Fixed crashes intruduced recently into G-code generator.

Added a template sort_remove_duplicates.

xs/src/libslic3r/GCode.cpp

@@ -802,8 +802,7 @@ void GCode::process_layer(
         // Merge with the skirt extruders.
         for (const auto &ex : skirt_loops_per_extruder)
             extruders.push_back(ex.first);
-        std::sort(extruders.begin(), extruders.end());
+        sort_remove_duplicates(extruders);
-        extruders.erase(std::unique(extruders.begin(), extruders.end()), extruders.end());
     }
     // Reorder the extruders, so that the last used extruder is at the front.
     for (size_t i = 1; i < extruders.size(); ++ i)
@@ -863,25 +862,28 @@ void GCode::process_layer(
             continue;
         for (const ObjectByExtruder &object_by_extruder : objects_by_extruder_it->second) {
             const size_t       layer_id     = &object_by_extruder - objects_by_extruder_it->second.data();
-            const PrintObject &print_object = *layers[layer_id].object();
+            const PrintObject *print_object = layers[layer_id].object();
+			if (print_object == nullptr)
+				// This layer is empty for this particular object, it has neither object extrusions nor support extrusions at this print_z.
+				continue;
             if (m_enable_analyzer_markers) {
                 // Store the binary pointer to the layer object directly into the G-code to be accessed by the GCodeAnalyzer.
                 char buf[64];
                 sprintf(buf, ";_LAYEROBJ:%p\n", m_layer);
                 gcode += buf;
             }
-            m_config.apply(print_object.config, true);
+            m_config.apply(print_object->config, true);
             m_layer = layers[layer_id].layer();
             if (m_config.avoid_crossing_perimeters)
                 m_avoid_crossing_perimeters.init_layer_mp(union_ex(m_layer->slices, true));
             Points copies;
             if (single_object_idx == size_t(-1)) 
-                copies = print_object._shifted_copies;
+                copies = print_object->_shifted_copies;
             else
-                copies.push_back(print_object._shifted_copies[single_object_idx]);
+                copies.push_back(print_object->_shifted_copies[single_object_idx]);
             for (const Point &copy : copies) {
                 // When starting a new object, use the external motion planner for the first travel move.
-                std::pair<const PrintObject*, Point> this_object_copy(&print_object, copy);
+                std::pair<const PrintObject*, Point> this_object_copy(print_object, copy);
                 if (m_last_obj_copy != this_object_copy)
                     m_avoid_crossing_perimeters.use_external_mp_once = true;
                 m_last_obj_copy = this_object_copy;
@@ -916,12 +918,10 @@ void GCode::process_layer(
 
     // Apply cooling logic; this may alter speeds.
     if (m_cooling_buffer)
-        gcode = m_cooling_buffer->append(
+        //FIXME Update the CoolingBuffer class to ignore the object ID, which does not make sense anymore
-            gcode, 
+        // once all extrusions of a layer are processed at once.
-            // Index of the current layer's object
+        // Update the test cases.
-            //FIXME add an index into the objects?
+        gcode = m_cooling_buffer->append(gcode, 0, layer.id(), false);
-            std::find(print.objects.begin(), print.objects.end(), layers.front().object()) - print.objects.begin(),
-            layers.front().layer()->id(), false);
     write(file, this->filter(std::move(gcode), false));
 }
 
@@ -1481,14 +1481,14 @@ std::string GCode::extrude_multi_path(ExtrusionMultiPath multipath, std::string
     return gcode;
 }
 
-std::string GCode::extrude_entity(const ExtrusionEntity &entity, std::string description, double speed)
+std::string GCode::extrude_entity(const ExtrusionEntity &entity, std::string description, double speed, std::unique_ptr<EdgeGrid::Grid> *lower_layer_edge_grid)
 {
     if (const ExtrusionPath* path = dynamic_cast<const ExtrusionPath*>(&entity))
         return this->extrude_path(*path, description, speed);
     else if (const ExtrusionMultiPath* multipath = dynamic_cast<const ExtrusionMultiPath*>(&entity))
         return this->extrude_multi_path(*multipath, description, speed);
     else if (const ExtrusionLoop* loop = dynamic_cast<const ExtrusionLoop*>(&entity))
-        return this->extrude_loop(*loop, description, speed);
+        return this->extrude_loop(*loop, description, speed, lower_layer_edge_grid);
     else {
         CONFESS("Invalid argument supplied to extrude()");
         return "";
@@ -1516,7 +1516,7 @@ std::string GCode::extrude_perimeters(const Print &print, const std::vector<Obje
     for (const ObjectByExtruder::Island::Region &region : by_region) {
         m_config.apply(print.regions[&region - &by_region.front()]->config);
         for (ExtrusionEntity *ee : region.perimeters.entities)
-            gcode += this->extrude_loop(*dynamic_cast<const ExtrusionLoop*>(ee), "perimeter", -1., &lower_layer_edge_grid);
+            gcode += this->extrude_entity(*ee, "perimeter", -1., &lower_layer_edge_grid);
     }
     return gcode;
 }

