Implemented skirt

lib/Slic3r.pm

@@ -38,6 +38,9 @@ our $retract_length         = 2;    # mm
 our $retract_restart_extra  = 0;    # mm
 our $retract_speed          = 40;   # mm/sec
 
+our $skirts             = 3;
+our $skirt_distance     = 6;    # mm
+
 our $use_relative_e_distances = 0;
 
 our $print_center       = [100,100];  # object will be centered around this point

lib/Slic3r/Layer.pm

@@ -46,6 +46,13 @@ has 'perimeters' => (
     default => sub { [] },
 );
 
+# ordered collection of extrusion paths to build skirt loops
+has 'skirts' => (
+    is      => 'rw',
+    isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
+    default => sub { [] },
+);
+
 # collection of surfaces generated by offsetting the innermost perimeter(s)
 # they represent boundaries of areas to fill
 has 'fill_surfaces' => (

lib/Slic3r/Perimeter.pm

@@ -73,6 +73,23 @@ sub make_perimeter {
         }
         push @{ $layer->perimeters }, Slic3r::ExtrusionPath->new_from_points(reverse @path_points);
     }
+    
+    # generate skirt on bottom layer
+    if ($layer->id == 0 && $Slic3r::skirts > 0) {
+        # find out convex hull
+        my $points = [ map { @{ $_->mgp_polygon->polygons->[0] } } @{ $layer->surfaces } ];
+        my $convex_hull = $self->_mgp_from_points_ref($points)->convexhull2;
+        my $convex_hull_polygon = $self->_mgp_from_points_ref($convex_hull);
+        
+        # draw outlines from outside to inside
+        for (my $i = $Slic3r::skirts - 1; $i >= 0; $i--) {
+            my $outline = $convex_hull_polygon->offset_polygon(
+                - ($Slic3r::skirt_distance + ($Slic3r::flow_width * $i)) / $Slic3r::resolution
+            );
+            push @{$outline->[0]}, $outline->[0][0]; # repeat first point as last to complete the loop
+            push @{ $layer->skirts }, Slic3r::ExtrusionPath->new_from_points(@{$outline->[0]});
+        }
+    }
 }
 
 sub offset_polygon {

lib/Slic3r/Print.pm

@@ -185,6 +185,9 @@ sub export_gcode {
         printf $fh "G1 Z%.${dec}f F%.${dec}f ; move to next layer\n", 
             $z, $travel_feed_rate;
         
+        # extrude skirts
+        $Extrude->($_, 'skirt') for @{ $layer->skirts };
+        
         # extrude perimeters
         $Extrude->($_, 'perimeter') for @{ $layer->perimeters };