Update and restore t/loops.t

t/loops.t

@@ -2,7 +2,6 @@ use Test::More;
 use strict;
 use warnings;
 
-plan skip_all => 'temporarily disabled';
 plan tests => 4;
 
 BEGIN {
@@ -12,46 +11,41 @@ BEGIN {
 }
 
 use Slic3r;
+use Slic3r::Geometry qw(Z epsilon scale);
 use Slic3r::Test;
 
 {
-    # We only need to slice at one height, so we'll build a non-manifold mesh
-    # that still produces complete loops at that height. Triangular walls are 
-    # enough for this purpose.
-    # Basically we want to check what happens when three concentric loops happen
+    # We want to check what happens when three concentric loops happen
     # to be at the same height, the two external ones being ccw and the other being
-    # a hole, thus cw.
-    my (@vertices, @facets) = ();
-    Slic3r::Test::add_facet($_, \@vertices, \@facets) for
-        # external surface below the slicing Z
-        [ [0,0,0],   [20,0,10],   [0,0,10]    ],
-        [ [20,0,0],  [20,20,10],  [20,0,10]   ],
-        [ [20,20,0], [0,20,10],   [20,20,10]  ],
-        [ [0,20,0],  [0,0,10],    [0,20,10]   ],
-        
-        # external insetted surface above the slicing Z
-        [ [2,2,10],   [18,2,10],  [2,2,20]    ],
-        [ [18,2,10],  [18,18,10], [18,2,20]   ],
-        [ [18,18,10], [2,18,10],  [18,18,20]  ],
-        [ [2,18,10],  [2,2,10],   [2,18,20]   ],
-        
-        # insetted hole below the slicing Z
-        [ [15,5,0],   [5,5,10],   [15,5,10]   ],
-        [ [15,15,0],  [15,5,10],  [15,15,10]  ],
-        [ [5,15,0],   [15,15,10], [5,15,10]   ],
-        [ [5,5,0],    [5,15,10],  [5,5,10]    ];
+    # a hole, thus cw. So we create three cubes, centered around origin, the internal
+    # one having reversed normals.
+    my $mesh1 = Slic3r::Test::mesh('20mm_cube');
     
-    my $mesh = Slic3r::TriangleMesh->new;
-    $mesh->ReadFromPerl(\@vertices, \@facets);
-    $mesh->analyze;
-    my @lines = map $mesh->intersect_facet($_, 10), 0..$#facets;
-    my $loops = Slic3r::TriangleMesh::make_loops(\@lines);
-    is scalar(@$loops), 3, 'correct number of loops detected';
-    is scalar(grep $_->is_counter_clockwise, @$loops), 2, 'correct number of ccw loops detected';
+    # center around origin
+    my $bb = $mesh1->bounding_box;
+    $mesh1->translate(
+        -($bb->x_min + $bb->size->x/2),
+        -($bb->y_min + $bb->size->y/2),  #//
+        -($bb->z_min + $bb->size->z/2),
+    );
     
-    my @surfaces = Slic3r::Layer::Region::_merge_loops($loops, 0);
-    is scalar(@surfaces), 1, 'one surface detected';
-    is scalar(@{$surfaces[0]->expolygon})-1, 1, 'surface has one hole';
+    my $mesh2 = $mesh1->clone;
+    $mesh2->scale(1.2);
+    
+    my $mesh3 = $mesh2->clone;
+    $mesh3->scale(1.2);
+    
+    $mesh1->reverse_normals;
+    ok $mesh1->volume < 0, 'reverse_normals';
+    
+    my $all_meshes = Slic3r::TriangleMesh->new;
+    $all_meshes->merge($_) for $mesh1, $mesh2, $mesh3;
+    
+    my $loops = $all_meshes->slice_at(Z, 0);
+    is scalar(@$loops), 1, 'one expolygon returned';
+    is scalar(@{$loops->[0]->holes}), 1, 'expolygon has one hole';
+    ok abs(-$loops->[0]->holes->[0]->area - scale($bb->size->x)*scale($bb->size->y)) < epsilon, #))
+        'hole has expected size';
 }
 
 __END__

xs/src/libslic3r/TriangleMesh.cpp

@@ -511,6 +511,13 @@ TriangleMesh::require_shared_vertices()
     if (this->stl.v_shared == NULL) stl_generate_shared_vertices(&(this->stl));
 }
 
+void
+TriangleMesh::reverse_normals()
+{
+    stl_reverse_all_facets(&this->stl);
+    if (this->stl.stats.volume != -1) this->stl.stats.volume *= -1.0;
+}
+
 void
 TriangleMesh::extrude_tin(float offset)
 {

xs/src/libslic3r/TriangleMesh.hpp

@@ -59,6 +59,7 @@ class TriangleMesh
     size_t facets_count() const;
     void extrude_tin(float offset);
     void require_shared_vertices();
+    void reverse_normals();
     
     static TriangleMesh make_cube(double x, double y, double z);
     static TriangleMesh make_cylinder(double r, double h, double fa=(2*PI/360));

xs/xsp/TriangleMesh.xsp

@@ -41,6 +41,7 @@
         %code{% RETVAL = THIS->bounding_box().center(); %};
     int facets_count();
     void reset_repair_stats();
+    void reverse_normals();
 
 %{