Merge branch 'xs-perimetergenerator'

xs/MANIFEST

@@ -1690,6 +1690,8 @@ src/libslic3r/MotionPlanner.cpp
 src/libslic3r/MotionPlanner.hpp
 src/libslic3r/MultiPoint.cpp
 src/libslic3r/MultiPoint.hpp
+src/libslic3r/PerimeterGenerator.cpp
+src/libslic3r/PerimeterGenerator.hpp
 src/libslic3r/PlaceholderParser.cpp
 src/libslic3r/PlaceholderParser.hpp
 src/libslic3r/Point.cpp
@@ -1774,6 +1776,7 @@ xsp/Model.xsp
 xsp/MotionPlanner.xsp
 xsp/my.map
 xsp/mytype.map
+xsp/PerimeterGenerator.xsp
 xsp/PlaceholderParser.xsp
 xsp/Point.xsp
 xsp/Polygon.xsp

xs/src/libslic3r/ClipperUtils.cpp

@@ -136,6 +136,15 @@ offset(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float d
     ClipperPaths_to_Slic3rMultiPoints(output, retval);
 }
 
+Slic3r::Polygons
+offset(const Slic3r::Polygons &polygons, const float delta,
+    double scale, ClipperLib::JoinType joinType, double miterLimit)
+{
+    Slic3r::Polygons pp;
+    offset(polygons, &pp, delta, scale, joinType, miterLimit);
+    return pp;
+}
+
 void
 offset(const Slic3r::Polylines &polylines, ClipperLib::Paths* retval, const float delta,
     double scale, ClipperLib::JoinType joinType, double miterLimit)
@@ -248,6 +257,15 @@ offset2(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float
     ClipperPaths_to_Slic3rMultiPoints(output, retval);
 }
 
+Slic3r::Polygons
+offset2(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+{
+    Slic3r::Polygons pp;
+    offset2(polygons, &pp, delta1, delta2, scale, joinType, miterLimit);
+    return pp;
+}
+
 void
 offset2(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float delta1,
     const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
@@ -260,6 +278,15 @@ offset2(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const floa
     ClipperPaths_to_Slic3rExPolygons(output, retval);
 }
 
+Slic3r::ExPolygons
+offset2_ex(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+{
+    Slic3r::ExPolygons expp;
+    offset2(polygons, &expp, delta1, delta2, scale, joinType, miterLimit);
+    return expp;
+}
+
 template <class T>
 void _clipper_do(const ClipperLib::ClipType clipType, const Slic3r::Polygons &subject, 
     const Slic3r::Polygons &clip, T* retval, const ClipperLib::PolyFillType fillType, const bool safety_offset_)
@@ -437,6 +464,22 @@ void diff(const SubjectType &subject, const Slic3r::ExPolygons &clip, ResultType
 }
 template void diff<Slic3r::Polygons, Slic3r::ExPolygons>(const Slic3r::Polygons &subject, const Slic3r::ExPolygons &clip, Slic3r::ExPolygons* retval, bool safety_offset_);
 
+Slic3r::Polygons
+diff(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_)
+{
+    Slic3r::Polygons pp;
+    diff(subject, clip, &pp, safety_offset_);
+    return pp;
+}
+
+Slic3r::ExPolygons
+diff_ex(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_)
+{
+    Slic3r::ExPolygons expp;
+    diff(subject, clip, &expp, safety_offset_);
+    return expp;
+}
+
 template <class SubjectType, class ResultType>
 void intersection(const SubjectType &subject, const Slic3r::Polygons &clip, ResultType* retval, bool safety_offset_)
 {
@@ -448,6 +491,22 @@ template void intersection<Slic3r::Polygons, Slic3r::Polylines>(const Slic3r::Po
 template void intersection<Slic3r::Polylines, Slic3r::Polylines>(const Slic3r::Polylines &subject, const Slic3r::Polygons &clip, Slic3r::Polylines* retval, bool safety_offset_);
 template void intersection<Slic3r::Lines, Slic3r::Lines>(const Slic3r::Lines &subject, const Slic3r::Polygons &clip, Slic3r::Lines* retval, bool safety_offset_);
 
+Slic3r::Polygons
+intersection(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_)
+{
+    Slic3r::Polygons pp;
+    intersection(subject, clip, &pp, safety_offset_);
+    return pp;
+}
+
+Slic3r::Polylines
+intersection(const Slic3r::Polylines &subject, const Slic3r::Polygons &clip, bool safety_offset_)
+{
+    Slic3r::Polylines pp;
+    intersection(subject, clip, &pp, safety_offset_);
+    return pp;
+}
+
 template <class SubjectType>
 bool intersects(const SubjectType &subject, const Slic3r::Polygons &clip, bool safety_offset_)
 {
@@ -474,6 +533,22 @@ void union_(const Slic3r::Polygons &subject, T* retval, bool safety_offset_)
 template void union_<Slic3r::ExPolygons>(const Slic3r::Polygons &subject, Slic3r::ExPolygons* retval, bool safety_offset_);
 template void union_<Slic3r::Polygons>(const Slic3r::Polygons &subject, Slic3r::Polygons* retval, bool safety_offset_);
 
+Slic3r::Polygons
+union_(const Slic3r::Polygons &subject, bool safety_offset)
+{
+    Polygons pp;
+    union_(subject, &pp, safety_offset);
+    return pp;
+}
+
+Slic3r::ExPolygons
+union_ex(const Slic3r::Polygons &subject, bool safety_offset)
+{
+    ExPolygons expp;
+    union_(subject, &expp, safety_offset);
+    return expp;
+}
+
 void union_(const Slic3r::Polygons &subject1, const Slic3r::Polygons &subject2, Slic3r::Polygons* retval, bool safety_offset)
 {
     Polygons pp = subject1;

xs/src/libslic3r/ClipperUtils.hpp

@@ -40,6 +40,9 @@ void offset(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const f
 void offset(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float delta,
     double scale = 100000, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
+Slic3r::Polygons offset(const Slic3r::Polygons &polygons, const float delta,
+    double scale = 100000, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
 
