Handle polygons' triangulation

Graphic polygons may be invalid and so need to be explicitly simplified
before triangulation.

Also clean up hole handling in triangulation routine

libs/kimath/include/geometry/shape_poly_set.h

@@ -508,8 +508,9 @@ public:
      * in partition calculations the grid size is hard coded to 1e7.
      * This is a good value for Pcbnew: 1cm, in internal units.
      * But not good for Gerbview (1e7 = 10cm), however using a partition is not useful.
+     * @param aSimplify = force the algorithm to simplify the POLY_SET before triangulating
      */
-    void CacheTriangulation( bool aPartition = true );
+    void CacheTriangulation( bool aPartition = true, bool aSimplify = false );
     bool IsTriangulationUpToDate() const;
 
     MD5_HASH GetHash() const;

libs/kimath/src/geometry/shape_poly_set.cpp

@@ -2681,7 +2681,7 @@ static SHAPE_POLY_SET partitionPolyIntoRegularCellGrid( const SHAPE_POLY_SET& aP
 }
 
 
-void SHAPE_POLY_SET::CacheTriangulation( bool aPartition )
+void SHAPE_POLY_SET::CacheTriangulation( bool aPartition, bool aSimplify )
 {
     bool recalculate = !m_hash.IsValid();
     MD5_HASH hash;
@@ -2752,18 +2752,34 @@ void SHAPE_POLY_SET::CacheTriangulation( bool aPartition )
         {
             // This partitions into regularly-sized grids (1cm in Pcbnew)
             SHAPE_POLY_SET flattened( Outline( ii ) );
+
+            for( int jj = 0; jj < HoleCount( ii ); ++jj )
+                flattened.AddHole( Hole( ii, jj ) );
+
             flattened.ClearArcs();
+
+            if( flattened.HasHoles() )
+                flattened.Fracture( PM_FAST );
+            else if( aSimplify )
+                flattened.Simplify( PM_FAST );
+
             SHAPE_POLY_SET partitions = partitionPolyIntoRegularCellGrid( flattened, 1e7 );
 
-            m_triangulationValid &= triangulate( partitions, ii, m_triangulatedPolys );
+            // This pushes the triangulation for all polys in partitions
+            // to be referenced to the ii-th polygon
+            m_triangulationValid &= triangulate( partitions, ii , m_triangulatedPolys );
         }
     }
     else
     {
         SHAPE_POLY_SET tmpSet( *this );
 
+        tmpSet.ClearArcs();
+
         if( tmpSet.HasHoles() )
             tmpSet.Fracture( PM_FAST );
+        else if( aSimplify )
+            tmpSet.Simplify( PM_FAST );
 
         m_triangulationValid = triangulate( tmpSet, -1, m_triangulatedPolys );
     }

pcbnew/pcb_painter.cpp

@@ -1701,7 +1701,7 @@ void PCB_PAINTER::draw( const PCB_SHAPE* aShape, int aLayer )
                     // draw the polygon solid shape on Opengl.  GLU tessellation is much slower,
                     // so currently we are using our tessellation.
                     if( m_gal->IsOpenGlEngine() && !shape.IsTriangulationUpToDate() )
-                        shape.CacheTriangulation();
+                        shape.CacheTriangulation( true, true );
 
                     m_gal->DrawPolygon( shape );
                 }