sutherland-hodgman

template <typename T, typename F>
void sutherland_hodgman(const std::vector<T>& subject,
                        const std::vector<T>& clip,
                        const F& clip_test,
                        std::vector<T>& output) {
  output = subject;
  for (auto edge = clip.begin(), last = std::prev(clip.end()); edge != clip.end(); edge = std::next(edge)) {
    auto prev = last;
    std::vector<T> input = output;
    output.clear();
    for (auto p = input.begin(), last_p = std::prev(input.end()); p != input.end(); p = std::next(p)) {
      bool inside_prev = clip_test(*prev, *p);
      bool inside_edge = clip_test(*edge, *p);
      if (inside_prev && inside_edge) {
        output.push_back(*p);
      }
      else if (inside_prev) {
        output.push_back(intersect(*prev