 // offset Polylines
 void offset(const Slic3r::Polylines &polylines, ClipperLib::Paths* retval, const float delta,
@@ -62,9 +65,15 @@ void offset2(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const
 void offset2(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float delta1,
     const float delta2, double scale = 100000, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
+Slic3r::Polygons offset2(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, double scale = 100000, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
 void offset2(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float delta1,
     const float delta2, double scale = 100000, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
+Slic3r::ExPolygons offset2_ex(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, double scale = 100000, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
 
 template <class T>
 void _clipper_do(ClipperLib::ClipType clipType, const Slic3r::Polygons &subject, 
@@ -86,9 +95,15 @@ void diff(const SubjectType &subject, const Slic3r::Polygons &clip, ResultType*
 template <class SubjectType, class ResultType>
 void diff(const SubjectType &subject, const Slic3r::ExPolygons &clip, ResultType* retval, bool safety_offset_ = false);
 
+Slic3r::Polygons diff(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+Slic3r::ExPolygons diff_ex(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+
 template <class SubjectType, class ResultType>
 void intersection(const SubjectType &subject, const Slic3r::Polygons &clip, ResultType* retval, bool safety_offset_ = false);
 
+Slic3r::Polygons intersection(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+Slic3r::Polylines intersection(const Slic3r::Polylines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+
 template <class SubjectType>
 bool intersects(const SubjectType &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
 
@@ -98,6 +113,9 @@ void xor_(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, Slic3r:
 template <class T>
 void union_(const Slic3r::Polygons &subject, T* retval, bool safety_offset_ = false);
 
+Slic3r::Polygons union_(const Slic3r::Polygons &subject, bool safety_offset = false);
+Slic3r::ExPolygons union_ex(const Slic3r::Polygons &subject, bool safety_offset = false);
+
 void union_(const Slic3r::Polygons &subject1, const Slic3r::Polygons &subject2, Slic3r::Polygons* retval, bool safety_offset = false);
 
 void union_pt(const Slic3r::Polygons &subject, ClipperLib::PolyTree* retval, bool safety_offset_ = false);

xs/src/libslic3r/ExPolygon.cpp

@@ -122,6 +122,13 @@ ExPolygon::has_boundary_point(const Point &point) const
     return false;
 }
 
+void
+ExPolygon::simplify_p(double tolerance, Polygons* polygons) const
+{
+    Polygons pp = this->simplify_p(tolerance);
+    polygons->insert(polygons->end(), pp.begin(), pp.end());
+}
+
 Polygons
 ExPolygon::simplify_p(double tolerance) const
 {
@@ -180,16 +187,17 @@ ExPolygon::medial_axis(double max_width, double min_width, Polylines* polylines)
     }
     
     // compute the Voronoi diagram
-    ma.build(polylines);
+    Polylines pp;
+    ma.build(&pp);
     
     // clip segments to our expolygon area
     // (do this before extending endpoints as external segments coule be extended into
     // expolygon, this leaving wrong things inside)
-    intersection(*polylines, *this, polylines);
+    pp = intersection(pp, *this);
     
     // extend initial and final segments of each polyline (they will be clipped)
     // unless they represent closed loops
-    for (Polylines::iterator polyline = polylines->begin(); polyline != polylines->end(); ++polyline) {
+    for (Polylines::iterator polyline = pp.begin(); polyline != pp.end(); ++polyline) {
         if (polyline->points.front().distance_to(polyline->points.back()) < min_width) continue;
         // TODO: we should *not* extend endpoints where other polylines start/end
         // (such as T joints, which are returned as three polylines by MedialAxis)
@@ -198,18 +206,20 @@ ExPolygon::medial_axis(double max_width, double min_width, Polylines* polylines)
     }
     
     // clip again after extending endpoints to prevent them from exceeding the expolygon boundaries
-    intersection(*polylines, *this, polylines);
+    pp = intersection(pp, *this);
     
     // remove too short polylines
     // (we can't do this check before endpoints extension and clipping because we don't
     // know how long will the endpoints be extended since it depends on polygon thickness
     // which is variable - extension will be <= max_width/2 on each side)
-    for (size_t i = 0; i < polylines->size(); ++i) {
-        if ((*polylines)[i].length() < max_width) {
-            polylines->erase(polylines->begin() + i);
+    for (size_t i = 0; i < pp.size(); ++i) {
+        if (pp[i].length() < max_width) {
+            pp.erase(pp.begin() + i);
             --i;
         }
     }
+    
+    polylines->insert(polylines->end(), pp.begin(), pp.end());
 }
 
 void

xs/src/libslic3r/ExPolygon.hpp

@@ -27,6 +27,7 @@ class ExPolygon
     bool contains(const Point &point) const;
     bool contains_b(const Point &point) const;
     bool has_boundary_point(const Point &point) const;
+    void simplify_p(double tolerance, Polygons* polygons) const;
     Polygons simplify_p(double tolerance) const;
     ExPolygons simplify(double tolerance) const;
     void simplify(double tolerance, ExPolygons &expolygons) const;

xs/src/libslic3r/ExtrusionEntity.hpp

@@ -52,6 +52,7 @@ class ExtrusionEntity
     virtual Point last_point() const = 0;
     virtual Polygons grow() const = 0;
     virtual double min_mm3_per_mm() const = 0;
+    virtual Polyline as_polyline() const = 0;
 };
 
 typedef std::vector<ExtrusionEntity*> ExtrusionEntitiesPtr;
@@ -83,6 +84,9 @@ class ExtrusionPath : public ExtrusionEntity
     double min_mm3_per_mm() const {
         return this->mm3_per_mm;
     };
+    Polyline as_polyline() const {
+        return this->polyline;
+    };
 
     private:
     void _inflate_collection(const Polylines &polylines, ExtrusionEntityCollection* collection) const;
@@ -97,6 +101,8 @@ class ExtrusionLoop : public ExtrusionEntity
     ExtrusionLoopRole role;
     
