/optional.h

@@ -45,7 +45,7 @@ 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...))
     {
     }
@@ -62,7 +62,7 @@ public:
      * \param null_ptr exactly [nullptr]
      * \return this
      */
-    optional& operator=(std::nullptr_t null_ptr)
+    optional& operator=(std::nullptr_t)
     {
         if (instance)
         {
@@ -121,12 +121,12 @@ public:
     }
     constexpr T* operator->() const
     {
-        assert(instance && "instance should be instatiated!");
+        assert(instance && "Instance should be instantiated!");
         return instance;
     }
     constexpr T& operator*() const&
     {
-        assert(instance && "instance should be instatiated!");
+        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

@@ -8,6 +8,23 @@
 namespace cura 
 {
 
+/*
+ * Implementation of offset polygon used by PolygonRef and ConstPolygonRef
+ *
+ * \param ret_paths[out] where the offset polygon is stored.
+ * \param path the path to be offset.
+ * \param distance the distance to offset path.
+ * \param joinType See ClipperLib documentation.
+ * \param miter_limit See ClipperLib documentation.
+ */
+inline void PolygonRef_offset_impl(ClipperLib::Paths& ret_path, const ClipperLib::Path& path, int distance, ClipperLib::JoinType join_type, double miter_limit)
+{
+    ClipperLib::ClipperOffset clipper(miter_limit, 10.0);
+    clipper.AddPath(path, join_type, ClipperLib::etClosedPolygon);
+    clipper.MiterLimit = miter_limit;
+    clipper.Execute(ret_path, distance);
+}
+
 bool PolygonRef::shorterThan(int64_t check_length) const
 {
     const PolygonRef& polygon = *this;
@@ -27,7 +44,7 @@ bool PolygonRef::shorterThan(int64_t check_length) const
 
 bool PolygonRef::_inside(Point p, bool border_result) const
 {
-    PolygonRef thiss = *this;
+    const PolygonRef& thiss = *this;
     if (size() < 1)
     {
         return false;
@@ -97,27 +114,6 @@ bool Polygons::inside(Point p, bool border_result) const
     return (poly_count_inside % 2) == 1;
 }
 
-bool PolygonsPart::inside(Point p, bool border_result) const
-{
-    if (size() < 1)
-    {
-        return false;
-    }
-    if (!(*this)[0].inside(p, border_result))
-    {
-        return false;
-    }
-    for (unsigned int n = 1; n < paths.size(); n++)
-    {
-        if ((*this)[n].inside(p, !border_result))
-        {
-            return false;
-        }
-    }
-    return true;
-}
-
-
 bool Polygons::insideOld(Point p, bool border_result) const
 {
     const Polygons& thiss = *this;
@@ -224,10 +220,7 @@ Polygons Polygons::offset(int distance, ClipperLib::JoinType join_type, double m
 Polygons PolygonRef::offset(int distance, ClipperLib::JoinType joinType, double miter_limit) const
 {
     Polygons ret;
-    ClipperLib::ClipperOffset clipper(miter_limit, 10.0);
-    clipper.AddPath(*path, joinType, ClipperLib::etClosedPolygon);
-    clipper.MiterLimit = miter_limit;
-    clipper.Execute(ret.paths, distance);
+    PolygonRef_offset_impl(ret.paths, *path, distance, joinType, miter_limit);
     return ret;
 }
 
@@ -973,7 +966,7 @@ Polygons Polygons::smooth_outward(float max_angle, int shortcut_length)
     return ret;
 }
 
-void PolygonRef::smooth(int remove_length, PolygonRef result)
+inline void PolygonRef_smooth_impl(const ClipperLib::Path& thiss, int remove_length, ClipperLib::Path* poly)
 {
 // a typical zigzag with the middle part to be removed by removing (1) :
 //
@@ -988,9 +981,7 @@ void PolygonRef::smooth(int remove_length, PolygonRef result)
 //          |
 //          |
 //          0
-    PolygonRef& thiss = *this;
-    ClipperLib::Path* poly = result.path;
-    if (size() > 0)
+    if (thiss.size() > 0)
     {
         poly->push_back(thiss[0]);
     }
@@ -1024,11 +1015,11 @@ void PolygonRef::smooth(int remove_length, PolygonRef result)
     Point v02T = turn90CCW(v02);
     int64_t v02_size = vSize(v02);
     bool force_push = false;
-    for (unsigned int poly_idx = 1; poly_idx < size(); poly_idx++)
+    for (unsigned int poly_idx = 1; poly_idx < thiss.size(); poly_idx++)
     {
         const Point& p1 = thiss[poly_idx];
-        const Point& p2 = thiss[(poly_idx + 1) % size()];
-        const Point& p3 = thiss[(poly_idx + 2) % size()];
+        const Point& p2 = thiss[(poly_idx + 1) % thiss.size()];
+        const Point& p3 = thiss[(poly_idx + 2) % thiss.size()];
         // v02 computed in last iteration
         // v02_size as well
         const Point v12 = p2 - p1;
@@ -1057,12 +1048,22 @@ void PolygonRef::smooth(int remove_length, PolygonRef result)
     }
 }
 
-Polygons Polygons::smooth(int remove_length)
+void PolygonRef::smooth(int remove_length, PolygonRef result) const
+{
+    PolygonRef_smooth_impl(*path, remove_length, result.path);
+}
+
+void ConstPolygonRef::smooth(int remove_length, PolygonRef result) const
+{
+    PolygonRef_smooth_impl(*path, remove_length, &(*result));
+}
+
+Polygons Polygons::smooth(int remove_length) const
 {
     Polygons ret;
     for (unsigned int p = 0; p < size(); p++)
     {
-        PolygonRef poly(paths[p]);
+        ConstPolygonRef poly(paths[p]);
         if (poly.size() < 3)
         {
             continue;
@@ -1082,23 +1083,21 @@ Polygons Polygons::smooth(int remove_length)
     return ret;
 }
 
