From 4cdd0f6fd0452173fac55895c8f01ec3896cf97b Mon Sep 17 00:00:00 2001
From: Alessandro Ranellucci <aar@cpan.org>
Date: Sun, 27 Nov 2011 10:12:44 +0100
Subject: [PATCH] Bugfix: sparse and wrong infill was generated for objects
 with null fill density. Also fixed a division by zero.

---
 lib/Slic3r/Extruder.pm |  2 +-
 lib/Slic3r/Layer.pm    | 27 +++++++++++++++++++--------
 lib/Slic3r/Print.pm    |  7 +++++++
 lib/Slic3r/Skein.pm    |  6 +++---
 4 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/lib/Slic3r/Extruder.pm b/lib/Slic3r/Extruder.pm
index cb24fe973..f873ad4e3 100644
--- a/lib/Slic3r/Extruder.pm
+++ b/lib/Slic3r/Extruder.pm
@@ -89,7 +89,7 @@ sub extrude {
         my $distance_from_last_pos = $self->last_pos->distance_to($path->points->[0]) * $Slic3r::resolution;
         my $distance_threshold = $Slic3r::retract_before_travel;
         $distance_threshold = 2 * $Slic3r::flow_width / $Slic3r::fill_density * sqrt(2)
-            if $description =~ /fill/;
+            if $Slic3r::fill_density > 0 && $description =~ /fill/;
     
         if ($distance_from_last_pos >= $distance_threshold) {
             $gcode .= $self->retract(travel_to => $path->points->[0]);
diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index a4ad47382..187e6ffbe 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -311,17 +311,28 @@ sub remove_small_surfaces {
     my $self = shift;
     my @good_surfaces = ();
     
-    my $surface_count = scalar @{$self->surfaces};
-    foreach my $surface (@{$self->surfaces}) {
-        next if !$surface->contour->is_printable;
-        @{$surface->holes} = grep $_->is_printable, @{$surface->holes};
-        push @good_surfaces, $surface;
+    my $distance = ($Slic3r::flow_width / 2 / $Slic3r::resolution);
+    
+    my @surfaces = @{$self->surfaces};
+    @{$self->surfaces} = ();
+    foreach my $surface (@surfaces) {
+        # offset inwards
+        my @offsets = $surface->expolygon->offset_ex(-$distance);
+        
+        # offset the results outwards again and merge the results
+        @offsets = map $_->offset_ex($distance), @offsets;
+        @offsets = @{ union_ex([ map @$_, @offsets ]) };
+        
+        # the difference between $surface->expolygon and @offsets 
+        # is what we can't print since it's too small
+        
+        push @{$self->surfaces}, map Slic3r::Surface->cast_from_expolygon($_,
+            surface_type => $surface->surface_type), @offsets;
     }
     
-    @{$self->surfaces} = @good_surfaces;
     Slic3r::debugf "removed %d small surfaces at layer %d\n",
-        ($surface_count - @good_surfaces), $self->id 
-        if @good_surfaces != $surface_count;
+        (@surfaces - @{$self->surfaces}), $self->id 
+        if @{$self->surfaces} != @surfaces;
 }
 
 sub remove_small_perimeters {
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 1a13c4ea6..7835d746c 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -171,6 +171,13 @@ sub detect_surfaces_type {
         Slic3r::debugf "  layer %d has %d bottom, %d top and %d internal surfaces\n",
             $layer->id, scalar(@bottom), scalar(@top), scalar(@internal);
     }
+    
+    # remove internal surfaces if no infill is requested
+    if ($Slic3r::fill_density == 0) {
+        foreach my $layer (@{$self->layers}) {
+            @{$layer->surfaces} = grep $_->surface_type ne 'internal', @{$layer->surfaces};
+        }
+    }
 }
 
 sub discover_horizontal_shells {
diff --git a/lib/Slic3r/Skein.pm b/lib/Slic3r/Skein.pm
index 2a93d559c..100dac930 100644
--- a/lib/Slic3r/Skein.pm
+++ b/lib/Slic3r/Skein.pm
@@ -35,9 +35,9 @@ sub go {
         $perimeter_maker->make_perimeter($_) for @{$print->layers};
     }
     
-    # this will prepare surfaces for perimeters by merging all
-    # surfaces in each layer; it will also clip $layer->surfaces 
-    # to the infill boundaries and split them in top/bottom/internal surfaces
+    # this will clip $layer->surfaces to the infill boundaries 
+    # and split them in top/bottom/internal surfaces;
+    # if fill density is null, it will delete all internal surfaces
     $self->status_cb->(30, "Detecting solid surfaces...");
     $print->detect_surfaces_type;