     ExtrusionLoop(ExtrusionLoopRole role = elrDefault) : role(role) {};
+    ExtrusionLoop(const ExtrusionPaths &paths, ExtrusionLoopRole role = elrDefault)
+        : paths(paths), role(role) {};
     bool is_loop() const {
         return true;
     };
@@ -120,6 +126,9 @@ class ExtrusionLoop : public ExtrusionEntity
     bool is_solid_infill() const;
     Polygons grow() const;
     double min_mm3_per_mm() const;
+    Polyline as_polyline() const {
+        return this->polygon().split_at_first_point();
+    };
 };
 
 }

xs/src/libslic3r/ExtrusionEntityCollection.cpp

@@ -8,9 +8,13 @@ namespace Slic3r {
 ExtrusionEntityCollection::ExtrusionEntityCollection(const ExtrusionEntityCollection& collection)
     : no_sort(collection.no_sort), orig_indices(collection.orig_indices)
 {
-    this->entities.reserve(collection.entities.size());
-    for (ExtrusionEntitiesPtr::const_iterator it = collection.entities.begin(); it != collection.entities.end(); ++it)
-        this->entities.push_back((*it)->clone());
+    this->append(collection.entities);
+}
+
+ExtrusionEntityCollection::ExtrusionEntityCollection(const ExtrusionPaths &paths)
+    : no_sort(false)
+{
+    this->append(paths);
 }
 
 ExtrusionEntityCollection& ExtrusionEntityCollection::operator= (const ExtrusionEntityCollection &other)
@@ -28,10 +32,30 @@ ExtrusionEntityCollection::swap (ExtrusionEntityCollection &c)
     std::swap(this->no_sort, c.no_sort);
 }
 
+ExtrusionEntityCollection::~ExtrusionEntityCollection()
+{
+    for (ExtrusionEntitiesPtr::iterator it = this->entities.begin(); it != this->entities.end(); ++it)
+        delete *it;
+}
+
+ExtrusionEntityCollection::operator ExtrusionPaths() const
+{
+    ExtrusionPaths paths;
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
+        if (const ExtrusionPath* path = dynamic_cast<const ExtrusionPath*>(*it))
+            paths.push_back(*path);
+    }
+    return paths;
+}
+
 ExtrusionEntityCollection*
 ExtrusionEntityCollection::clone() const
 {
-    return new ExtrusionEntityCollection(*this);
+    ExtrusionEntityCollection* coll = new ExtrusionEntityCollection(*this);
+    for (size_t i = 0; i < coll->entities.size(); ++i) {
+        coll->entities[i] = this->entities[i]->clone();
+    }
+    return coll;
 }
 
 void
@@ -57,6 +81,34 @@ ExtrusionEntityCollection::last_point() const
     return this->entities.back()->last_point();
 }
 
+void
+ExtrusionEntityCollection::append(const ExtrusionEntity &entity)
+{
+    this->entities.push_back(entity.clone());
+}
+
+void
+ExtrusionEntityCollection::append(const ExtrusionEntitiesPtr &entities)
+{
+    for (ExtrusionEntitiesPtr::const_iterator ptr = entities.begin(); ptr != entities.end(); ++ptr)
+        this->append(**ptr);
+}
+
+void
+ExtrusionEntityCollection::append(const ExtrusionPaths &paths)
+{
+    for (ExtrusionPaths::const_iterator path = paths.begin(); path != paths.end(); ++path)
+        this->append(*path);
+}
+
+ExtrusionEntityCollection
+ExtrusionEntityCollection::chained_path(bool no_reverse, std::vector<size_t>* orig_indices) const
+{
+    ExtrusionEntityCollection coll;
+    this->chained_path(&coll, no_reverse, orig_indices);
+    return coll;
+}
+
 void
 ExtrusionEntityCollection::chained_path(ExtrusionEntityCollection* retval, bool no_reverse, std::vector<size_t>* orig_indices) const
 {
@@ -145,15 +197,21 @@ ExtrusionEntityCollection::flatten(ExtrusionEntityCollection* retval) const
     for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
         if ((*it)->is_collection()) {
             ExtrusionEntityCollection* collection = dynamic_cast<ExtrusionEntityCollection*>(*it);
-            ExtrusionEntityCollection contents;
-            collection->flatten(&contents);
-            retval->entities.insert(retval->entities.end(), contents.entities.begin(), contents.entities.end());
+            retval->append(collection->flatten().entities);
         } else {
-            retval->entities.push_back((*it)->clone());
+            retval->append(**it);
         }
     }
 }
 
+ExtrusionEntityCollection
+ExtrusionEntityCollection::flatten() const
+{
+    ExtrusionEntityCollection coll;
+    this->flatten(&coll);
+    return coll;
+}
+
 double
 ExtrusionEntityCollection::min_mm3_per_mm() const
 {

xs/src/libslic3r/ExtrusionEntityCollection.hpp

@@ -10,19 +10,30 @@ class ExtrusionEntityCollection : public ExtrusionEntity
 {
     public:
     ExtrusionEntityCollection* clone() const;
-    ExtrusionEntitiesPtr entities;
+    ExtrusionEntitiesPtr entities;     // we own these entities
     std::vector<size_t> orig_indices;  // handy for XS
     bool no_sort;
     ExtrusionEntityCollection(): no_sort(false) {};
     ExtrusionEntityCollection(const ExtrusionEntityCollection &collection);
+    ExtrusionEntityCollection(const ExtrusionPaths &paths);
     ExtrusionEntityCollection& operator= (const ExtrusionEntityCollection &other);
+    ~ExtrusionEntityCollection();
+    operator ExtrusionPaths() const;
+    
     bool is_collection() const {
         return true;
     };
     bool can_reverse() const {
         return !this->no_sort;
     };
+    bool empty() const {
+        return this->entities.empty();
+    };
     void swap (ExtrusionEntityCollection &c);
+    void append(const ExtrusionEntity &entity);
+    void append(const ExtrusionEntitiesPtr &entities);
+    void append(const ExtrusionPaths &paths);
+    ExtrusionEntityCollection chained_path(bool no_reverse = false, std::vector<size_t>* orig_indices = NULL) const;
     void chained_path(ExtrusionEntityCollection* retval, bool no_reverse = false, std::vector<size_t>* orig_indices = NULL) const;
     void chained_path_from(Point start_near, ExtrusionEntityCollection* retval, bool no_reverse = false, std::vector<size_t>* orig_indices = NULL) const;
     void reverse();
@@ -31,7 +42,12 @@ class ExtrusionEntityCollection : public ExtrusionEntity
     Polygons grow() const;
     size_t items_count() const;
     void flatten(ExtrusionEntityCollection* retval) const;
+    ExtrusionEntityCollection flatten() const;
     double min_mm3_per_mm() const;
+    Polyline as_polyline() const {
+        CONFESS("Calling as_polyline() on a ExtrusionEntityCollection");
+        return Polyline();
+    };
 };
 
