Promising approach to medial axis pruning

xs/xsp/Line.xsp

@@ -21,6 +21,8 @@
     void scale(double factor);
     void translate(double x, double y);
     double length();
+    double atan2_();
+    double direction();
     Point* midpoint()
          %code{% const char* CLASS = "Slic3r::Point"; RETVAL = THIS->midpoint(); %};
     Point* point_at(double distance)