-void PolygonRef::smooth2(int remove_length, PolygonRef result)
+inline void PolygonRef_smooth2_impl(const ClipperLib::Path& thiss, int remove_length, ClipperLib::Path* poly)
 {
-    PolygonRef& thiss = *this;
-    ClipperLib::Path* poly = result.path;
-    if (size() > 0)
+    if (thiss.size() > 0)
     {
         poly->push_back(thiss[0]);
     }
-    for (unsigned int poly_idx = 1; poly_idx < size(); poly_idx++)
+    for (unsigned int poly_idx = 1; poly_idx < thiss.size(); poly_idx++)
     {
-        Point& last = thiss[poly_idx - 1];
-        Point& now = thiss[poly_idx];
-        Point& next = thiss[(poly_idx + 1) % size()];
-        if (shorterThen(last - now, remove_length) && shorterThen(now - next, remove_length)) 
+        const Point& last = thiss[poly_idx - 1];
+        const Point& now = thiss[poly_idx];
+        const Point& next = thiss[(poly_idx + 1) % thiss.size()];
+        if (shorterThen(last - now, remove_length) && shorterThen(now - next, remove_length))
         {
             poly_idx++; // skip the next line piece (dont escalate the removal of edges)
-            if (poly_idx < size())
+            if (poly_idx < thiss.size())
             {
                 poly->push_back(thiss[poly_idx]);
             }
@@ -1110,12 +1109,22 @@ void PolygonRef::smooth2(int remove_length, PolygonRef result)
     }
 }
 
-Polygons Polygons::smooth2(int remove_length, int min_area)
+void PolygonRef::smooth2(int remove_length, PolygonRef result) const
+{
+    PolygonRef_smooth2_impl(*path, remove_length, result.path);
+}
+
+void ConstPolygonRef::smooth2(int remove_length, PolygonRef result) const
+{
+    PolygonRef_smooth2_impl(*path, remove_length, &(*result));
+}
+
+Polygons Polygons::smooth2(int remove_length, int min_area) const
 {
     Polygons ret;
     for (unsigned int p = 0; p < size(); p++)
     {
-        PolygonRef poly(paths[p]);
+        ConstPolygonRef poly(paths[p]);
         if (poly.size() == 0)
         {
             continue;
@@ -1137,6 +1146,13 @@ Polygons Polygons::smooth2(int remove_length, int min_area)
     return ret;
 }
 
+Polygons ConstPolygonRef::offset(int distance, ClipperLib::JoinType joinType, double miter_limit) const
+{
+    Polygons ret;
+    PolygonRef_offset_impl(ret.paths, *path, distance, joinType, miter_limit);
+    return ret;
+}
+
 std::vector<PolygonsPart> Polygons::splitIntoParts(bool unionAll) const
 {
     std::vector<PolygonsPart> ret;
@@ -1158,10 +1174,10 @@ void Polygons::splitIntoParts_processPolyTreeNode(ClipperLib::PolyNode* node, st
     {
         ClipperLib::PolyNode* child = node->Childs[n];
         PolygonsPart part;
-        part.add(child->Contour);
+        part.add(ConstPolygonRef{child->Contour});
         for(int i=0; i<child->ChildCount(); i++)
         {
-            part.add(child->Childs[i]->Contour);
+            part.add(ConstPolygonRef{child->Childs[i]->Contour});
             splitIntoParts_processPolyTreeNode(child->Childs[i], ret);
         }
         ret.push_back(part);
@@ -1193,7 +1209,7 @@ PolygonsPart PartsView::assemblePart(unsigned int part_idx) const
     {
         for (unsigned int poly_idx_ff : partsView[part_idx])
         {
-            ret.add(polygons[poly_idx_ff]);
+            ret.add(PolygonRef{polygons[poly_idx_ff]});
         }
     }
     return ret;
@@ -1236,11 +1252,11 @@ void Polygons::splitIntoPartsView_processPolyTreeNode(PartsView& partsView, Poly
         partsView.emplace_back();
         unsigned int pos = partsView.size() - 1;
         partsView[pos].push_back(reordered.size());
-        reordered.add(child->Contour);
+        reordered.add(ConstPolygonRef{child->Contour}); //TODO: should this steal the internal representation for speed?
         for(int i = 0; i < child->ChildCount(); i++)
         {
             partsView[pos].push_back(reordered.size());
-            reordered.add(child->Childs[i]->Contour);
+            reordered.add(ConstPolygonRef{child->Childs[i]->Contour});
             splitIntoPartsView_processPolyTreeNode(partsView, reordered, child->Childs[i]);
         }
     }

src/utils/polygon.h

@@ -11,6 +11,8 @@
 #include <limits> // int64_t.min
 #include <list>
 
+#include <initializer_list>
+
 #include "intpoint.h"
 
 #define CHECK_POLY_ACCESS
@@ -41,6 +43,12 @@ class PolygonRef
     : path(nullptr)
     {}
 public:
+    PolygonRef(PolygonRef& polygon)
+    :path{polygon.path}
+    {}
+    PolygonRef(PolygonRef&& polygon)
+    :path{polygon.path}
+    {}
     PolygonRef(ClipperLib::Path& polygon)
     : path(&polygon)
     {}
@@ -52,7 +60,7 @@ public:
 
     Point& operator[] (unsigned int index) const
     {
-        POLY_ASSERT(index < size() && index >= 0);
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
         return (*path)[index];
     }
 
@@ -76,7 +84,9 @@ public:
     bool operator==(const PolygonRef& other) const =delete;
 
     ClipperLib::Path& operator*() { return *path; }
-    
+
+    const ClipperLib::Path& operator*() const { return *path; }
+
     template <typename... Args>
     void emplace_back(Args&&... args)
     {
@@ -85,7 +95,7 @@ public:
 
     void remove(unsigned int index)
     {
-        POLY_ASSERT(index < size() && index >= 0);
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
         path->erase(path->begin() + index);
     }
 