 }

xs/src/libslic3r/PerimeterGenerator.cpp

@@ -0,0 +1,525 @@
+#include "PerimeterGenerator.hpp"
+#include "ClipperUtils.hpp"
+#include "ExtrusionEntityCollection.hpp"
+
+namespace Slic3r {
+
+void
+PerimeterGenerator::process()
+{
+    // other perimeters
+    this->_mm3_per_mm           = this->perimeter_flow.mm3_per_mm();
+    coord_t pwidth              = this->perimeter_flow.scaled_width();
+    coord_t pspacing            = this->perimeter_flow.scaled_spacing();
+    
+    // external perimeters
+    this->_ext_mm3_per_mm       = this->ext_perimeter_flow.mm3_per_mm();
+    coord_t ext_pwidth        = this->ext_perimeter_flow.scaled_width();
+    coord_t ext_pspacing      = scale_(this->ext_perimeter_flow.spacing(this->perimeter_flow));
+    
+    // overhang perimeters
+    this->_mm3_per_mm_overhang  = this->overhang_flow.mm3_per_mm();
+    
+    // solid infill
+    coord_t ispacing            = this->solid_infill_flow.scaled_spacing();
+    coord_t gap_area_threshold  = pwidth * pwidth;
+    
+    // Calculate the minimum required spacing between two adjacent traces.
+    // This should be equal to the nominal flow spacing but we experiment
+    // with some tolerance in order to avoid triggering medial axis when
+    // some squishing might work. Loops are still spaced by the entire
+    // flow spacing; this only applies to collapsing parts.
+    coord_t min_spacing         = pspacing      * (1 - INSET_OVERLAP_TOLERANCE);
+    coord_t ext_min_spacing     = ext_pspacing  * (1 - INSET_OVERLAP_TOLERANCE);
+    
+    // prepare grown lower layer slices for overhang detection
+    if (this->lower_slices != NULL && this->config->overhangs) {
+        // We consider overhang any part where the entire nozzle diameter is not supported by the
+        // lower layer, so we take lower slices and offset them by half the nozzle diameter used 
+        // in the current layer
+        double nozzle_diameter = this->print_config->nozzle_diameter.get_at(this->config->perimeter_extruder-1);
+        
+        this->_lower_slices_p = offset(*this->lower_slices, scale_(+nozzle_diameter/2));
+    }
+    
+    // we need to process each island separately because we might have different
+    // extra perimeters for each one
+    for (Surfaces::const_iterator surface = this->slices->surfaces.begin();
+        surface != this->slices->surfaces.end(); ++surface) {
+        // detect how many perimeters must be generated for this island
+        unsigned short loop_number = this->config->perimeters + surface->extra_perimeters;
+        loop_number--;  // 0-indexed loops
+        
+        Polygons gaps;
+        
+        Polygons last = surface->expolygon.simplify_p(SCALED_RESOLUTION);
+        if (loop_number >= 0) {  // no loops = -1
+            
+            std::vector<PerimeterGeneratorLoops> contours(loop_number+1);    // depth => loops
+            std::vector<PerimeterGeneratorLoops> holes(loop_number+1);       // depth => loops
+            Polylines thin_walls;
+            
+            // we loop one time more than needed in order to find gaps after the last perimeter was applied
+            for (unsigned short i = 0; i <= loop_number+1; ++i) {  // outer loop is 0
+                Polygons offsets;
+                if (i == 0) {
+                    // the minimum thickness of a single loop is:
+                    // ext_width/2 + ext_spacing/2 + spacing/2 + width/2
+                    if (this->config->thin_walls) {
+                        offsets = offset2(
+                            last,
+                            -(0.5*ext_pwidth + 0.5*ext_min_spacing - 1),
+                            +(0.5*ext_min_spacing - 1)
+                        );
+                    } else {
+                        offsets = offset(last, -0.5*ext_pwidth);
+                    }
+                    
+                    // look for thin walls
+                    if (this->config->thin_walls) {
+                        Polygons diffpp = diff(
+                            last,
+                            offset(offsets, +0.5*ext_pwidth),
+                            true  // medial axis requires non-overlapping geometry
+                        );
+                        
+                        // the following offset2 ensures almost nothing in @thin_walls is narrower than $min_width
+                        // (actually, something larger than that still may exist due to mitering or other causes)
+                        coord_t min_width = ext_pwidth / 2;
+                        ExPolygons expp = offset2_ex(diffpp, -min_width/2, +min_width/2);
+                        
+                        // the maximum thickness of our thin wall area is equal to the minimum thickness of a single loop
+                        Polylines pp;
+                        for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex)
+                            ex->medial_axis(ext_pwidth + ext_pspacing, min_width, &pp);
+                        
+                        double threshold = ext_pwidth * ext_pwidth;
+                        for (Polylines::const_iterator p = pp.begin(); p != pp.end(); ++p) {
+                            if (p->length() > threshold) {
+                                thin_walls.push_back(*p);
+                            }
+                        }
+                        
+                        #ifdef DEBUG
+                        printf("  %zu thin walls detected\n", thin_walls.size());
+                        #endif
+                        
+                        /*
+                        if (false) {
+                            require "Slic3r/SVG.pm";
+                            Slic3r::SVG::output(
+                                "medial_axis.svg",
+                                no_arrows       => 1,
+                                #expolygons      => \@expp,
+                                polylines       => \@thin_walls,
+                            );
+                        }
+                        */
+                    }
+                } else {
+                    coord_t distance = (i == 1) ? ext_pspacing : pspacing;
+                    
+                    if (this->config->thin_walls) {
+                        offsets = offset2(
+                            last,
+                            -(distance + 0.5*min_spacing - 1),
+                            +(0.5*min_spacing - 1)
+                        );
+                    } else {
+                        offsets = offset(
+                            last,
+                            -distance
+                        );
+                    }
+                    
+                    // look for gaps
+                    if (this->config->gap_fill_speed.value > 0 && this->config->fill_density.value > 0) {
+                        // not using safety offset here would "detect" very narrow gaps
+                        // (but still long enough to escape the area threshold) that gap fill
+                        // won't be able to fill but we'd still remove from infill area
+                        ExPolygons diff_expp = diff_ex(
+                            offset(last, -0.5*distance),
+                            offset(offsets, +0.5*distance + 10)  // safety offset
+                        );
+                        for (ExPolygons::const_iterator ex = diff_expp.begin(); ex != diff_expp.end(); ++ex) {
+                            if (fabs(ex->area()) >= gap_area_threshold) {
+                                Polygons pp = *ex;
+                                gaps.insert(gaps.end(), pp.begin(), pp.end());
+                            }
+                        }
+                    }
+                }
+                
+                if (offsets.empty()) break;
+                if (i > loop_number) break; // we were only looking for gaps this time
+                
+                last = offsets;
