Function eliminate_overlaps

src/svgfill/src/arrange_polygons.cpp:510–668

};

void eliminate_overlaps(DebugWriter& debug_writer, double OVERLAP_RESOLUTION_DISTANCE, std::vector<Polygon_2>& polygons) {
    // solve overlaps by means of subtraction
    // loop over overlaps and subtract the smaller polygon from the larger one

    std::set<size_t> eliminated_polies;

    /*
    std::map<size_t, size_t> overlap_counts;
    for (auto& p : overlaps) {
        overlap_counts[p.first]++;
        overlap_counts[p.second]++;
    }
    */

    auto overlaps = find_overlaps(polygons);

    for (const auto& edge : overlaps) {
        // Skip eliminated
        if (eliminated_polies.find(edge.first) != eliminated_polies.end() ||
            eliminated_polies.find(edge.second) != eliminated_polies.end()) {
            continue;
        }

        // Many overlaps indicate an aggregated polygon, skip them
        /*
        if (overlap_counts[edge.first] > 10 || overlap_counts[edge.second] > 10) {
            if (overlap_counts[edge.first] > 10) {
                eliminated_polies.insert(edge.first);
            }
            if (overlap_counts[edge.second] > 10) {
                eliminated_polies.insert(edge.second);
            }
            continue;
        }
        */

        // these are pointers now, because otherwise swap would not work?
        auto* poly1 = &polygons[edge.first];
        auto* poly2 = &polygons[edge.second];

        // @todo this is applied during overlap processing, maybe better after the boolean operation,
        // because they can be come small or narrow when overlaps are resolved

        // Populate eliminated_polies with small polygons
        // This can happen over time when modifications are made to the polygons to solve overlaps
        bool skip = false;
        if (poly1->area() < 1.e-2) {
            eliminated_polies.insert(edge.first);
            skip = true;
        }
        if (poly2->area() < 1.e-2) {
            eliminated_polies.insert(edge.second);
            skip = true;
        }
        // Small slivers are also just eliminated
        if (!maybe_take_first_if_single_item(create_and_convert_offset_polygon(-1.e-1, *poly1))) {
            eliminated_polies.insert(edge.first);
            skip = true;