Speed up of organic support smoothing & collision detection.

src/libslic3r/TreeModelVolumes.hpp

@@ -237,6 +237,11 @@ public:
      */
     const Polygons& getCollision(const coord_t radius, LayerIndex layer_idx, bool min_xy_dist) const;
 
+    // Get a collision area at a given layer for a radius that is a lower or equial to the key radius.
+    // It is expected that the collision area is precalculated for a given layer at least for the radius zero.
+    // Used for pushing tree supports away from object during the final Organic optimization step.
+    std::optional<std::pair<coord_t, std::reference_wrapper<const Polygons>>> get_collision_lower_bound_area(LayerIndex layer_id, coord_t max_radius) const;
+
     /*!
      * \brief Provides the areas that have to be avoided by the tree's branches
      * in order to reach the build plate.