+                for (Polygons::const_iterator polygon = offsets.begin(); polygon != offsets.end(); ++polygon) {
+                    PerimeterGeneratorLoop loop(*polygon, i);
+                    loop.is_contour = polygon->is_counter_clockwise();
+                    if (loop.is_contour) {
+                        contours[i].push_back(loop);
+                    } else {
+                        holes[i].push_back(loop);
+                    }
+                }
+            }
+            
+            // nest loops: holes first
+            for (unsigned short d = 0; d <= loop_number; ++d) {
+                PerimeterGeneratorLoops &holes_d = holes[d];
+                
+                // loop through all holes having depth == d
+                for (unsigned short i = 0; i < holes_d.size(); ++i) {
+                    const PerimeterGeneratorLoop &loop = holes_d[i];
+                    
+                    // find the hole loop that contains this one, if any
+                    for (unsigned short t = d+1; t <= loop_number; ++t) {
+                        for (unsigned short j = 0; j < holes[t].size(); ++j) {
+                            PerimeterGeneratorLoop &candidate_parent = holes[t][j];
+                            if (candidate_parent.polygon.contains(loop.polygon.first_point())) {
+                                candidate_parent.children.push_back(loop);
+                                holes_d.erase(holes_d.begin() + i);
+                                --i;
+                                goto NEXT_LOOP;
+                            }
+                        }
+                    }
+                
+                    // if no hole contains this hole, find the contour loop that contains it
+                    for (unsigned short t = loop_number; t >= 0; --t) {
+                        for (unsigned short j = 0; j < contours[t].size(); ++j) {
+                            PerimeterGeneratorLoop &candidate_parent = contours[t][j];
+                            if (candidate_parent.polygon.contains(loop.polygon.first_point())) {
+                                candidate_parent.children.push_back(loop);
+                                holes_d.erase(holes_d.begin() + i);
+                                --i;
+                                goto NEXT_LOOP;
+                            }
+                        }
+                    }
+                    NEXT_LOOP: ;
+                }
+            }
+        
+            // nest contour loops
+            for (unsigned short d = loop_number; d >= 1; --d) {
+                PerimeterGeneratorLoops &contours_d = contours[d];
+                
+                // loop through all contours having depth == d
+                for (unsigned short i = 0; i < contours_d.size(); ++i) {
+                    const PerimeterGeneratorLoop &loop = contours_d[i];
+                
+                    // find the contour loop that contains it
+                    for (unsigned short t = d-1; t >= 0; --t) {
+                        for (unsigned short j = 0; j < contours[t].size(); ++j) {
+                            PerimeterGeneratorLoop &candidate_parent = contours[t][j];
+                            if (candidate_parent.polygon.contains(loop.polygon.first_point())) {
+                                candidate_parent.children.push_back(loop);
+                                contours_d.erase(contours_d.begin() + i);
+                                --i;
+                                goto NEXT_CONTOUR;
+                            }
+                        }
+                    }
+                    
+                    NEXT_CONTOUR: ;
+                }
+            }
+        
+            // at this point, all loops should be in contours[0]
+            
+            ExtrusionEntityCollection entities = this->_traverse_loops(contours.front(), thin_walls);
+            
+            // if brim will be printed, reverse the order of perimeters so that
+            // we continue inwards after having finished the brim
+            // TODO: add test for perimeter order
+            if (this->config->external_perimeters_first
+                || (this->layer_id == 0 && this->print_config->brim_width.value > 0))
+                    entities.reverse();
+        
+            // append perimeters for this slice as a collection
+            if (!entities.empty())
+                this->loops->append(entities);
+        }
+        
+        // fill gaps
+        if (!gaps.empty()) {
+            /*
+            if (false) {
+                require "Slic3r/SVG.pm";
+                Slic3r::SVG::output(
+                    "gaps.svg",
+                    expolygons => union_ex(\@gaps),
+                );
+            }
+            */
+            
+            // where $pwidth < thickness < 2*$pspacing, infill with width = 2*$pwidth
+            // where 0.1*$pwidth < thickness < $pwidth, infill with width = 1*$pwidth
+            std::vector<PerimeterGeneratorGapSize> gap_sizes;
+            gap_sizes.push_back(PerimeterGeneratorGapSize(pwidth, 2*pspacing, unscale(2*pwidth)));
+            gap_sizes.push_back(PerimeterGeneratorGapSize(0.1*pwidth, pwidth, unscale(1*pwidth)));
+            
+            for (std::vector<PerimeterGeneratorGapSize>::const_iterator gap_size = gap_sizes.begin();
+                gap_size != gap_sizes.end(); ++gap_size) {
+                ExtrusionEntityCollection gap_fill = this->_fill_gaps(gap_size->min, 
+                    gap_size->max, gap_size->width, gaps);
+                this->gap_fill->append(gap_fill.entities);
+                
+                // Make sure we don't infill narrow parts that are already gap-filled
+                // (we only consider this surface's gaps to reduce the diff() complexity).
+                // Growing actual extrusions ensures that gaps not filled by medial axis
+                // are not subtracted from fill surfaces (they might be too short gaps
+                // that medial axis skips but infill might join with other infill regions
+                // and use zigzag).
+                double dist = scale_(gap_size->width/2);
+                Polygons filled;
+                for (ExtrusionEntitiesPtr::const_iterator it = gap_fill.entities.begin();
+                    it != gap_fill.entities.end(); ++it)
+                    offset((*it)->as_polyline(), &filled, dist);
+                
+                last = diff(last, filled);
+                gaps = diff(gaps, filled);  // prevent more gap fill here
+            }
+        }
+        
+        // create one more offset to be used as boundary for fill
+        // we offset by half the perimeter spacing (to get to the actual infill boundary)
+        // and then we offset back and forth by half the infill spacing to only consider the
+        // non-collapsing regions
+        coord_t inset = 0;
+        if (loop_number == 0) {
+            // one loop
+            inset += ext_pspacing/2;
+        } else if (loop_number > 0) {
+            // two or more loops
+            inset += pspacing/2;
+        }
+        
+        // only apply infill overlap if we actually have one perimeter
+        if (inset > 0)
+            inset -= this->config->get_abs_value("infill_overlap", inset + ispacing/2);
+        
+        {
+            ExPolygons expp = union_ex(last);
+            
+            // simplify infill contours according to resolution
+            Polygons pp;
+            for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex)
+                ex->simplify_p(SCALED_RESOLUTION, &pp);
+            
+            // collapse too narrow infill areas
+            coord_t min_perimeter_infill_spacing = ispacing * (1 - INSET_OVERLAP_TOLERANCE);
+            expp = offset2_ex(
+                pp,
+                -inset -min_perimeter_infill_spacing/2,
+                +min_perimeter_infill_spacing/2
+            );
+            
+            // append infill areas to fill_surfaces
