Only include OpenMP headers if we are actually compiling with OpenMP

Fixes building on OSX with Clang

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)

src/FffGcodeWriter.cpp

@@ -194,7 +194,17 @@ 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"));
-    
+
+        // 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
+        const int perimeter_gaps_line_width = mesh.getSettingInMicrons("wall_line_width_x") / 2;
+        double perimeter_gaps_speed = mesh.getSettingInMillimetersPerSecond("speed_topbottom");
+        if (mesh.getSettingBoolean("speed_equalize_flow_enabled"))
+        {
+            perimeter_gaps_speed = perimeter_gaps_speed * mesh.getSettingInMicrons("skin_line_width") / perimeter_gaps_line_width;
+        }
+        mesh.perimeter_gap_config.init(perimeter_gaps_speed, mesh.getSettingInMillimetersPerSecond("acceleration_topbottom"), mesh.getSettingInMillimetersPerSecond("jerk_topbottom"), perimeter_gaps_line_width, mesh.getSettingInPercentage("material_flow"));
+
         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"));
@@ -864,7 +874,9 @@ void FffGcodeWriter::addMeshPartToGCode(SliceDataStorage& storage, SliceMeshStor
         processSingleLayerInfill(gcode_layer, mesh, part, layer_nr, infill_line_distance, infill_overlap, infill_angle);
     }
 
-    EFillMethod skin_pattern = mesh->getSettingAsFillMethod("top_bottom_pattern");
+    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)
     {
@@ -997,7 +1009,7 @@ void FffGcodeWriter::processInsets(GCodePlanner& gcode_layer, SliceMeshStorage*
             { // 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
                 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);
+                gcode_layer.addPolygonsByOptimizer(part.insets[0], &mesh->insetX_config, wall_overlap_computation, EZSeamType::SHORTEST, z_seam_pos, wall_0_wipe_dist, spiralize);
             }
         }
         int processed_inset_number = -1;
@@ -1044,9 +1056,11 @@ void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, Slic
 {
     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");
 
     Point z_seam_pos(0, 0); // not used
     PathOrderOptimizer part_order_optimizer(gcode_layer.getLastPosition(), z_seam_pos, EZSeamType::SHORTEST);
@@ -1064,7 +1078,9 @@ void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, Slic
         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]);
@@ -1116,13 +1132,6 @@ void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, Slic
         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)
@@ -1133,6 +1142,16 @@ void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, Slic
         {
             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)
@@ -1148,7 +1167,10 @@ void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, Slic
             perimeter_gaps.add(outer.difference(inner));
         }
         { // gap between inner wall and skin/infill
-            if (mesh->getSettingInMicrons("infill_line_distance") > 0 && !mesh->getSettingBoolean("infill_hollow"))
+            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);
 
@@ -1157,18 +1179,19 @@ void FffGcodeWriter::processSkinAndPerimeterGaps(GCodePlanner& gcode_layer, Slic
                 {
                     inner.add(skin_part.outline);
                 }
+                inner = inner.unionPolygons();
                 perimeter_gaps.add(outer.difference(inner));
             }
         }
 
-        Polygons skin_polygons; // unused
-        Polygons skin_lines; // soon to be generated gap filler lines
+        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);
     }
 }
 

src/FffPolygonGenerator.cpp

@@ -3,6 +3,10 @@
 #include <algorithm>
 #include <map> // multimap (ordered map allowing duplicate keys)
 
+#ifdef _OPENMP
+    #include <omp.h>"
+#endif
+
 #include "utils/math.h"
 #include "utils/algorithm.h"
 #include "slicer.h"
@@ -151,6 +155,10 @@ 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 +169,10 @@ 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;
         }
@@ -337,12 +349,24 @@ void FffPolygonGenerator::processBasicWallsSkinInfill(SliceDataStorage& storage,
     
     
     // walls
+    unsigned 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);
@@ -373,16 +397,33 @@ 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);
-    }
 }
 
 void FffPolygonGenerator::processInfillMesh(SliceDataStorage& storage, unsigned int mesh_order_idx, std::vector<unsigned int>& mesh_order)
@@ -478,6 +519,12 @@ 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.
+ *
+ * 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];
@@ -516,11 +563,19 @@ 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) 
@@ -551,8 +606,18 @@ 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/SkirtBrim.cpp