@@ -188,7 +198,7 @@ public:
         return Point(x, y);
     }
 
-    Point closestPointTo(Point p)
+    Point closestPointTo(Point p) const
     {
         Point ret = p;
         float bestDist = FLT_MAX;
@@ -251,7 +261,7 @@ public:
      * \param remove_length The length of the largest segment removed
      * \param result (output) The result polygon, assumed to be empty
      */
-    void smooth(int remove_length, PolygonRef result);
+    void smooth(int remove_length, PolygonRef result) const;
 
     /*!
      * Smooth out sharp inner corners, by taking a shortcut which bypasses the corner
@@ -269,7 +279,7 @@ public:
      * \param remove_length The length of the largest segment removed
      * \param result (output) The result polygon, assumed to be empty
      */
-    void smooth2(int remove_length, PolygonRef result);
+    void smooth2(int remove_length, PolygonRef result) const;
 
     /*! 
      * Removes consecutive line segments with same orientation and changes this polygon.
@@ -373,6 +383,193 @@ private:
     static void smooth_outward_step(const Point p1, const int64_t shortcut_length2, ListPolyIt& p0_it, ListPolyIt& p2_it, bool& forward_is_blocked, bool& backward_is_blocked, bool& forward_is_too_far, bool& backward_is_too_far);
 };
 
+class ConstPolygonRef
+{
+    const ClipperLib::Path* path;
+    ConstPolygonRef()
+    : path(nullptr)
+    {}
+public:
+    ConstPolygonRef(const ClipperLib::Path& polygon)
+    : path(&polygon)
+    {}
+    ConstPolygonRef(const PolygonRef& polygon)
+    : path(&(*polygon))
+    {}
+
+    unsigned int size() const
+    {
+        return path->size();
+    }
+
+    const Point& operator[] (unsigned int index) const
+    {
+        POLY_ASSERT(index < size());
+        return (*path)[index];
+    }
+
+    const void* data() const
+    {
+        return path->data();
+    }
+
+    ConstPolygonRef& operator=(const ConstPolygonRef& other) { path = other.path; return *this; }
+
+    ConstPolygonRef& operator=(const PolygonRef& other) { path = &(*other); return *this; }
+
+    bool operator==(const ConstPolygonRef& other) const =delete;
+
+    const ClipperLib::Path& operator*() const { return *path; }
+
+    /*!
+     * On Y-axis positive upward displays, Orientation will return true if the polygon's orientation is counter-clockwise.
+     *
+     * from http://www.angusj.com/delphi/clipper/documentation/Docs/Units/ClipperLib/Functions/Orientation.htm
+     */
+    bool orientation() const
+    {
+        return ClipperLib::Orientation(*path);
+    }
+
+    Polygons offset(int distance, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miter_limit = 1.2) const;
+
+    int64_t polygonLength() const
+    {
+        int64_t length = 0;
+        Point p0 = (*path)[path->size()-1];
+        for(unsigned int n=0; n<path->size(); n++)
+        {
+            Point p1 = (*path)[n];
+            length += vSize(p0 - p1);
+            p0 = p1;
+        }
+        return length;
+    }
+
+    bool shorterThan(int64_t check_length) const;
+
+    Point min() const
+    {
+        Point ret = Point(POINT_MAX, POINT_MAX);
+        for(Point p : *path)
+        {
+            ret.X = std::min(ret.X, p.X);
+            ret.Y = std::min(ret.Y, p.Y);
+        }
+        return ret;
+    }
+
+    Point max() const
+    {
+        Point ret = Point(POINT_MIN, POINT_MIN);
+        for(Point p : *path)
+        {
+            ret.X = std::max(ret.X, p.X);
+            ret.Y = std::max(ret.Y, p.Y);
+        }
+        return ret;
+    }
+
+    double area() const
+    {
+        return ClipperLib::Area(*path);
+    }
+
+    Point centerOfMass() const
+    {
+        double x = 0, y = 0;
+        Point p0 = (*path)[path->size()-1];
+        for(unsigned int n=0; n<path->size(); n++)
+        {
+            Point p1 = (*path)[n];
+            double second_factor = (p0.X * p1.Y) - (p1.X * p0.Y);
+
+            x += double(p0.X + p1.X) * second_factor;
+            y += double(p0.Y + p1.Y) * second_factor;
+            p0 = p1;
+        }
+
+        double area = Area(*path);
+
+        x = x / 6 / area;
+        y = y / 6 / area;
+
+        return Point(x, y);
+    }
+
+    Point closestPointTo(Point p) const
+    {
+        Point ret = p;
+        float bestDist = FLT_MAX;
+        for(unsigned int n=0; n<path->size(); n++)
+        {
+            float dist = vSize2f(p - (*path)[n]);
+            if (dist < bestDist)
+            {
+                ret = (*path)[n];
+                bestDist = dist;
+            }
+        }
+        return ret;
+    }
+
+    /*!
+     * Clipper function.
+     * Returns false if outside, true if inside; if the point lies exactly on the border, will return 'border_result'.
+     *
+     * http://www.angusj.com/delphi/clipper/documentation/Docs/Units/ClipperLib/Functions/PointInPolygon.htm
+     */
+    bool inside(Point p, bool border_result = false) const
+    {
+        int res = ClipperLib::PointInPolygon(p, *path);
+        if (res == -1)
+        {
+            return border_result;
+        }
+        return res == 1;
+    }
+
+    /*!
+     * Smooth out small perpendicular segments and store the result in \p result.
+     * Smoothing is performed by removing the inner most vertex of a line segment smaller than \p remove_length
+     * which has an angle with the next and previous line segment smaller than roughly 150*
+     *
+     * Note that in its current implementation this function doesn't remove line segments with an angle smaller than 30*
+     * Such would be the case for an N shape.
+     *
+     * \param remove_length The length of the largest segment removed
+     * \param result (output) The result polygon, assumed to be empty
+     */
+    void smooth(int remove_length, PolygonRef result) const;
+
+    /*!
+     * Smooth out the polygon and store the result in \p result.
+     * Smoothing is performed by removing vertices for which both connected line segments are smaller than \p remove_length
+     *
+     * \param remove_length The length of the largest segment removed
+     * \param result (output) The result polygon, assumed to be empty
+     */
+    void smooth2(int remove_length, PolygonRef result) const;
+
+    ClipperLib::Path::const_reference back() const
+    {
+        return path->back();
+    }
+
+    ClipperLib::Path::const_iterator begin() const
+    {
+        return path->begin();
+    }
+
+    ClipperLib::Path::const_iterator end() const
+    {
+        return path->end();
+    }
+
+    friend class Polygons;
+    friend class Polygon;
+};
+
 class Polygon : public PolygonRef
 {
     ClipperLib::Path poly;
@@ -395,6 +592,7 @@ class Polygons
 {
     friend class Polygon;
     friend class PolygonRef;
+    friend class ConstPolygonRef;
 protected:
     ClipperLib::Paths paths;
 public:
@@ -405,14 +603,14 @@ public:
 