+            for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex)
+                this->fill_surfaces->surfaces.push_back(Surface(stInternal, *ex));  // use a bogus surface type
+        }
+    }
+}
+
+ExtrusionEntityCollection
+PerimeterGenerator::_traverse_loops(const PerimeterGeneratorLoops &loops,
+    Polylines &thin_walls) const
+{
+    // loops is an arrayref of ::Loop objects
+    // turn each one into an ExtrusionLoop object
+    ExtrusionEntityCollection coll;
+    for (PerimeterGeneratorLoops::const_iterator loop = loops.begin();
+        loop != loops.end(); ++loop) {
+        bool is_external = loop->is_external();
+        
+        ExtrusionRole role;
+        ExtrusionLoopRole loop_role;
+        role = is_external ? erExternalPerimeter : erPerimeter;
+        if (loop->is_internal_contour()) {
+            // Note that we set loop role to ContourInternalPerimeter
+            // also when loop is both internal and external (i.e.
+            // there's only one contour loop).
+            loop_role = elrContourInternalPerimeter;
+        } else {
+            loop_role = elrDefault;
+        }
+        
+        // detect overhanging/bridging perimeters
+        ExtrusionPaths paths;
+        if (this->config->overhangs && this->layer_id > 0
+            && !(this->object_config->support_material && this->object_config->support_material_contact_distance.value == 0)) {
+            // get non-overhang paths by intersecting this loop with the grown lower slices
+            {
+                Polylines polylines;
+                intersection((Polygons)loop->polygon, this->_lower_slices_p, &polylines);
+                
+                for (Polylines::const_iterator polyline = polylines.begin(); polyline != polylines.end(); ++polyline) {
+                    ExtrusionPath path(role);
+                    path.polyline   = *polyline;
+                    path.mm3_per_mm = is_external ? this->_ext_mm3_per_mm           : this->_mm3_per_mm;
+                    path.width      = is_external ? this->ext_perimeter_flow.width  : this->perimeter_flow.width;
+                    path.height     = this->layer_height;
+                    paths.push_back(path);
+                }
+            }
+            
+            // get overhang paths by checking what parts of this loop fall 
+            // outside the grown lower slices (thus where the distance between
+            // the loop centerline and original lower slices is >= half nozzle diameter
+            {
+                Polylines polylines;
+                diff((Polygons)loop->polygon, this->_lower_slices_p, &polylines);
+                
+                for (Polylines::const_iterator polyline = polylines.begin(); polyline != polylines.end(); ++polyline) {
+                    ExtrusionPath path(erOverhangPerimeter);
+                    path.polyline   = *polyline;
+                    path.mm3_per_mm = this->_mm3_per_mm_overhang;
+                    path.width      = this->overhang_flow.width;
+                    path.height     = this->overhang_flow.height;
+                    paths.push_back(path);
+                }
+            }
+            
+            // reapply the nearest point search for starting point
+            // We allow polyline reversal because Clipper may have randomly
+            // reversed polylines during clipping.
+            paths = ExtrusionEntityCollection(paths).chained_path();
+        } else {
+            ExtrusionPath path(role);
+            path.polyline   = loop->polygon.split_at_first_point();
+            path.mm3_per_mm = is_external ? this->_ext_mm3_per_mm           : this->_mm3_per_mm;
+            path.width      = is_external ? this->ext_perimeter_flow.width  : this->perimeter_flow.width;
+            path.height     = this->layer_height;
+            paths.push_back(path);
+        }
+        
+        coll.append(ExtrusionLoop(paths, loop_role));
+    }
+    
+    // append thin walls to the nearest-neighbor search (only for first iteration)
+    if (!thin_walls.empty()) {
+        for (Polylines::const_iterator polyline = thin_walls.begin(); polyline != thin_walls.end(); ++polyline) {
+            ExtrusionPath path(erExternalPerimeter);
+            path.polyline   = *polyline;
+            path.mm3_per_mm = this->_mm3_per_mm;
+            path.width      = this->perimeter_flow.width;
+            path.height     = this->layer_height;
+            coll.append(path);
+        }
+        
+        thin_walls.clear();
+    }
+    
+    // sort entities
+    ExtrusionEntityCollection sorted_coll;
+    coll.chained_path(&sorted_coll, false, &sorted_coll.orig_indices);
+    
+    // traverse children
+    ExtrusionEntityCollection entities;
+    for (unsigned short i = 0; i < sorted_coll.orig_indices.size(); ++i) {
+        size_t idx = sorted_coll.orig_indices[i];
+        if (idx >= loops.size()) {
+            // this is a thin wall
+            // let's get it from the sorted collection as it might have been reversed
+            entities.append(*sorted_coll.entities[i]);
+        } else {
+            const PerimeterGeneratorLoop &loop = loops[i];
+            ExtrusionLoop eloop = *dynamic_cast<ExtrusionLoop*>(coll.entities[idx]);
+            
+            ExtrusionEntityCollection children = this->_traverse_loops(loop.children, thin_walls);
+            if (loop.is_contour) {
+                eloop.make_counter_clockwise();
+                entities.append(children.entities);
+                entities.append(eloop);
+            } else {
+                eloop.make_clockwise();
+                entities.append(eloop);
+                entities.append(children.entities);
+            }
+        }
+    }
+    return entities;
+}
+
+ExtrusionEntityCollection
+PerimeterGenerator::_fill_gaps(double min, double max, double w,
+    const Polygons &gaps) const
+{
+    ExtrusionEntityCollection coll;
+    
+    min *= (1 - INSET_OVERLAP_TOLERANCE);
+    
+    ExPolygons curr = diff_ex(
+        offset2(gaps, -min/2, +min/2),
+        offset2(gaps, -max/2, +max/2),
+        true
+    );
+    
+    Polylines polylines;
+    for (ExPolygons::const_iterator ex = curr.begin(); ex != curr.end(); ++ex)
+        ex->medial_axis(max, min/2, &polylines);
+    if (polylines.empty())
+        return coll;
+    
+    #ifdef SLIC3R_DEBUG
+    if (!curr.empty())
+        printf("  %zu gaps filled with extrusion width = %f\n", curr.size(), w);
+    #endif
+    
+    //my $flow = $layerm->flow(FLOW_ROLE_SOLID_INFILL, 0, $w);
+    Flow flow(
+        w, this->layer_height, this->solid_infill_flow.nozzle_diameter
+    );
+    
+    double mm3_per_mm = flow.mm3_per_mm();
+    
+    for (Polylines::const_iterator p = polylines.begin(); p != polylines.end(); ++p) {
+        ExtrusionPath path(erGapFill);
+        path.polyline   = *p;
+        path.mm3_per_mm = mm3_per_mm;
+        path.width      = flow.width;
+        path.height     = this->layer_height;
+        
+        if (p->is_valid() && p->first_point().coincides_with(p->last_point())) {
+            // since medial_axis() now returns only Polyline objects, detect loops here
+            ExtrusionLoop loop;
+            loop.paths.push_back(path);
+            coll.append(loop);
+        } else {
+            coll.append(path);
+        }
+    }
+    
+    return coll;
+}
+
+#ifdef SLIC3RXS
+REGISTER_CLASS(PerimeterGenerator, "Layer::PerimeterGenerator");
+#endif
+
+bool
+PerimeterGeneratorLoop::is_external() const
+{
+    return this->depth == 0;
+}
+
+bool
+PerimeterGeneratorLoop::is_internal_contour() const
+{
+    if (this->is_contour) {
+        // an internal contour is a contour containing no other contours
+        for (std::vector<PerimeterGeneratorLoop>::const_iterator loop = this->children.begin();
+            loop != this->children.end(); ++loop) {
+            if (loop->is_contour) {
+                return false;
+            }
+        }
+        return true;
+    }
+    return false;
+}
+
+}

