Fixed regression due to ExPolygonCollection to ExPolygons refactoring.

Fixed crashes in BridgeDetector due to unexpected implicit conversion
to a const temporary.

src/libslic3r/BridgeDetector.cpp

@@ -6,9 +6,9 @@
 namespace Slic3r {
 
 BridgeDetector::BridgeDetector(
-    ExPolygon                   _expolygon,
+    ExPolygon         _expolygon,
-    const ExPolygonCollection  &_lower_slices, 
+    const ExPolygons &_lower_slices, 
-    coord_t                     _spacing) :
+    coord_t           _spacing) :
     // The original infill polygon, not inflated.
     expolygons(expolygons_owned),
     // All surfaces of the object supporting this region.
@@ -20,9 +20,9 @@ BridgeDetector::BridgeDetector(
 }
 
 BridgeDetector::BridgeDetector(
-    const ExPolygons           &_expolygons,
+    const ExPolygons  &_expolygons,
-    const ExPolygonCollection  &_lower_slices,
+    const ExPolygons  &_lower_slices,
-    coord_t                     _spacing) : 
+    coord_t            _spacing) : 
     // The original infill polygon, not inflated.
     expolygons(_expolygons),
     // All surfaces of the object supporting this region.
@@ -46,7 +46,11 @@ void BridgeDetector::initialize()
     // Detect what edges lie on lower slices by turning bridge contour and holes
     // into polylines and then clipping them with each lower slice's contour.
     // Currently _edges are only used to set a candidate direction of the bridge (see bridge_direction_candidates()).
-    this->_edges = intersection_pl(to_polylines(grown), this->lower_slices.contours());
+	Polygons contours;
+	contours.reserve(this->lower_slices.size());
+	for (const ExPolygon &expoly : this->lower_slices)
+		contours.push_back(expoly.contour);
+    this->_edges = intersection_pl(to_polylines(grown), contours);
     
     #ifdef SLIC3R_DEBUG
     printf("  bridge has " PRINTF_ZU " support(s)\n", this->_edges.size());
@@ -54,7 +58,7 @@ void BridgeDetector::initialize()
     
     // detect anchors as intersection between our bridge expolygon and the lower slices
     // safety offset required to avoid Clipper from detecting empty intersection while Boost actually found some edges
-    this->_anchor_regions = intersection_ex(grown, to_polygons(this->lower_slices.expolygons), true);
+    this->_anchor_regions = intersection_ex(grown, to_polygons(this->lower_slices), true);
     
     /*
     if (0) {
@@ -271,7 +275,7 @@ BridgeDetector::unsupported_edges(double angle, Polylines* unsupported) const
     if (angle == -1) angle = this->angle;
     if (angle == -1) return;
 
-    Polygons grown_lower = offset(this->lower_slices.expolygons, float(this->spacing));
+    Polygons grown_lower = offset(this->lower_slices, float(this->spacing));
 
     for (ExPolygons::const_iterator it_expoly = this->expolygons.begin(); it_expoly != this->expolygons.end(); ++ it_expoly) {    
         // get unsupported bridge edges (both contour and holes)

src/libslic3r/BridgeDetector.hpp

@@ -3,7 +3,6 @@
 
 #include "libslic3r.h"
 #include "ExPolygon.hpp"
-#include "ExPolygonCollection.hpp"
 #include <string>
 
 namespace Slic3r {
@@ -21,7 +20,7 @@ public:
     // In case the caller gaves us the input polygons by a value, make a copy.
     ExPolygons                   expolygons_owned;
     // Lower slices, all regions.
-    const ExPolygonCollection   &lower_slices;
+    const ExPolygons   			&lower_slices;
     // Scaled extrusion width of the infill.
     coord_t                      spacing;
     // Angle resolution for the brute force search of the best bridging angle.
@@ -29,8 +28,8 @@ public:
     // The final optimal angle.
     double                       angle;
     
-    BridgeDetector(ExPolygon _expolygon, const ExPolygonCollection &_lower_slices, coord_t _extrusion_width);
+    BridgeDetector(ExPolygon _expolygon, const ExPolygons &_lower_slices, coord_t _extrusion_width);
-    BridgeDetector(const ExPolygons &_expolygons, const ExPolygonCollection &_lower_slices, coord_t _extrusion_width);
+    BridgeDetector(const ExPolygons &_expolygons, const ExPolygons &_lower_slices, coord_t _extrusion_width);
     // If bridge_direction_override != 0, then the angle is used instead of auto-detect.
     bool detect_angle(double bridge_direction_override = 0.);
     Polygons coverage(double angle = -1) const;

src/libslic3r/ExPolygonCollection.cpp

@@ -11,7 +11,7 @@ ExPolygonCollection::ExPolygonCollection(const ExPolygon &expolygon)
 ExPolygonCollection::operator Points() const
 {
     Points points;
-    Polygons pp = *this;
+    Polygons pp = (Polygons)*this;
     for (Polygons::const_iterator poly = pp.begin(); poly != pp.end(); ++poly) {
         for (Points::const_iterator point = poly->points.begin(); point != poly->points.end(); ++point)
             points.push_back(*point);

src/libslic3r/ExPolygonCollection.hpp

@@ -17,11 +17,11 @@ public:
     ExPolygons expolygons;
     