     unsigned int pointCount() const; //!< Return the amount of points in all polygons
 
-    PolygonRef operator[] (unsigned int index)
+    ClipperLib::Path& operator[] (unsigned int index)
     {
-        POLY_ASSERT(index < size() && index >= 0);
-        return PolygonRef(paths[index]);
+        POLY_ASSERT(index < size() && index <= std::numeric_limits<int>::max());
+        return paths[index];
     }
-    const PolygonRef operator[] (unsigned int index) const
+    ConstPolygonRef operator[] (unsigned int index) const
     {
-        return const_cast<Polygons*>(this)->operator[](index);
+        return paths[index];
     }
     ClipperLib::Paths::iterator begin()
     {
@@ -430,11 +628,23 @@ 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() && index >= 0);
-        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);
@@ -447,6 +657,10 @@ public:
     {
         paths.push_back(*poly.path);
     }
+    void add(const ConstPolygonRef& poly)
+    {
+        paths.push_back(*poly.path);
+    }
     void add(Polygon&& other_poly)
     {
         paths.emplace_back(std::move(*other_poly));
@@ -456,6 +670,13 @@ 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)
@@ -463,22 +684,19 @@ public:
         paths.emplace_back(args...);
     }
 
-    PolygonRef newPoly()
+    ClipperLib::Path& newPoly()
     {
         paths.emplace_back();
-        return PolygonRef(paths.back());
+        return paths.back();
     }
-    PolygonRef back()
+    ClipperLib::Path& back()
     {
-        return PolygonRef(paths.back());
+        return paths.back();
     }
 
     Polygons() {}
 
     Polygons(const Polygons& other) { paths = other.paths; }
-
-    virtual ~Polygons() {}
-
     Polygons& operator=(const Polygons& other) { paths = other.paths; return *this; }
 
     bool operator==(const Polygons& other) const =delete;
@@ -517,6 +735,20 @@ 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;
@@ -552,7 +784,7 @@ public:
      * \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)
      */
-    virtual bool inside(Point p, bool border_result = false) const;
+    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,
@@ -615,7 +847,7 @@ public:
      * \param remove_length The length of the largest segment removed
      * \return The smoothed polygon
      */
-    Polygons smooth(int remove_length);
+    Polygons smooth(int remove_length) const;
 
     /*!
      * Smooth out sharp inner corners, by taking a shortcut which bypasses the corner
@@ -626,7 +858,7 @@ public:
      */
     Polygons smooth_outward(float angle, int shortcut_length);
 
-    Polygons smooth2(int remove_length, int min_area); //!< removes points connected to small lines
+    Polygons smooth2(int remove_length, int min_area) const; //!< removes points connected to small lines
     
     /*!
      * removes points connected to similarly oriented lines
@@ -641,7 +873,7 @@ public:
         Polygons& thiss = *this;
         for (unsigned int p = 0; p < size(); p++)
         {
-            thiss[p].simplify(smallest_line_segment_squared, allowed_error_distance_squared);
+            PolygonRef{thiss[p]}.simplify(smallest_line_segment_squared, allowed_error_distance_squared);
             if (thiss[p].size() < 3)
             {
                 remove(p);
@@ -702,7 +934,7 @@ public:
         Polygons& thiss = *this;
         for(unsigned int i=0; i<size(); i++)
         {
-            double area = INT2MM(INT2MM(fabs(thiss[i].area())));
+            double area = INT2MM(INT2MM(fabs(PolygonRef{thiss[i]}.area())));
             if (area < minAreaSize) // Only create an up/down skin if the area is large enough. So you do not create tiny blobs of "trying to fill"
             {
                 remove(i);
@@ -766,16 +998,16 @@ public:
      * Removes the same polygons from this set (and also empty polygons).
      * Polygons are considered the same if all points lie within [same_distance] of their counterparts.
      */
-    Polygons remove(Polygons& to_be_removed, int same_distance = 0)
+    Polygons remove(const Polygons& to_be_removed, int same_distance = 0) const
     {
         Polygons result;
         for (unsigned int poly_keep_idx = 0; poly_keep_idx < size(); poly_keep_idx++)
         {
-            PolygonRef poly_keep = (*this)[poly_keep_idx];
+            ConstPolygonRef poly_keep = (*this)[poly_keep_idx];
             bool should_be_removed = false;
             if (poly_keep.size() > 0) 
 //             for (int hole_poly_idx = 0; hole_poly_idx < to_be_removed.size(); hole_poly_idx++)
-            for (PolygonRef poly_rem : to_be_removed)
+            for (ConstPolygonRef poly_rem : to_be_removed)
             {
 //                 PolygonRef poly_rem = to_be_removed[hole_poly_idx];
                 if (poly_rem.size() != poly_keep.size() || poly_rem.size() == 0) continue;
@@ -891,25 +1123,28 @@ public:
 class PolygonsPart : public Polygons
 {   
 public:
-    PolygonRef outerPolygon() 
+    PolygonRef outerPolygon()
     {
-        Polygons& thiss = *this;
-        return thiss[0];
+        return this->paths[0];
+    }
+    ConstPolygonRef outerPolygon() const
+    {
+        return this->paths[0];
+    }
+    
+    bool inside(Point p)
+    {
+        if (size() < 1)
+            return false;
+        if (!PolygonRef{(*this)[0]}.inside(p))
+            return false;
+        for(unsigned int n=1; n<paths.size(); n++)
+        {
+            if (PolygonRef{(*this)[n]}.inside(p))
+                return false;
+        }
+        return true;
     }
-
-    /*!
-     * 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)
-     */
-    virtual bool inside(Point p, bool border_result = false) const;
 };
 