xs/src/libslic3r/PerimeterGenerator.hpp

@@ -0,0 +1,84 @@
+#ifndef slic3r_PerimeterGenerator_hpp_
+#define slic3r_PerimeterGenerator_hpp_
+
+#include <myinit.h>
+#include <vector>
+#include "ExPolygonCollection.hpp"
+#include "Flow.hpp"
+#include "Polygon.hpp"
+#include "PrintConfig.hpp"
+#include "SurfaceCollection.hpp"
+
+namespace Slic3r {
+
+class PerimeterGeneratorLoop;
+typedef std::vector<PerimeterGeneratorLoop> PerimeterGeneratorLoops;
+
+class PerimeterGeneratorLoop {
+    public:
+    Polygon polygon;
+    bool is_contour;
+    unsigned short depth;
+    std::vector<PerimeterGeneratorLoop> children;
+    
+    PerimeterGeneratorLoop(Polygon polygon, unsigned short depth)
+        : polygon(polygon), depth(depth), is_contour(false)
+        {};
+    bool is_external() const;
+    bool is_internal_contour() const;
+};
+
+class PerimeterGenerator {
+    public:
+    SurfaceCollection* slices;
+    ExPolygonCollection* lower_slices;
+    double layer_height;
+    int layer_id;
+    Flow perimeter_flow;
+    Flow ext_perimeter_flow;
+    Flow overhang_flow;
+    Flow solid_infill_flow;
+    PrintRegionConfig* config;
+    PrintObjectConfig* object_config;
+    PrintConfig* print_config;
+    ExtrusionEntityCollection* loops;
+    ExtrusionEntityCollection* gap_fill;
+    SurfaceCollection* fill_surfaces;
+    
+    PerimeterGenerator(SurfaceCollection* slices, double layer_height, Flow flow,
+        PrintRegionConfig* config, PrintObjectConfig* object_config, 
+        PrintConfig* print_config, ExtrusionEntityCollection* loops, 
+        ExtrusionEntityCollection* gap_fill, SurfaceCollection* fill_surfaces)
+        : slices(slices), lower_slices(NULL), layer_height(layer_height),
+            perimeter_flow(flow), ext_perimeter_flow(flow), overhang_flow(flow),
+            solid_infill_flow(flow), layer_id(-1),
+            config(config), object_config(object_config), print_config(print_config),
+            loops(loops), gap_fill(gap_fill), fill_surfaces(fill_surfaces),
+            _ext_mm3_per_mm(-1), _mm3_per_mm(-1), _mm3_per_mm_overhang(-1)
+        {};
+    void process();
+    
+    private:
+    double _ext_mm3_per_mm;
+    double _mm3_per_mm;
+    double _mm3_per_mm_overhang;
+    Polygons _lower_slices_p;
+    
+    ExtrusionEntityCollection _traverse_loops(const PerimeterGeneratorLoops &loops,
+        Polylines &thin_walls) const;
+    ExtrusionEntityCollection _fill_gaps(double min, double max, double w,
+        const Polygons &gaps) const;
+};
+
+class PerimeterGeneratorGapSize {
+    public:
+    coord_t min;
+    coord_t max;
+    coord_t width;
+    PerimeterGeneratorGapSize(coord_t min, coord_t max, coord_t width)
+        : min(min), max(max), width(width) {};
+};
+
+}
+
+#endif