@@ -58,6 +58,10 @@ void SkirtBrim::getFirstLayerOutline(SliceDataStorage& storage, const unsigned i
     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)

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/commandSocket.cpp

@@ -642,6 +642,7 @@ void CommandSocket::sendLayerData()
     {
         for (std::pair<const int, std::shared_ptr<cura::proto::Layer>> entry : data.slice_data) //Note: This is in no particular order!
         {
+            logDebug("Sending layer data for layer %i of %i.\n", entry.first, data.slice_data.size());
             private_data->socket->sendMessage(entry.second); //Send the actual layers.
         }
         data.sliced_objects = 0;
@@ -667,6 +668,7 @@ void CommandSocket::sendOptimizedLayerData()
     {
         for (std::pair<const int, std::shared_ptr<cura::proto::LayerOptimized>> entry : data.slice_data) //Note: This is in no particular order!
         {
+            logDebug("Sending layer data for layer %i of %i.\n", entry.first, data.slice_data.size());
             private_data->socket->sendMessage(entry.second); //Send the actual layers.
         }
         data.sliced_objects = 0;

src/gcodeExport.cpp

@@ -556,8 +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!");
 
@@ -570,6 +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)
     {
@@ -729,7 +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);
     }
 }
 
@@ -923,7 +922,7 @@ void GCodeExport::finalize(const char* endCode)
 {
     writeFanCommand(0);
     writeCode(endCode);
-    long print_time = getTotalPrintTime();
+    int64_t print_time = getTotalPrintTime();
     int mat_0 = getTotalFilamentUsed(0);
     log("Print time: %d\n", print_time);
     log("Print time (readable): %dh %dm %ds\n", print_time / 60 / 60, (print_time / 60) % 60, print_time % 60);

src/gcodePlanner.cpp

@@ -897,6 +897,7 @@ 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);
@@ -955,6 +956,7 @@ 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++)
             {
@@ -976,6 +978,7 @@ 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();

src/infill/SubDivCube.cpp

@@ -186,15 +186,15 @@ SubDivCube::SubDivCube(SliceMeshStorage& mesh, Point3& center, unsigned int dept
 bool SubDivCube::isValidSubdivision(SliceMeshStorage& mesh, Point3& center, int64_t radius)
 {
     int64_t distance2;
-    long int sphere_slice_radius2;//!< squared radius of bounding sphere slice on target layer
+    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 long int layer_height = mesh.getSettingInMicrons("layer_height");
-    long int bottom_layer = (center.z - radius) / layer_height;
-    long int top_layer = (center.z + radius) / layer_height;
-    for (long int test_layer = bottom_layer; test_layer <= top_layer; test_layer += 3) // steps of three. Low-hanging speed gain.
+    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));
@@ -221,9 +221,9 @@ bool SubDivCube::isValidSubdivision(SliceMeshStorage& mesh, Point3& center, int6
     return false;
 }
 
-int SubDivCube::distanceFromPointToMesh(SliceMeshStorage& mesh, long int layer_nr, Point& location, int64_t* distance2)
+int SubDivCube::distanceFromPointToMesh(SliceMeshStorage& mesh, int layer_nr, Point& location, int64_t* distance2)
 {
-    if (layer_nr < 0 || (unsigned long int)layer_nr >= mesh.layers.size()) //!< this layer is outside of valid range
+    if (layer_nr < 0 || (unsigned int)layer_nr >= mesh.layers.size()) //!< this layer is outside of valid range
     {
         return 2;
     }

src/infill/SubDivCube.h

@@ -74,7 +74,7 @@ private:
      * \param[out] distance2 the squared distance to the infill border
      * \return Code 0: outside, 1: inside, 2: boundary does not exist at specified layer
      */
-    static int distanceFromPointToMesh(SliceMeshStorage& mesh, long int layer_nr, Point& location, int64_t* distance2);
+    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.