 /*!

src/utils/polygonUtils.cpp

@@ -22,7 +22,7 @@ int64_t PolygonUtils::segmentLength(PolygonsPointIndex start, PolygonsPointIndex
     assert(start.poly_idx == end.poly_idx);
     int64_t segment_length = 0;
     Point prev_vert = start.p();
-    const PolygonRef poly = (*start.polygons)[start.poly_idx];
+    ConstPolygonRef poly = (*start.polygons)[start.poly_idx];
     for (unsigned int point_idx = 1; point_idx <= poly.size(); point_idx++)
     {
         unsigned int vert_idx = (start.point_idx + point_idx) % poly.size();
@@ -44,7 +44,7 @@ void PolygonUtils::spreadDots(PolygonsPointIndex start, PolygonsPointIndex end,
     assert(start.poly_idx == end.poly_idx);
     int64_t segment_length = segmentLength(start, end);
 
-    const PolygonRef poly = (*start.polygons)[start.poly_idx];
+    ConstPolygonRef poly = (*start.polygons)[start.poly_idx];
     unsigned int n_dots_in_between = n_dots;
     if (start == end)
     {
@@ -80,7 +80,7 @@ void PolygonUtils::spreadDots(PolygonsPointIndex start, PolygonsPointIndex end,
     assert(result.size() == n_dots && "we didn't generate as many wipe locations as we asked for.");
 }
 
-Point PolygonUtils::getVertexInwardNormal(PolygonRef poly, unsigned int point_idx)
+Point PolygonUtils::getVertexInwardNormal(ConstPolygonRef poly, unsigned int point_idx)
 {
     Point p1 = poly[point_idx];
 
@@ -110,7 +110,7 @@ Point PolygonUtils::getVertexInwardNormal(PolygonRef poly, unsigned int point_id
             break;
         }
     }
-    Point& p2 = poly[p2_idx];
+    const Point& p2 = poly[p2_idx];
 
     Point off0 = turn90CCW(normal(p1 - p0, MM2INT(10.0))); // 10.0 for some precision
     Point off1 = turn90CCW(normal(p2 - p1, MM2INT(10.0))); // 10.0 for some precision
@@ -119,7 +119,7 @@ Point PolygonUtils::getVertexInwardNormal(PolygonRef poly, unsigned int point_id
 }
 
 
-Point PolygonUtils::getBoundaryPointWithOffset(PolygonRef poly, unsigned int point_idx, int64_t offset)
+Point PolygonUtils::getBoundaryPointWithOffset(ConstPolygonRef poly, unsigned int point_idx, int64_t offset)
 {
     return poly[point_idx] + normal(getVertexInwardNormal(poly, point_idx), -offset);
 }
@@ -130,7 +130,7 @@ Point PolygonUtils::moveInsideDiagonally(ClosestPolygonPoint point_on_boundary,
     {
         return no_point;
     }
-    PolygonRef poly = *point_on_boundary.poly;
+    ConstPolygonRef 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))
@@ -163,7 +163,7 @@ ClosestPolygonPoint PolygonUtils::moveInside2(const Polygons& polygons, Point& f
     return _moveInside2(*closest_polygon_point, distance, from, max_dist2);
 }
 
-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)
+ClosestPolygonPoint PolygonUtils::moveInside2(const Polygons& loc_to_line_polygons, ConstPolygonRef polygon, Point& from, const int distance, const int64_t max_dist2, const LocToLineGrid* loc_to_line_grid, const std::function<int(Point)>& penalty_function)
 {
     std::optional<ClosestPolygonPoint> closest_polygon_point;
     if (loc_to_line_grid)
@@ -225,7 +225,7 @@ unsigned int PolygonUtils::moveInside(const Polygons& polygons, Point& from, int
     bool is_already_on_correct_side_of_boundary = false; // whether [from] is already on the right side of the boundary
     for (unsigned int poly_idx = 0; poly_idx < polygons.size(); poly_idx++)
     {
-        const PolygonRef poly = polygons[poly_idx];
+        ConstPolygonRef poly = polygons[poly_idx];
         if (poly.size() < 2)
             continue;
         Point p0 = poly[poly.size()-2];
@@ -344,11 +344,11 @@ Point PolygonUtils::moveInside(const ClosestPolygonPoint& cpp, const int distanc
     { // the point which is assumed to be on the boundary doesn't have to be moved
         return cpp.location;
     }
-    const PolygonRef poly = *cpp.poly;
+    ConstPolygonRef poly = *cpp.poly;
     unsigned int point_idx = cpp.point_idx;
     const Point& on_boundary = cpp.location;
 
