WIP: Moved sources int src/, separated most of the source code from Perl.

The XS was left only for the unit / integration tests, and it links
libslic3r only. No wxWidgets are allowed to be used from Perl starting
from now.

src/libslic3r/BridgeDetector.hpp

@@ -0,0 +1,69 @@
+#ifndef slic3r_BridgeDetector_hpp_
+#define slic3r_BridgeDetector_hpp_
+
+#include "libslic3r.h"
+#include "ExPolygon.hpp"
+#include "ExPolygonCollection.hpp"
+#include <string>
+
+namespace Slic3r {
+
+// The bridge detector optimizes a direction of bridges over a region or a set of regions.
+// A bridge direction is considered optimal, if the length of the lines strang over the region is maximal.
+// This is optimal if the bridge is supported in a single direction only, but
+// it may not likely be optimal, if the bridge region is supported from all sides. Then an optimal 
+// solution would find a direction with shortest bridges.
+// The bridge orientation is measured CCW from the X axis.
+class BridgeDetector {
+public:
+    // The non-grown holes.
+    const ExPolygons            &expolygons;
+    // 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;
+    // Scaled extrusion width of the infill.
+    coord_t                      spacing;
+    // Angle resolution for the brute force search of the best bridging angle.
+    double                       resolution;
+    // The final optimal angle.
+    double                       angle;
+    
+    BridgeDetector(ExPolygon _expolygon, const ExPolygonCollection &_lower_slices, coord_t _extrusion_width);
+    BridgeDetector(const ExPolygons &_expolygons, const ExPolygonCollection &_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;
+    void unsupported_edges(double angle, Polylines* unsupported) const;
+    Polylines unsupported_edges(double angle = -1) const;
+    
+private:
+    // Suppress warning "assignment operator could not be generated"
+    BridgeDetector& operator=(const BridgeDetector &);
+
+    void initialize();
+
+    struct BridgeDirection {
+        BridgeDirection(double a = -1.) : angle(a), coverage(0.), max_length(0.) {}
+        // the best direction is the one causing most lines to be bridged (thus most coverage)
+        bool operator<(const BridgeDirection &other) const {
+            // Initial sort by coverage only - comparator must obey strict weak ordering
+            return this->coverage > other.coverage;
+        };
+        double angle;
+        double coverage;
+        double max_length;
+    };
+
+    // Get possible briging direction candidates.
+    std::vector<double> bridge_direction_candidates() const;
+
+    // Open lines representing the supporting edges.
+    Polylines _edges;
+    // Closed polygons representing the supporting areas.
+    ExPolygons _anchor_regions;
+};
+
+}
+
+#endif