src/layerPart.cpp

@@ -44,7 +44,10 @@ 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();
+    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++)
     {
         mesh.layers[layer_nr].sliceZ = slicer->layers[layer_nr].z;
         mesh.layers[layer_nr].printZ = slicer->layers[layer_nr].z;

src/main.cpp

@@ -20,6 +20,10 @@
 
 #include "settings/SettingsToGV.h"
 
+#ifdef _OPENMP
+    #include <omp.h> // omp_get_num_threads
+#endif
+
 namespace cura
 {
     
@@ -328,7 +332,19 @@ int main(int argc, char **argv)
         print_usage();
         exit(1);
     }
-    
+
+#pragma omp parallel
+    {
+#pragma omp master
+        {
+#ifdef _OPENMP
+            log("OpenMP multithreading enabled, likely number of threads to be used: %u\n", omp_get_num_threads());
+#else
+            log("OpenMP multithreading disabled\n");
+#endif
+        }
+    }
+
     if (stringcasecompare(argv[1], "connect") == 0)
     {
         connect(argc, argv);
@@ -423,4 +439,4 @@ int main(int argc, char **argv)
     }
     
     return 0;
-}
+}

src/settings/SettingRegistry.cpp

@@ -125,7 +125,7 @@ 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()) //... Tough luck, buddy.
+    if (extruder_train_ids.empty())
     {
         logError("Couldn't find any extruder trains!\n");
         return -1;

src/settings/settings.cpp

@@ -93,21 +93,23 @@ void SettingsBase::setSettingInheritBase(std::string key, const SettingsBaseVirt
 
 std::string SettingsBase::getSettingString(std::string key) const
 {
-    if (setting_values.find(key) != setting_values.end())
+    auto value_it = setting_values.find(key);
+    if (value_it != setting_values.end())
     {
-        return setting_values.at(key);
+        return value_it->second;
     }
-    if (setting_inherit_base.find(key) != setting_inherit_base.end())
+    auto inherit_override_it = setting_inherit_base.find(key);
+    if (inherit_override_it != setting_inherit_base.end())
     {
-        return setting_inherit_base.at(key)->getSettingString(key);
+        return inherit_override_it->second->getSettingString(key);
     }
     if (parent)
     {
         return parent->getSettingString(key);
     }
 
-    const_cast<SettingsBase&>(*this).setting_values[key] = "";
-    cura::logWarning("Unregistered setting %s\n", key.c_str());
+    cura::logError("Trying to retrieve unregistered setting with no value given: '%s'\n", key.c_str());
+    std::exit(-1);
     return "";
 }
 
@@ -426,7 +428,7 @@ FillPerimeterGapMode SettingsBaseVirtual::getSettingAsFillPerimeterGapMode(std::
     return FillPerimeterGapMode::NOWHERE;
 }
 
-CombingMode SettingsBaseVirtual::getSettingAsCombingMode(std::string key)
+CombingMode SettingsBaseVirtual::getSettingAsCombingMode(std::string key) const
 {
     std::string value = getSettingString(key);
     if (value == "off")
@@ -444,7 +446,7 @@ CombingMode SettingsBaseVirtual::getSettingAsCombingMode(std::string key)
     return CombingMode::ALL;
 }
 
-SupportDistPriority SettingsBaseVirtual::getSettingAsSupportDistPriority(std::string key)
+SupportDistPriority SettingsBaseVirtual::getSettingAsSupportDistPriority(std::string key) const
 {
     std::string value = getSettingString(key);
     if (value == "xy_overrides_z")

src/settings/settings.h

@@ -251,8 +251,8 @@ public:
     EZSeamType getSettingAsZSeamType(std::string key) const;
     ESurfaceMode getSettingAsSurfaceMode(std::string key) const;
     FillPerimeterGapMode getSettingAsFillPerimeterGapMode(std::string key) const;
-    CombingMode getSettingAsCombingMode(std::string key);
-    SupportDistPriority getSettingAsSupportDistPriority(std::string key);
+    CombingMode getSettingAsCombingMode(std::string key) const;
+    SupportDistPriority getSettingAsSupportDistPriority(std::string key) const;
 };
 
 class SettingRegistry;