-    Point& p1 = poly[point_idx];
+    const Point& p1 = poly[point_idx];
     unsigned int p2_idx;
     for (p2_idx = point_idx + 1; p2_idx != point_idx; p2_idx = p2_idx + 1)
     { // find the next point different from p1
@@ -361,7 +361,7 @@ Point PolygonUtils::moveInside(const ClosestPolygonPoint& cpp, const int distanc
             break;
         }
     }
-    Point& p2 = poly[p2_idx];
+    const Point& p2 = poly[p2_idx];
 
     if (on_boundary == p1)
     {
@@ -392,7 +392,7 @@ ClosestPolygonPoint PolygonUtils::ensureInsideOrOutside(const Polygons& polygons
     {
         return ClosestPolygonPoint(); // we couldn't move inside
     }
-    PolygonRef closest_poly = *closest_polygon_point.poly;
+    ConstPolygonRef closest_poly = *closest_polygon_point.poly;
     bool is_outside_boundary = closest_poly.orientation();
 
     {
@@ -481,8 +481,8 @@ void PolygonUtils::findSmallestConnection(ClosestPolygonPoint& poly1_result, Clo
     {
         return;
     }
-    PolygonRef poly1 = *poly1_result.poly;
-    PolygonRef poly2 = *poly2_result.poly;
+    ConstPolygonRef poly1 = *poly1_result.poly;
+    ConstPolygonRef poly2 = *poly2_result.poly;
     if (poly1.size() == 0 || poly2.size() == 0)
     {
         return;
@@ -515,8 +515,8 @@ void PolygonUtils::walkToNearestSmallestConnection(ClosestPolygonPoint& poly1_re
     {
         return;
     }
-    PolygonRef poly1 = *poly1_result.poly;
-    PolygonRef poly2 = *poly2_result.poly;
+    ConstPolygonRef poly1 = *poly1_result.poly;
+    ConstPolygonRef poly2 = *poly2_result.poly;
     if (poly1_result.point_idx < 0 || poly2_result.point_idx < 0)
     {
         return;
@@ -537,7 +537,7 @@ void PolygonUtils::walkToNearestSmallestConnection(ClosestPolygonPoint& poly1_re
     }
 }
 
-ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, PolygonRef polygon, int start_idx)
+ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, ConstPolygonRef polygon, int start_idx)
 {
     ClosestPolygonPoint forth = findNearestClosest(from, polygon, start_idx, 1);
     if (!forth.isValid())
@@ -556,7 +556,7 @@ ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, PolygonRef poly
     }
 }
 
-ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, PolygonRef polygon, int start_idx, int direction)
+ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, ConstPolygonRef polygon, int start_idx, int direction)
 {
     if (polygon.size() == 0)
     {
@@ -572,8 +572,8 @@ ClosestPolygonPoint PolygonUtils::findNearestClosest(Point from, PolygonRef poly
     {
         int p1_idx = (polygon.size() + direction*p + start_idx) % polygon.size();
         int p2_idx = (polygon.size() + direction*(p+1) + start_idx) % polygon.size();
-        Point& p1 = polygon[p1_idx];
-        Point& p2 = polygon[p2_idx];
+        const Point& p1 = polygon[p1_idx];
+        const Point& p2 = polygon[p2_idx];
 
         Point closest_here = LinearAlg2D::getClosestOnLineSegment(from, p1 ,p2);
         int64_t dist = vSize2(from - closest_here);
@@ -596,18 +596,31 @@ ClosestPolygonPoint PolygonUtils::findClosest(Point from, const Polygons& polygo
 {
     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;
+    }
+    ConstPolygonRef 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);
     
     for (unsigned int ply = 0; ply < polygons.size(); ply++)
     {
-        const PolygonRef poly = polygons[ply];
+        ConstPolygonRef poly = polygons[ply];
         if (poly.size() == 0) continue;
         ClosestPolygonPoint closest_here = findClosest(from, poly, penalty_function);
         if (!closest_here.isValid())
@@ -626,7 +639,7 @@ ClosestPolygonPoint PolygonUtils::findClosest(Point from, const Polygons& polygo
     return best;
 }
 
-ClosestPolygonPoint PolygonUtils::findClosest(Point from, const PolygonRef polygon, const std::function<int(Point)>& penalty_function)
+ClosestPolygonPoint PolygonUtils::findClosest(Point from, ConstPolygonRef polygon, const std::function<int(Point)>& penalty_function)
 {
     if (polygon.size() == 0)
     {
@@ -640,11 +653,11 @@ ClosestPolygonPoint PolygonUtils::findClosest(Point from, const PolygonRef polyg
 //
     for (unsigned int p = 0; p<polygon.size(); p++)
     {
-        Point& p1 = polygon[p];
+        const Point& p1 = polygon[p];
 
         unsigned int p2_idx = p+1;
         if (p2_idx >= polygon.size()) p2_idx = 0;
-        Point& p2 = polygon[p2_idx];
+        const Point& p2 = polygon[p2_idx];
 
         Point closest_here = LinearAlg2D::getClosestOnLineSegment(from, p1 ,p2);
         int64_t dist2_score = vSize2(from - closest_here) + penalty_function(closest_here);
@@ -665,7 +678,7 @@ PolygonsPointIndex PolygonUtils::findNearestVert(const Point from, const Polygon
     PolygonsPointIndex closest_vert;
     for (unsigned int poly_idx = 0; poly_idx < polys.size(); poly_idx++)
     {
-        const PolygonRef poly = polys[poly_idx];
+        ConstPolygonRef poly = polys[poly_idx];
         for (unsigned int point_idx = 0; point_idx < poly.size(); point_idx++)
         {
             int64_t dist2 = vSize2(poly[point_idx] - from);
@@ -708,7 +721,7 @@ LocToLineGrid* PolygonUtils::createLocToLineGrid(const Polygons& polygons, int s
 
     for (unsigned int poly_idx = 0; poly_idx < polygons.size(); poly_idx++)
     {
-        const PolygonRef poly = polygons[poly_idx];
+        ConstPolygonRef poly = polygons[poly_idx];
         for (unsigned int point_idx = 0; point_idx < poly.size(); point_idx++)
         {
             ret->insert(PolygonsPointIndex(&polygons, poly_idx, point_idx));
@@ -739,9 +752,9 @@ std::optional<ClosestPolygonPoint> PolygonUtils::findClose(
     PolygonsPointIndex best_point_poly_idx(nullptr, NO_INDEX, NO_INDEX);
     for (PolygonsPointIndex& point_poly_index : near_lines)
     {
-        const PolygonRef poly = polygons[point_poly_index.poly_idx];
-        Point& p1 = poly[point_poly_index.point_idx];
-        Point& p2 = poly[(point_poly_index.point_idx + 1) % poly.size()];
+        ConstPolygonRef poly = polygons[point_poly_index.poly_idx];
+        const Point& p1 = poly[point_poly_index.point_idx];
+        const Point& p2 = poly[(point_poly_index.point_idx + 1) % poly.size()];
 
