use even/odd polygon filling rule ref https://github.com/mapbox/tilemill/issues/2110

src/agg/process_polygon_pattern_symbolizer.cpp

@@ -166,6 +166,7 @@ void agg_renderer<T>::process(polygon_pattern_symbolizer const& sym,
         }
     }
     agg::scanline_u8 sl;
+    ras_ptr->filling_rule(agg::fill_even_odd);
     agg::render_scanlines(*ras_ptr, sl, rp);
 }
 

src/agg/process_polygon_symbolizer.cpp

@@ -98,6 +98,7 @@ void agg_renderer<T>::process(polygon_symbolizer const& sym,
     renderer_type ren(renb);
     ren.color(agg::rgba8_pre(r, g, b, int(a * sym.get_opacity())));
     agg::scanline_u8 sl;
+    ras_ptr->filling_rule(agg::fill_even_odd);
     agg::render_scanlines(*ras_ptr, sl, ren);
 
 }

src/cairo_renderer.cpp

@@ -334,6 +334,7 @@ void cairo_renderer_base::process(polygon_symbolizer const& sym,
         }
     }
     // fill polygon
+    context_.set_fill_rule(CAIRO_FILL_RULE_EVEN_ODD);
     context_.fill();
 }
 
@@ -871,6 +872,7 @@ void cairo_renderer_base::process(polygon_pattern_symbolizer const& sym,
         }
     }
     // fill polygon
+    context_.set_fill_rule(CAIRO_FILL_RULE_EVEN_ODD);
     context_.fill();
 }
 

src/grid/process_polygon_pattern_symbolizer.cpp

@@ -84,6 +84,7 @@ void grid_renderer<T>::process(polygon_pattern_symbolizer const& sym,
     // render id
     ren.color(color_type(feature.id()));
     agg::scanline_bin sl;
+    ras_ptr->filling_rule(agg::fill_even_odd);
     agg::render_scanlines(*ras_ptr, sl, ren);
 
     // add feature properties to grid cache

src/grid/process_polygon_symbolizer.cpp

@@ -86,6 +86,7 @@ void grid_renderer<T>::process(polygon_symbolizer const& sym,
     // render id
     ren.color(color_type(feature.id()));
     agg::scanline_bin sl;
+    ras_ptr->filling_rule(agg::fill_even_odd);
     agg::render_scanlines(*ras_ptr, sl, ren);
 
     // add feature properties to grid cache