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];
@@ -31,7 +46,7 @@ void generateSkinAreas(int layer_nr, SliceMeshStorage& mesh, const int innermost
     {
         return;
     }
-    
+    int min_infill_area = mesh.getSettingInMillimeters("min_infill_area");
     for(unsigned int partNr = 0; partNr < layer.parts.size(); partNr++)
     {
         SliceLayerPart& part = layer.parts[partNr];
@@ -63,12 +78,22 @@ void generateSkinAreas(int layer_nr, SliceMeshStorage& mesh, const int innermost
         {
             if (static_cast<int>(layer_nr - downSkinCount) >= 0)
             {
-                downskin = downskin.difference(getInsidePolygons(mesh.layers[layer_nr - downSkinCount])); // skin overlaps with the walls
+                Polygons not_air = getInsidePolygons(mesh.layers[layer_nr - downSkinCount]);
+                if (min_infill_area > 0)
+                {
+                    not_air.removeSmallAreas(min_infill_area);
+                }
+                downskin = downskin.difference(not_air); // skin overlaps with the walls
             }
             
             if (static_cast<int>(layer_nr + upSkinCount) < static_cast<int>(mesh.layers.size()))
             {
-                upskin = upskin.difference(getInsidePolygons(mesh.layers[layer_nr + upSkinCount])); // skin overlaps with the walls
+                Polygons not_air = getInsidePolygons(mesh.layers[layer_nr + upSkinCount]);
+                if (min_infill_area > 0)
+                {
+                    not_air.removeSmallAreas(min_infill_area);
+                }
+                upskin = upskin.difference(not_air); // skin overlaps with the walls
             }
         }
         else 
@@ -80,6 +105,10 @@ void generateSkinAreas(int layer_nr, SliceMeshStorage& mesh, const int innermost
                 {
                     not_air = not_air.intersection(getInsidePolygons(mesh.layers[downskin_layer_nr]));
                 }
+                if (min_infill_area > 0)
+                {
+                    not_air.removeSmallAreas(min_infill_area);
+                }
                 downskin = downskin.difference(not_air); // skin overlaps with the walls
             }
             
@@ -90,6 +119,10 @@ void generateSkinAreas(int layer_nr, SliceMeshStorage& mesh, const int innermost
                 {
                     not_air = not_air.intersection(getInsidePolygons(mesh.layers[upskin_layer_nr]));
                 }
+                if (min_infill_area > 0)
+                {
+                    not_air.removeSmallAreas(min_infill_area);
+                }
                 upskin = upskin.difference(not_air); // skin overlaps with the walls
             }
         }
@@ -106,7 +139,12 @@ 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 +177,12 @@ 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];

src/sliceDataStorage.cpp

@@ -207,7 +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));
                 }

src/sliceDataStorage.h

@@ -155,6 +155,7 @@ public:
     GCodePathConfig inset0_config;
     GCodePathConfig insetX_config;
     GCodePathConfig skin_config;
+    GCodePathConfig perimeter_gap_config;
     std::vector<GCodePathConfig> infill_config;
 
     SubDivCube* base_subdiv_cube;
@@ -165,6 +166,7 @@ public:
     , 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);

src/slicer.cpp

@@ -887,10 +887,14 @@ 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++)
+
+    std::vector<SlicerLayer>& layers_ref = layers; // force layers not to be copied into the threads
+#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++)
     {
-        layers[layer_nr].makePolygons(mesh, keep_none_closed, extensive_stitching);
+        layers_ref[layer_nr].makePolygons(mesh, keep_none_closed, extensive_stitching);
     }
+
     mesh->expandXY(mesh->getSettingInMicrons("xy_offset"));
     log("slice make polygons took %.3f seconds\n",slice_timer.restart());
 }

src/support.cpp

@@ -90,6 +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];
@@ -100,25 +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);
+        }
+    }
 }
 