         Point closest_here = LinearAlg2D::getClosestOnLineSegment(from, p1 ,p2);
         int64_t dist2_score = vSize2(from - closest_here) + penalty_function(closest_here);
@@ -765,7 +778,7 @@ std::optional<ClosestPolygonPoint> PolygonUtils::findClose(
 
 
 std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> PolygonUtils::findClose(
-    const PolygonRef from, const Polygons& destination,
+    ConstPolygonRef from, const Polygons& destination,
     const LocToLineGrid& destination_loc_to_line,
     const std::function<int(Point)>& penalty_function)
 {
@@ -804,7 +817,7 @@ std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> PolygonUtils::f
 
 
 
-bool PolygonUtils::getNextPointWithDistance(Point from, int64_t dist, const PolygonRef poly, int start_idx, int poly_start_idx, GivenDistPoint& result)
+bool PolygonUtils::getNextPointWithDistance(Point from, int64_t dist, ConstPolygonRef poly, int start_idx, int poly_start_idx, GivenDistPoint& result)
 {
     
     Point prev_poly_point = poly[(start_idx + poly_start_idx) % poly.size()];
@@ -812,7 +825,7 @@ bool PolygonUtils::getNextPointWithDistance(Point from, int64_t dist, const Poly
     for (unsigned int prev_idx = start_idx; prev_idx < poly.size(); prev_idx++) 
     {
         int next_idx = (prev_idx + 1 + poly_start_idx) % poly.size(); // last checked segment is between last point in poly and poly[0]...
-        Point& next_poly_point = poly[next_idx];
+        const Point& next_poly_point = poly[next_idx];
         if ( !shorterThen(next_poly_point - from, dist) )
         {
             /*
@@ -919,7 +932,7 @@ bool PolygonUtils::polygonCollidesWithLineSegment(const Point from, const Point
     return ret;
 }
 
-bool PolygonUtils::polygonCollidesWithLineSegment(const PolygonRef poly, Point& transformed_startPoint, Point& transformed_endPoint, PointMatrix transformation_matrix)
+bool PolygonUtils::polygonCollidesWithLineSegment(ConstPolygonRef poly, const Point& transformed_startPoint, const Point& transformed_endPoint, PointMatrix transformation_matrix)
 {
     Point p0 = transformation_matrix.apply(poly.back());
     for(Point p1_ : poly)
@@ -934,7 +947,7 @@ bool PolygonUtils::polygonCollidesWithLineSegment(const PolygonRef poly, Point&
     return false;
 }
 
-bool PolygonUtils::polygonCollidesWithLineSegment(const PolygonRef poly, Point& startPoint, Point& endPoint)
+bool PolygonUtils::polygonCollidesWithLineSegment(PolygonRef poly, const Point& startPoint, const Point& endPoint)
 {
     Point diff = endPoint - startPoint;
 
@@ -945,9 +958,9 @@ bool PolygonUtils::polygonCollidesWithLineSegment(const PolygonRef poly, Point&
     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, const Point& transformed_startPoint, const Point& transformed_endPoint, PointMatrix transformation_matrix)
 {
-    for (const PolygonRef poly : const_cast<Polygons&>(polys))
+    for (ConstPolygonRef poly : polys)
     {
         if (poly.size() == 0) { continue; }
         if (PolygonUtils::polygonCollidesWithLineSegment(poly, transformed_startPoint, transformed_endPoint, transformation_matrix))
@@ -960,7 +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, const Point& startPoint, const Point& endPoint)
 {
     Point diff = endPoint - startPoint;
 

src/utils/polygonUtils.h

@@ -20,12 +20,12 @@ namespace cura
 struct ClosestPolygonPoint
 {
     Point location; //!< Result location
-    std::optional<PolygonRef> poly; //!< Polygon in which the result was found (or none if no result was found)
+    std::optional<ConstPolygonRef> 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(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(Point p, int pos, ConstPolygonRef poly) :  location(p), poly(true, poly), poly_idx(NO_INDEX), point_idx(pos) {};
+    ClosestPolygonPoint(Point p, int pos, ConstPolygonRef poly, int poly_idx) :  location(p), poly(true, poly), poly_idx(poly_idx), point_idx(pos) {};
+    ClosestPolygonPoint(ConstPolygonRef 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
@@ -53,7 +53,7 @@ struct PolygonsPointIndexSegmentLocator
 {
     std::pair<Point, Point> operator()(const PolygonsPointIndex& val) const
     {
-        PolygonRef poly = (*val.polygons)[val.poly_idx];
+        ConstPolygonRef poly = (*val.polygons)[val.poly_idx];
         Point start = poly[val.point_idx];
         unsigned int next_point_idx = (val.point_idx + 1) % poly.size();
         Point end = poly[next_point_idx];
@@ -104,7 +104,7 @@ public:
      * \param poly The polygon.
      * \param point_idx The index of the point in the polygon.
      */
-    static Point getVertexInwardNormal(PolygonRef poly, unsigned int point_idx);
+    static Point getVertexInwardNormal(ConstPolygonRef poly, unsigned int point_idx);
 
