From c2301c5796713ee50025c565a0b5a44f69d9f97d Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Mon, 29 Apr 2013 15:53:15 +0200
Subject: [PATCH] Don't extend solid layers when fill density is 0

---
 lib/Slic3r/Layer/Region.pm | 10 ++++++++--
 lib/Slic3r/Print/Object.pm |  7 ++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/lib/Slic3r/Layer/Region.pm b/lib/Slic3r/Layer/Region.pm
index bdabbd09c..551c3ac63 100644
--- a/lib/Slic3r/Layer/Region.pm
+++ b/lib/Slic3r/Layer/Region.pm
@@ -473,17 +473,23 @@ sub process_external_surfaces {
         my @top     = grep $_->surface_type == S_TYPE_TOP, @{$self->fill_surfaces};
         my @bottom  = grep $_->surface_type == S_TYPE_BOTTOM, @{$self->fill_surfaces};
         
+        # if we're slicing with no infill, we can't extend external surfaces
+        # over non-existent infill
+        my @fill_boundaries = $Slic3r::Config->fill_density > 0
+            ? @{$self->fill_surfaces}
+            : grep $_->surface_type != S_TYPE_INTERNAL, @{$self->fill_surfaces};
+        
         # offset them and intersect the results with the actual fill boundaries
         my $margin = scale 3;  # TODO: ensure this is greater than the total thickness of the perimeters
         @top = @{intersection_ex(
             [ Slic3r::Geometry::Clipper::offset([ map $_->p, @top ], +$margin) ],
-            [ map $_->p, @{$self->fill_surfaces} ],
+            [ map $_->p, @fill_boundaries ],
             undef,
             1,  # to ensure adjacent expolygons are unified
         )};
         @bottom = @{intersection_ex(
             [ Slic3r::Geometry::Clipper::offset([ map $_->p, @bottom ], +$margin) ],
-            [ map $_->p, @{$self->fill_surfaces} ],
+            [ map $_->p, @fill_boundaries ],
             undef,
             1,  # to ensure adjacent expolygons are unified
         )};
diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index d4052fcc9..7b21db874 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -637,10 +637,15 @@ sub discover_horizontal_shells {
                         # if some parts are going to collapse, let's grow them and add the extra area to the neighbor layer
                         # as well as to our original surfaces so that we support this additional area in the next shell too
                         if (@$too_narrow) {
+                            # consider the actual fill area
+                            my @fill_boundaries = $Slic3r::Config->fill_density > 0
+                                ? @neighbor_fill_surfaces
+                                : grep $_->surface_type != S_TYPE_INTERNAL, @neighbor_fill_surfaces;
+                            
                             # make sure our grown surfaces don't exceed the fill area
                             my @grown = map @$_, @{intersection_ex(
                                 [ offset([ map @$_, @$too_narrow ], +$margin) ],
-                                [ map $_->p, @neighbor_fill_surfaces ],
+                                [ map $_->p, @fill_boundaries ],
                             )};
                             $new_internal_solid = union_ex([ @grown, (map @$_, @$new_internal_solid) ]);
                             $solid = union_ex([ @grown, (map @$_, @$solid) ]);