 /* 
@@ -156,6 +165,7 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
     const int supportTowerDiameter = mesh.getSettingInMicrons("support_tower_diameter");
     const int supportMinAreaSqrt = mesh.getSettingInMicrons("support_minimal_diameter");
     const double supportTowerRoofAngle = mesh.getSettingInAngleRadians("support_tower_roof_angle");
+    const bool use_towers = mesh.getSettingBoolean("support_use_towers") && supportMinAreaSqrt > 0;
 
     const int layerThickness = storage.getSettingInMicrons("layer_height");
     const int supportXYDistance = mesh.getSettingInMicrons("support_xy_distance");
@@ -225,7 +235,10 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
         
     
     std::vector<std::pair<int, std::vector<Polygons>>> overhang_points; // stores overhang_points along with the layer index at which the overhang point occurs
-    AreaSupport::detectOverhangPoints(storage, mesh, overhang_points, layer_count, supportMinAreaSqrt);
+    if (use_towers)
+    {
+        AreaSupport::detectOverhangPoints(storage, mesh, overhang_points, layer_count, supportMinAreaSqrt);
+    }
 
     std::deque<std::pair<Polygons, Polygons>> basic_and_full_overhang_above;
     for (unsigned int layer_idx = support_layer_count - 1; layer_idx != support_layer_count - 1 - layerZdistanceTop ; layer_idx--)
@@ -255,7 +268,7 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
             supportLayer_this = supportLayer_this.offset(extension_offset);
         }
 
-        if (supportMinAreaSqrt > 0)
+        if (use_towers)
         {
             // handle straight walls
             AreaSupport::handleWallStruts(supportLayer_this, supportMinAreaSqrt, supportTowerDiameter);
@@ -342,14 +355,14 @@ void AreaSupport::generateSupportAreas(SliceDataStorage& storage, unsigned int m
     }
 
     //Enforce top Z distance.
-    if (layerZdistanceTop > 0)
+    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; layer_idx++)
+        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, false));
+            supportAreas[layer_idx] = supportAreas[layer_idx].difference(storage.getLayerOutlines(layer_idx + layerZdistanceTop - 1, false));
         }
     }
 
@@ -559,7 +572,7 @@ 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"));
@@ -576,44 +589,41 @@ 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/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/polygon.cpp

@@ -837,7 +837,6 @@ void PolygonRef::smooth_corner_simple(ListPolygon& poly, const Point p0, const P
             Point b;
             bool success = LinearAlg2D::getPointOnLineWithDist(a, p1, p2, shortcut_length, b);
             // v02 has to be longer than ab!
-            p1_it.remove();
             if (success)
             { // if not success then assume b is negligibly close to 2, but rounding errors caused a problem
 #ifdef ASSERT_INSANE_OUTPUT
@@ -845,6 +844,7 @@ void PolygonRef::smooth_corner_simple(ListPolygon& poly, const Point p0, const P
 #endif // #ifdef ASSERT_INSANE_OUTPUT
                 ListPolyIt::insertPointNonDuplicate(p1_it, p2_it, b);
             }
+            p1_it.remove();
         }
     }
 }

src/utils/string.h

@@ -1,3 +1,6 @@
+//Copyright (c) 2017 Ultimaker B.V.
+//CuraEngine is released under the terms of the AGPLv3 or higher.
+
 #ifndef UTILS_STRING_H
 #define UTILS_STRING_H
 
@@ -35,7 +38,7 @@ static inline void writeInt2mm(const int64_t coord, std::ostream& ss)
 {
     constexpr size_t buffer_size = 24;
     char buffer[buffer_size];
-    int char_count = sprintf(buffer, "%" PRId64, coord); // convert int to string
+    int char_count = sprintf(buffer, "%d", int(coord)); // convert int to string
 #ifdef DEBUG
     if (char_count + 1 >= int(buffer_size)) // + 1 for the null character
     {

tests/runtest.py

@@ -235,11 +235,14 @@ class Setting:
             tree = ast.parse(code, "eval")
             compiled = compile(code, self._key, "eval")
         except (SyntaxError, TypeError) as e:
-            print("Parse error in function (" + code + ") for setting", self._key + ":", str(e))
+            print("Parse error in function (" + str(code) + ") for setting", self._key + ":", str(e))
+            return None
         except IllegalMethodError as e:
             print("Use of illegal method", str(e), "in function (" + code + ") for setting", self._key)
+            return None
         except Exception as e:
             print("Exception in function (" + code + ") for setting", self._key + ":", str(e))
+            return None
 
         return eval(compiled, globals(), locals)