Merge pull request #471 from eyal0/cutter_sort

Sort outline cuts from shortest to longest instead of using TSP

surface_vectorial.cpp

@@ -251,10 +251,20 @@ multi_linestring_type_fp Surface_vectorial::post_process_toolpath(
   for (const auto& ls_and_allow_reversal : toolpath1) {
     combined_toolpath.push_back(ls_and_allow_reversal.first);
   }
-  if (tsp_2opt) {
-    tsp_solver::tsp_2opt(combined_toolpath, point_type_fp(0, 0));
+  if (dynamic_pointer_cast<Isolator>(mill) != nullptr) {
+    if (tsp_2opt) {
+      tsp_solver::tsp_2opt(combined_toolpath, point_type_fp(0, 0));
+    } else {
+      tsp_solver::nearest_neighbour(combined_toolpath, point_type_fp(0, 0));
+    }
   } else {
-    tsp_solver::nearest_neighbour(combined_toolpath, point_type_fp(0, 0));
+    // It's a cutter so do the cuts from shortest to longest.  This
+    // makes it very likely that the inside cuts will happen before
+    // the perimeter cut, which is best for stability of the PCB.
+    std::sort(combined_toolpath.begin(), combined_toolpath.end(),
+              [](const linestring_type_fp& lhs, const linestring_type_fp rhs) {
+                return bg::length(lhs) < bg::length(rhs);
+              });
   }
 
   if (mill->optimise) {

testing/gerbv_example/edge-cuts-inside-cuts/expected/outline.ngc

@@ -22,17 +22,6 @@ G04 P1.00000 (Wait for spindle to get up to speed)
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G00 Z0.08000 ( retract )
 
-G00 X4.35000 Y-4.35000 ( rapid move to begin. )
-G01 Z-0.00512 F50.00000 ( plunge. )
-G04 P0 ( dwell for no time -- G64 should not smooth over this point )
-G01 F100.00000
-G01 X4.35000 Y-3.80000
-G01 X5.05000 Y-3.80000
-G01 X5.05000 Y-4.35000
-G01 X4.35000 Y-4.35000
-G04 P0 ( dwell for no time -- G64 should not smooth over this point )
-G00 Z0.08000 ( retract )
-
 G00 X4.55000 Y-4.25000 ( rapid move to begin. )
 G01 Z-0.00512 F50.00000 ( plunge. )
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
@@ -85,6 +74,17 @@ G01 X4.61910 Y-3.89122
 G01 X4.60865 Y-3.90933
 G01 X4.60219 Y-3.92921
 G01 X4.60000 Y-3.95000
+G04 P0 ( dwell for no time -- G64 should not smooth over this point )
+G00 Z0.08000 ( retract )
+
+G00 X4.35000 Y-4.35000 ( rapid move to begin. )
+G01 Z-0.00512 F50.00000 ( plunge. )
+G04 P0 ( dwell for no time -- G64 should not smooth over this point )
+G01 F100.00000
+G01 X4.35000 Y-3.80000
+G01 X5.05000 Y-3.80000
+G01 X5.05000 Y-4.35000
+G01 X4.35000 Y-4.35000
 
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G00 Z1.000000 ( retract )