xs/src/libslic3r/libslic3r.h

@@ -15,6 +15,7 @@
 #define PI 3.141592653589793238
 #define LOOP_CLIPPING_LENGTH_OVER_NOZZLE_DIAMETER 0.15
 #define SMALL_PERIMETER_LENGTH (6.5 / SCALING_FACTOR) * 2 * PI
+#define INSET_OVERLAP_TOLERANCE 0.4
 #define scale_(val) (val / SCALING_FACTOR)
 #define unscale(val) (val * SCALING_FACTOR)
 #define SCALED_EPSILON scale_(EPSILON)

xs/xsp/ExtrusionEntityCollection.xsp

@@ -7,6 +7,7 @@
 
 %name{Slic3r::ExtrusionPath::Collection} class ExtrusionEntityCollection {
     %name{_new} ExtrusionEntityCollection();
+    ~ExtrusionEntityCollection();
     Clone<ExtrusionEntityCollection> clone()
         %code{% RETVAL = THIS->clone(); %};
     void reverse();
@@ -41,14 +42,6 @@
     Polygons grow();
 %{
 
-void
-ExtrusionEntityCollection::DESTROY()
-    CODE:
-        for (ExtrusionEntitiesPtr::iterator it = THIS->entities.begin(); it != THIS->entities.end(); ++it) {
-            delete *it;
-        }
-        delete THIS;
-
 SV*
 ExtrusionEntityCollection::arrayref()
     CODE:

xs/xsp/PerimeterGenerator.xsp

@@ -0,0 +1,34 @@
+%module{Slic3r::XS};
+
+%{
+#include <myinit.h>
+#include "libslic3r/PerimeterGenerator.hpp"
+%}
+
+%name{Slic3r::Layer::PerimeterGenerator} class PerimeterGenerator {
+    PerimeterGenerator(SurfaceCollection* slices, double layer_height, Flow* flow,
+        PrintRegionConfig* config, PrintObjectConfig* object_config, 
+        PrintConfig* print_config, ExtrusionEntityCollection* loops, 
+        ExtrusionEntityCollection* gap_fill, SurfaceCollection* fill_surfaces)
+        %code{% RETVAL = new PerimeterGenerator(slices, layer_height, *flow,
+            config, object_config, print_config, loops, gap_fill, fill_surfaces); %};
+    ~PerimeterGenerator();
+    
+    void set_lower_slices(ExPolygonCollection* lower_slices)
+        %code{% THIS->lower_slices = lower_slices; %};
+    void set_layer_id(int layer_id)
+        %code{% THIS->layer_id = layer_id; %};
+    void set_perimeter_flow(Flow* flow)
+        %code{% THIS->perimeter_flow = *flow; %};
+    void set_ext_perimeter_flow(Flow* flow)
+        %code{% THIS->ext_perimeter_flow = *flow; %};
+    void set_overhang_flow(Flow* flow)
+        %code{% THIS->overhang_flow = *flow; %};
+    void set_solid_infill_flow(Flow* flow)
+        %code{% THIS->solid_infill_flow = *flow; %};
+    
+    Ref<PrintRegionConfig> config()
+        %code{% RETVAL = THIS->config; %};
+    
+    void process();
+};

xs/xsp/my.map

@@ -198,6 +198,10 @@ BridgeDetector*            O_OBJECT_SLIC3R
 Ref<BridgeDetector>        O_OBJECT_SLIC3R_T
 Clone<BridgeDetector>      O_OBJECT_SLIC3R_T
 
+PerimeterGenerator*         O_OBJECT_SLIC3R
+Ref<PerimeterGenerator>     O_OBJECT_SLIC3R_T
+Clone<PerimeterGenerator>   O_OBJECT_SLIC3R_T
+
 GLVertexArray*             O_OBJECT_SLIC3R
 
 Axis                  T_UV

xs/xsp/typemap.xspt

@@ -94,6 +94,12 @@
 %typemap{BridgeDetector*};
 %typemap{Ref<BridgeDetector>}{simple};
 %typemap{Clone<BridgeDetector>}{simple};
+%typemap{SurfaceCollection*};
+%typemap{Ref<SurfaceCollection>}{simple};
+%typemap{Clone<SurfaceCollection>}{simple};
+%typemap{PerimeterGenerator*};
+%typemap{Ref<PerimeterGenerator>}{simple};
+%typemap{Clone<PerimeterGenerator>}{simple};
 
 %typemap{Surface*};
 %typemap{Ref<Surface>}{simple};
@@ -153,7 +159,6 @@
 %typemap{Polygons*};
 %typemap{TriangleMesh*};
 %typemap{TriangleMeshPtrs};
-%typemap{Ref<SurfaceCollection>}{simple};
 %typemap{Extruder*};
 %typemap{Ref<Extruder>}{simple};
 %typemap{Clone<Extruder>}{simple};