New option to define the overhang threshold angle for support material generation

README.markdown

@@ -164,6 +164,8 @@ The author is Alessandro Ranellucci.
       
        Support material options:
         --support-material  Generate support material for overhangs
+        --support-material-threshold
+                            Overhang threshold angle (range: 0-90, default: 45)
         --support-material-pattern
                             Pattern to use for support material (default: rectilinear)
         --support-material-angle

lib/Slic3r.pm

@@ -123,6 +123,7 @@ our $fill_angle         = 45;
 our $extra_perimeters   = 1;
 our $randomize_start    = 1;
 our $support_material   = 0;
+our $support_material_threshold = 45;
 our $support_material_pattern = 'rectilinear';
 our $support_material_angle = 0;
 our $support_material_tool = 0;

lib/Slic3r/Config.pm

@@ -284,6 +284,11 @@ our $Options = {
         cli     => 'support-material!',
         type    => 'bool',
     },
+    'support_material_threshold' => {
+        label   => 'Overhang threshold (°)',
+        cli     => 'support-material-threshold=i',
+        type    => 'i',
+    },
     'support_material_pattern' => {
         label   => 'Pattern',
         cli     => 'support-material-pattern=s',
@@ -292,7 +297,7 @@ our $Options = {
         labels  => [qw(rectilinear honeycomb)],
     },
     'support_material_angle' => {
-        label   => 'Angle (°)',
+        label   => 'Pattern angle (°)',
         cli     => 'support-material-angle=i',
         type    => 'i',
     },

lib/Slic3r/GUI/SkeinPanel.pm

@@ -86,7 +86,7 @@ sub new {
         },
         support_material => {
             title => 'Support material',
-            options => [qw(support_material support_material_tool)],
+            options => [qw(support_material support_material_threshold support_material_pattern support_material_angle support_material_tool)],
         },
     );
     $self->{panels} = \%panels;

lib/Slic3r/Print/Object.pm

@@ -2,7 +2,7 @@ package Slic3r::Print::Object;
 use Moo;
 
 use Slic3r::ExtrusionPath ':roles';
-use Slic3r::Geometry qw(scale unscale);
+use Slic3r::Geometry qw(scale unscale deg2rad);
 use Slic3r::Geometry::Clipper qw(diff_ex intersection_ex union_ex);
 use Slic3r::Surface ':types';
 
@@ -488,9 +488,10 @@ sub generate_support_material {
     my $self = shift;
     my %params = @_;
     
+    my $threshold_rad           = deg2rad($Slic3r::support_material_threshold + 1);   # +1 makes the threshold inclusive
+    my $overhang_width          = $threshold_rad == 0 ? undef : scale $Slic3r::layer_height * ((cos $threshold_rad) / (sin $threshold_rad));
     my $distance_from_object    = scale $Slic3r::flow->width;
-    my $extra_margin            = scale 1;
-    
+    printf "width = %s\n", unscale $overhang_width;
     # determine unsupported surfaces
     my @unsupported_expolygons = ();
     
@@ -517,8 +518,8 @@ sub generate_support_material {
             # we need an angle threshold for this
             my @overhangs = ();
             if ($upper_layer) {
-                @overhangs = @{diff_ex(
-                    [ map @$_, map $_->expolygon->offset_ex($extra_margin), @{$upper_layer->slices} ],
+                @overhangs = map $_->offset_ex(2 * $overhang_width), @{diff_ex(
+                    [ map @$_, map $_->expolygon->offset_ex(-$overhang_width), @{$upper_layer->slices} ],
                     [ map @{$_->expolygon}, @{$layer->slices} ],
                     1,
                 )};
@@ -547,8 +548,9 @@ sub generate_support_material {
     Slic3r::debugf "Generating patterns\n";
     my $support_patterns = [];  # in case we want cross-hatching
     {
+        # 0.5 makes sure the paths don't get clipped externally when applying them to layers
         my @support_material_areas = map $_->offset_ex(- 0.5 * scale $Slic3r::flow->width),
-            @{union_ex([ map @$_, @unsupported_expolygons ])};
+            @{union_ex([ map $_->contour, @unsupported_expolygons ])};
         
         my $fill = Slic3r::Fill->new(print => $params{print});
         my $filler = $fill->filler($Slic3r::support_material_pattern);

slic3r.pl

@@ -209,6 +209,8 @@ $j
   
    Support material options:
     --support-material  Generate support material for overhangs
+    --support-material-threshold
+                        Overhang threshold angle (range: 0-90, default: $Slic3r::support_material_threshold)
     --support-material-pattern
                         Pattern to use for support material (default: $Slic3r::support_material_pattern)
     --support-material-angle