     ExPolygonCollection() {}
-    ExPolygonCollection(const ExPolygon &expolygon);
+    explicit ExPolygonCollection(const ExPolygon &expolygon);
-    ExPolygonCollection(const ExPolygons &expolygons) : expolygons(expolygons) {}
+    explicit ExPolygonCollection(const ExPolygons &expolygons) : expolygons(expolygons) {}
-    operator Points() const;
+    explicit operator Points() const;
-    operator Polygons() const;
+    explicit operator Polygons() const;
-    operator ExPolygons&();
+    explicit operator ExPolygons&();
     void scale(double factor);
     void translate(double x, double y);
     void rotate(double angle, const Point &center);

src/libslic3r/ExtrusionEntity.cpp

@@ -14,12 +14,12 @@ namespace Slic3r {
     
 void ExtrusionPath::intersect_expolygons(const ExPolygonCollection &collection, ExtrusionEntityCollection* retval) const
 {
-    this->_inflate_collection(intersection_pl(this->polyline, collection), retval);
+    this->_inflate_collection(intersection_pl(this->polyline, (Polygons)collection), retval);
 }
 
 void ExtrusionPath::subtract_expolygons(const ExPolygonCollection &collection, ExtrusionEntityCollection* retval) const
 {
-    this->_inflate_collection(diff_pl(this->polyline, collection), retval);
+    this->_inflate_collection(diff_pl(this->polyline, (Polygons)collection), retval);
 }
 
 void ExtrusionPath::clip_end(double distance)

src/libslic3r/MotionPlanner.cpp

@@ -136,11 +136,11 @@ Polyline MotionPlanner::shortest_path(const Point &from, const Point &to)
             if (! grown_env.contains(from)) {
                 // delete second point while the line connecting first to third crosses the
                 // boundaries as many times as the current first to second
-                while (polyline.points.size() > 2 && intersection_ln(Line(from, polyline.points[2]), grown_env).size() == 1)
+                while (polyline.points.size() > 2 && intersection_ln(Line(from, polyline.points[2]), (Polygons)grown_env).size() == 1)
                     polyline.points.erase(polyline.points.begin() + 1);
             }
             if (! grown_env.contains(to))
-                while (polyline.points.size() > 2 && intersection_ln(Line(*(polyline.points.end() - 3), to), grown_env).size() == 1)
+                while (polyline.points.size() > 2 && intersection_ln(Line(*(polyline.points.end() - 3), to), (Polygons)grown_env).size() == 1)
                     polyline.points.erase(polyline.points.end() - 2);
         }
 

xs/xsp/BridgeDetector.xsp

@@ -25,7 +25,7 @@ BridgeDetector::new(expolygon, lower_slices, extrusion_width)
     ExPolygonCollection*    lower_slices;
     int                     extrusion_width;
     CODE:
-        RETVAL = new BridgeDetector(*expolygon, *lower_slices, extrusion_width);
+        RETVAL = new BridgeDetector(*expolygon, lower_slices->expolygons, extrusion_width);
     OUTPUT:
         RETVAL
 
@@ -35,7 +35,7 @@ BridgeDetector::new_expolygons(expolygons, lower_slices, extrusion_width)
     ExPolygonCollection*    lower_slices;
     int                     extrusion_width;
     CODE:
-        RETVAL = new BridgeDetector(expolygons->expolygons, *lower_slices, extrusion_width);
+        RETVAL = new BridgeDetector(expolygons->expolygons, lower_slices->expolygons, extrusion_width);
     OUTPUT:
         RETVAL
 

xs/xsp/ExPolygonCollection.xsp

@@ -25,7 +25,7 @@
         %code{% RETVAL = THIS->contains(*polyline); %};
     void simplify(double tolerance);
     Polygons polygons()
-        %code{% RETVAL = *THIS; %};
+        %code{% RETVAL = (Polygons)*THIS; %};
     Clone<Polygon> convex_hull();
 %{