Organize perimeters with a nearest point search to avoid unnecessary …

…travel moves. #21

lib/Slic3r/ExtrusionPath/Collection.pm

@@ -29,7 +29,9 @@ sub shortest_path {
     my $start_at;
     CYCLE: while (@{$self->paths}) {
         # find nearest point
-        $start_at = Slic3r::Point->new(Slic3r::Geometry::nearest_point($start_near, [ $self->endpoints ]));
+        $start_at = $start_near
+            ? Slic3r::Point->new(Slic3r::Geometry::nearest_point($start_near, [ $self->endpoints ]))
+            : $self->endpoints->[0];
 
         # loop through paths to find the one that starts or ends at the point found
         PATH: for (my $i = 0; $i <= $#{$self->paths}; $i++) {

lib/Slic3r/Geometry.pm

@@ -17,6 +17,7 @@ our @EXPORT_OK = qw(
     clip_segment_complex_polygon longest_segment angle3points
     polyline_remove_parallel_continuous_edges polyline_remove_acute_vertices
     polygon_remove_acute_vertices polygon_remove_parallel_continuous_edges
+    shortest_path
 );
 
 use Slic3r::Geometry::DouglasPeucker qw(Douglas_Peucker);
@@ -611,4 +612,29 @@ sub polygon_remove_acute_vertices {
     return polyline_remove_acute_vertices($points, 1);
 }
 
+# accepts an arrayref; each item should be an arrayref whose first
+# item is the point to be used for the shortest path, and the second
+# one is the value to be returned in output (if the second item
+# is not provided, the point will be returned)
+sub shortest_path {
+    my ($items, $start_near) = @_;
+
+    my %values = map +($_->[0] => $_->[1] || $_->[0]), @$items;
+    my @points = map $_->[0], @$items;
+
+    my $result = [];
+    my $last_point;
+    if (!$start_near) {
+        $start_near = shift @points;
+        push @$result, $values{$start_near} if $start_near;
+    }
+    while (@points) {
+        $start_near = nearest_point($start_near, [@points]);
+        @points = grep $_ ne $start_near, @points;
+        push @$result, $values{$start_near};
+    }
+
+    return $result;
+}
+
 1;

lib/Slic3r/Perimeter.pm

@@ -3,6 +3,7 @@ use Moo;
 
 use Math::Clipper ':all';
 use Math::ConvexHull 1.0.4 qw(convex_hull);
+use Slic3r::Geometry qw(shortest_path);
 use XXX;
 
 use constant X => 0;
@@ -31,6 +32,11 @@ sub make_perimeter {
     # )
     my @perimeters = ();  # one item per depth; each item
 
+    # organize $layer->perimeter_surfaces using a shortest path search
+    @{ $layer->perimeter_surfaces } = @{shortest_path([
+        map [ $_->contour->points->[0], $_ ], @{ $layer->perimeter_surfaces },
+    ])};
+
     foreach my $surface (@{ $layer->perimeter_surfaces }) {
         # the outer loop must be offsetted by half extrusion width inwards
         my @last_offsets = ($surface->expolygon);