     /*!
     * Get a point from the \p poly with a given \p offset.
@@ -114,7 +114,7 @@ public:
     * \param offset The distance the point has to be moved outward from the polygon.
     * \return A point at the given distance inward from the point on the boundary polygon.
     */
-    static Point getBoundaryPointWithOffset(PolygonRef poly, unsigned int point_idx, int64_t offset);
+    static Point getBoundaryPointWithOffset(ConstPolygonRef poly, unsigned int point_idx, int64_t offset);
 
     /*!
      * Move a point away from the boundary by looking at the boundary normal of the nearest vert.
@@ -178,7 +178,7 @@ public:
      * \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& 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);
+    static ClosestPolygonPoint moveInside2(const Polygons& loc_to_line_polygons, ConstPolygonRef 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.
@@ -298,7 +298,7 @@ public:
     * \param start_idx The index of the point in the polygon from which to start looking.
     * \return The nearest point from \p start_idx going along the \p polygon (in both directions) with a locally minimal distance to \p from.
     */
-    static ClosestPolygonPoint findNearestClosest(Point from, const PolygonRef polygon, int start_idx);
+    static ClosestPolygonPoint findNearestClosest(Point from, ConstPolygonRef polygon, int start_idx);
 
     /*!
     * Find the nearest closest point on a polygon from a given index walking in one direction along the polygon.
@@ -309,7 +309,7 @@ public:
     * \param direction The direction to walk: 1 for walking along the \p polygon, -1 for walking in opposite direction
     * \return The nearest point from \p start_idx going along the \p polygon with a locally minimal distance to \p from.
     */
-    static ClosestPolygonPoint findNearestClosest(const Point from, const PolygonRef polygon, int start_idx, int direction);
+    static ClosestPolygonPoint findNearestClosest(const Point from, ConstPolygonRef polygon, int start_idx, int direction);
 
     /*!
      * Find the point closest to \p from in all polygons in \p polygons.
@@ -327,7 +327,7 @@ public:
      * 
      * \param penalty_function A function returning a penalty term on the squared distance score of a candidate point.
      */
-    static ClosestPolygonPoint findClosest(Point from, const PolygonRef polygon, const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static ClosestPolygonPoint findClosest(Point from, ConstPolygonRef polygon, const std::function<int(Point)>& penalty_function = no_penalty_function);
 
     /*!
      * Find the nearest vertex to \p from in \p polys
@@ -382,7 +382,7 @@ 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 LocToLineGrid& destination_loc_to_line, const std::function<int(Point)>& penalty_function = no_penalty_function);
+    static std::vector<std::pair<ClosestPolygonPoint, ClosestPolygonPoint>> findClose(ConstPolygonRef 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.
@@ -409,7 +409,7 @@ public:
     * \param start_idx the index of the prev poly point on the poly.
     * \param poly_start_idx The index of the point in the polygon which is to be handled as the start of the polygon. No point further than this point will be the result.
     */
-    static bool getNextPointWithDistance(Point from, int64_t dist, const PolygonRef poly, int start_idx, int poly_start_idx, GivenDistPoint& result);
+    static bool getNextPointWithDistance(Point from, int64_t dist, ConstPolygonRef poly, int start_idx, int poly_start_idx, GivenDistPoint& result);
 
 
 
@@ -433,7 +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(ConstPolygonRef poly, const Point& transformed_startPoint, const Point& transformed_endPoint, PointMatrix transformation_matrix);
 
     /*!
      * Checks whether a given line segment collides with a given polygon(s).
@@ -449,7 +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, const Point& startPoint, const Point& endPoint);
 
     /*!
      * Checks whether a given line segment collides with a given polygon(s).
@@ -471,7 +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, const Point& transformed_startPoint, const Point& transformed_endPoint, PointMatrix transformation_matrix);
 
     /*!
      * Checks whether a given line segment collides with a given polygon(s).
@@ -487,7 +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, const Point& startPoint, const Point& endPoint);
 
 private:
     /*!

src/wallOverlap.cpp

@@ -18,7 +18,7 @@ WallOverlapComputation::WallOverlapComputation(Polygons& polygons, int line_widt
 }
 
 
-float WallOverlapComputation::getFlow(Point& from, Point& to)
+float WallOverlapComputation::getFlow(const Point& from, const Point& to)
 {
     using Point2LinkIt = PolygonProximityLinker::Point2Link::iterator;
 

src/wallOverlap.h

@@ -60,7 +60,7 @@ public:
      * \param to The ending of the line segment
      * \return a value between zero and one representing the reduced flow of the line segment
      */
-    float getFlow(Point& from, Point& to);
+    float getFlow(const Point& from, const Point& to);
 
     /*!
      * Computes the neccesary priliminaries in order to efficiently compute the flow when generatign gcode paths.

tests/GCodePlannerTest.cpp

@@ -36,9 +36,9 @@ void GCodePlannerTest::setUp()
     fan_speed_layer_time_settings.cool_min_speed = 0.5;
     std::vector<FanSpeedLayerTimeSettings> fan_speed_layer_time_settings_per_extruder;
     fan_speed_layer_time_settings_per_extruder.push_back(fan_speed_layer_time_settings);
-    //                              Slice     layer  z  layer   last        current   fan speed and layer                        combing           comb    travel  travel avoid
-    //                              storage   nr        height  position    extruder  time settings                              mode              offset  avoid   distance
-    gCodePlanner = new GCodePlanner(*storage, 0,     0, 0.1,    Point(0,0), 0,        fan_speed_layer_time_settings_per_extruder, CombingMode::OFF, 100,    false,  50          );
+    //                              Slice     layer  z  layer   last        current   is inside  fan speed and layer                        combing           comb    travel  travel avoid
+    //                              storage   nr        height  position    extruder  mesh       time settings                              mode              offset  avoid   distance
+    gCodePlanner = new GCodePlanner(*storage, 0,     0, 0.1,    Point(0,0), 0,        false,     fan_speed_layer_time_settings_per_extruder, CombingMode::OFF, 100,    false,  50          );
 }
 
 void GCodePlannerTest::tearDown()