From 36e1ea0caa653a2dbd286b0b2ef891ee3331276a Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Mon, 21 Nov 2011 16:35:10 +0100
Subject: [PATCH] Make sure bridges don't overlap. #58

---
 lib/Slic3r/Layer.pm | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index 5d5b1f821..ff59de281 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -297,6 +297,7 @@ sub make_surfaces {
         
         $self->cleanup_lines;
         eval { $detect->(); };
+        warn $@ if $@;
         
         if (@discarded_lines) {
             print "  Warning: even slow detection algorithm throwed errors. Review the output before printing.\n";
@@ -441,6 +442,36 @@ sub process_bridges {
             ), @$intersection;
         }
     }
+    
+    # now we need to merge bridges to avoid overlapping
+    {
+        # build a list of unique bridge types
+        my $unique_type = sub { $_[0]->surface_type . "_" . ($_[0]->bridge_angle || '') };
+        my @unique_types = ();
+        foreach my $bridge (@{$self->bridges}) {
+            push @unique_types, $unique_type->($bridge);
+        }
+        
+        # merge bridges of the same type, removing any of the bridges already merged;
+        # the order of @unique_types determines the priority between bridges having 
+        # different surface_type or bridge_angle
+        my @bridges = ();
+        foreach my $type (@unique_types) {
+            my @surfaces = grep { $unique_type->($_) eq $type } @{$self->bridges};
+            my $union = union_ex([ map $_->p, @surfaces ]);
+            my $diff = diff_ex(
+                [ map @$_, @$union ],
+                [ map $_->p, @bridges ],
+            );
+            
+            push @bridges, map Slic3r::Surface::Bridge->cast_from_expolygon($_,
+                surface_type => $surfaces[0]->surface_type,
+                bridge_angle => $surfaces[0]->bridge_angle,
+            ), @$union;
+        }
+        
+        @{$self->bridges} = @bridges;
+    }
 }
 
 # generates a set of surfaces that will be used to make perimeters