ENH: reorder print area to reduce travel time

Signed-off-by: qing.zhang <qing.zhang@bambulab.com>
Change-Id: I8fd5c505a42ae850d91c061d4df08257fb03c8c8

src/libslic3r/PerimeterGenerator.cpp

@@ -835,7 +835,13 @@ void PerimeterGenerator::process_classic()
 
     // BBS: don't simplify too much which influence arc fitting when export gcode if arc_fitting is enabled
     double surface_simplify_resolution = (print_config->enable_arc_fitting && this->config->fuzzy_skin == FuzzySkinType::None) ? 0.2 * m_scaled_resolution : m_scaled_resolution;
-    for (const Surface &surface : this->slices->surfaces) {
+    //BBS: reorder the surface to reduce the travel time
+    ExPolygons surface_exp;
+    for (const Surface &surface : this->slices->surfaces)
+        surface_exp.push_back(surface.expolygon);
+    std::vector<size_t> surface_order = chain_expolygons(surface_exp);
+    for (size_t order_idx = 0; order_idx < surface_order.size(); order_idx++) {
+        const Surface &surface = this->slices->surfaces[surface_order[order_idx]];
         // detect how many perimeters must be generated for this island
         int        loop_number = this->config->wall_loops + surface.extra_perimeters - 1;  // 0-indexed loops
         //BBS: set the topmost and bottom most layer to be one wall

src/libslic3r/ShortestPath.cpp

@@ -1057,6 +1057,16 @@ void chain_and_reorder_extrusion_paths(std::vector<ExtrusionPath> &extrusion_pat
 	reorder_extrusion_paths(extrusion_paths, chain_extrusion_paths(extrusion_paths, start_near));
 }
 
+std::vector<size_t> chain_expolygons(const ExPolygons &input_exploy) {
+	Points points;
+	for (const ExPolygon &exploy : input_exploy) {
+		BoundingBox bbox;
+		bbox = get_extents(exploy);
+		points.push_back(bbox.center());
+	}
+	return chain_points(points);
+}
+
 std::vector<size_t> chain_points(const Points &points, Point *start_near)
 {
 	auto segment_end_point = [&points](size_t idx, bool /* first_point */) -> const Point& { return points[idx]; };

src/libslic3r/ShortestPath.hpp

@@ -13,6 +13,7 @@ namespace ClipperLib { class PolyNode; }
 namespace Slic3r {
 
 std::vector<size_t> 				 chain_points(const Points &points, Point *start_near = nullptr);
+std::vector<size_t> 				 chain_expolygons(const ExPolygons &input_exploy);
 
 std::vector<std::pair<size_t, bool>> chain_extrusion_entities(std::vector<ExtrusionEntity*> &entities, const Point *start_near = nullptr);
 void                                 reorder_extrusion_entities(std::vector<ExtrusionEntity*> &entities, const std::vector<std::pair<size_t, bool>> &chain);