Bugfix: make_perimeters() was not truly idempotent because prepare_infill() split ->slices into typed surfaces

xs/src/Print.cpp

@@ -66,7 +66,8 @@ REGISTER_CLASS(PrintRegion, "Print::Region");
 
 PrintObject::PrintObject(Print* print, ModelObject* model_object, const BoundingBoxf3 &modobj_bbox)
 :   _print(print),
-    _model_object(model_object)
+    _model_object(model_object),
+    typed_slices(false)
 {
     region_volumes.resize(this->_print->regions.size());
 

xs/src/Print.hpp

@@ -70,6 +70,10 @@ class PrintObject
     Points copies;      // Slic3r::Point objects in scaled G-code coordinates
     PrintObjectConfig config;
     t_layer_height_ranges layer_height_ranges;
+    
+    // this is set to true when LayerRegion->slices is split in top/internal/bottom
+    // so that next call to make_perimeters() performs a union() before computing loops
+    bool typed_slices;
 
     Point3 size;           // XYZ in scaled coordinates
 

xs/xsp/Print.xsp

@@ -61,7 +61,12 @@ _constant()
         %code%{ RETVAL = &THIS->size; %};
     Ref<Point> _copies_shift()
         %code%{ RETVAL = &THIS->_copies_shift; %};
-
+    
+    bool typed_slices()
+        %code%{ RETVAL = THIS->typed_slices; %};
+    void set_typed_slices(bool value)
+        %code%{ THIS->typed_slices = value; %};
+    
     Points _shifted_copies()
         %code%{ RETVAL = THIS->_shifted_copies; %};
     void set_shifted_copies(Points value)