static void convolve_two_polygon_sets(polygon_set& result, const polygon_set& a, const polygon_set& b) {
result.clear();
std::vector<polygon> a_polygons;
std::vector<polygon> b_polygons;
a.get(a_polygons);
b.get(b_polygons);
for(std::size_t ai = 0; ai < a_polygons.size(); ++ai) {
convolve_point_sequence_with_polygons(result, begin_points(a_polygons[ai]),
end_points(a_polygons[ai]), b_polygons);
for(typename polygon_with_holes_traits<polygon>::iterator_holes_type itrh = begin_holes(a_polygons[ai]);
itrh != end_holes(a_polygons[ai]); ++itrh) {
convolve_point_sequence_with_polygons(result, begin_points(*itrh),
end_points(*itrh), b_polygons);
}
for(std::size_t bi = 0; bi < b_polygons.size(); ++bi) {
polygon tmp_poly = a_polygons[ai];
result.insert(convolve(tmp_poly, *(begin_points(b_polygons[bi]))));
tmp_poly = b_polygons[bi];
result.insert(convolve(tmp_poly, *(begin_points(a_polygons[ai]))));
}
}
}