xs/src/libslic3r/GCode.hpp

@@ -138,7 +138,7 @@ private:
     void            set_extruders(const std::vector<unsigned int> &extruder_ids);
     std::string     preamble();
     std::string     change_layer(coordf_t print_z);
-    std::string     extrude_entity(const ExtrusionEntity &entity, std::string description = "", double speed = -1.);
+    std::string     extrude_entity(const ExtrusionEntity &entity, std::string description = "", double speed = -1., std::unique_ptr<EdgeGrid::Grid> *lower_layer_edge_grid = nullptr);
     std::string     extrude_loop(ExtrusionLoop loop, std::string description, double speed = -1., std::unique_ptr<EdgeGrid::Grid> *lower_layer_edge_grid = nullptr);
     std::string     extrude_multi_path(ExtrusionMultiPath multipath, std::string description = "", double speed = -1.);
     std::string     extrude_path(ExtrusionPath path, std::string description = "", double speed = -1.);

xs/src/libslic3r/Print.cpp

@@ -270,8 +270,7 @@ std::vector<unsigned int> Print::object_extruders() const
             extruders.push_back((*region)->config.solid_infill_extruder - 1);
     }
     
-	std::sort(extruders.begin(), extruders.end());
+    sort_remove_duplicates(extruders);
-    extruders.erase(std::unique(extruders.begin(), extruders.end()), extruders.end());
     return extruders;
 }
 
@@ -298,8 +297,7 @@ std::vector<unsigned int> Print::support_material_extruders() const
         // Add all object extruders to the support extruders as it is not know which one will be used to print supports.
         append(extruders, this->object_extruders());
     
-	std::sort(extruders.begin(), extruders.end());
+    sort_remove_duplicates(extruders);
-	extruders.erase(std::unique(extruders.begin(), extruders.end()), extruders.end());
     return extruders;
 }
 
@@ -308,8 +306,7 @@ std::vector<unsigned int> Print::extruders() const
 {
     std::vector<unsigned int> extruders = this->object_extruders();
     append(extruders, this->support_material_extruders());
-	std::sort(extruders.begin(), extruders.end());
+    sort_remove_duplicates(extruders);
-	extruders.erase(std::unique(extruders.begin(), extruders.end()), extruders.end());
     return extruders;
 }
 

xs/src/libslic3r/libslic3r.h

@@ -100,7 +100,7 @@ inline void append_to(std::vector<T> &dst, const std::vector<T> &src)
 }
 
 template <typename T>
-void append(std::vector<T>& dest, const std::vector<T>& src)
+inline void append(std::vector<T>& dest, const std::vector<T>& src)
 {
     if (dest.empty())
         dest = src;
@@ -109,7 +109,7 @@ void append(std::vector<T>& dest, const std::vector<T>& src)
 }
 
 template <typename T>
-void append(std::vector<T>& dest, std::vector<T>&& src)
+inline void append(std::vector<T>& dest, std::vector<T>&& src)
 {
     if (dest.empty())
         dest = std::move(src);
@@ -120,13 +120,20 @@ void append(std::vector<T>& dest, std::vector<T>&& src)
 }
 
 template <typename T>
-void remove_nulls(std::vector<T*> &vec)
+inline void remove_nulls(std::vector<T*> &vec)
 {
 	vec.erase(
     	std::remove_if(vec.begin(), vec.end(), [](const T *ptr) { return ptr == nullptr; }),
     	vec.end());
 }
 
+template <typename T>
+inline void sort_remove_duplicates(std::vector<T> &vec)
+{
+	std::sort(vec.begin(), vec.end());
+	vec.erase(std::unique(vec.begin(), vec.end()), vec.end());
+}
+
 // Older compilers do not provide a std::make_unique template. Provide a simple one.
 template<typename T, typename... Args>
 inline std::unique_ptr<T> make_unique(Args&&... args) {