From ff5044c0317989cee4553f65226d110db1751986 Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Mon, 5 Sep 2011 20:00:59 +0200
Subject: [PATCH] Implemented skirt

---
 README.markdown         |  8 +++-----
 lib/Slic3r.pm           |  3 +++
 lib/Slic3r/Layer.pm     |  7 +++++++
 lib/Slic3r/Perimeter.pm | 17 +++++++++++++++++
 lib/Slic3r/Print.pm     |  3 +++
 slic3r.pl               |  5 +++++
 6 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/README.markdown b/README.markdown
index 35a54647..48d93ae7 100644
--- a/README.markdown
+++ b/README.markdown
@@ -28,16 +28,16 @@ Also, http://xkcd.com/224/
 
 ## What's its current status?
 
-Slic3r is able to:
+Slic3r current features are:
 
 * read binary and ASCII STL files;
 * generate multiple perimeters (skins);
 * generate rectilinear fill (100% solid for external surfaces or with customizable less density for inner surfaces);
 * retraction;
+* skirt;
 * use relative or absolute extrusion commands;
 * center print around bed center point;
-* use different speed for bottom layer;
-* output relevant GCODE.
+* use different speed for bottom layer.
 
 Roadmap includes the following goals:
 
@@ -46,8 +46,6 @@ Roadmap includes the following goals:
 * option for filling multiple solid layers near external surfaces;
 * support material for internal perimeters;
 * ability to infill in the direction of bridges;
-* extra perimeters on alternate layers;
-* skirt;
 * cool;
 * nice packaging for cross-platform deployment.
 
diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index b876c2a5..63f7d8d3 100644
--- a/lib/Slic3r.pm
+++ b/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
diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index a81a250a..6a7fdcb6 100644
--- a/lib/Slic3r/Layer.pm
+++ b/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' => (
diff --git a/lib/Slic3r/Perimeter.pm b/lib/Slic3r/Perimeter.pm
index 6879864a..88d273a9 100644
--- a/lib/Slic3r/Perimeter.pm
+++ b/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 {
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 56583566..0a23aa32 100644
--- a/lib/Slic3r/Print.pm
+++ b/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 };
         
diff --git a/slic3r.pl b/slic3r.pl
index ecbb3902..388784ba 100644
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -29,6 +29,8 @@ GetOptions(
     'temperature=i'         => \$Slic3r::temperature,
     'print-feed-rate=i'     => \$Slic3r::print_feed_rate,
     'travel-feed-rate=i'    => \$Slic3r::travel_feed_rate,
+    'skirts=i'              => \$Slic3r::skirts,
+    'skirt-distance=i'              => \$Slic3r::skirt_distance,
     'bottom-layer-speed-ratio=f'    => \$Slic3r::bottom_layer_speed_ratio,
     'use-relative-e-distances'      => \$Slic3r::use_relative_e_distances,
     'print-center=s'        => \$Slic3r::print_center,
@@ -120,6 +122,9 @@ Usage: slic3r.pl [ OPTIONS ] file.stl
     --retract-restart-extra
                         Additional amount of filament in mm to push after compensating
                         retraction (default: $Slic3r::retract_restart_extra)
+    --skirts            Number of skirts to draw (default: $Slic3r::skirts)
+    --skirt-distance    Distance in mm between innermost skirt and object 
+                        (default: $Slic3r::skirt_distance)
     --use-relative-e-distances
                         Use relative distances for extrusion in GCODE output
     --print-center      Coordinates of the point to center the print around