Function PackAtlas

src/colmap/mvs/texture_mapping.cc:508–599

}

AtlasLayout PackAtlas(const std::vector<RegionProjection>& projections,
                      const std::vector<FaceRegion>& regions,
                      const int padding) {
  AtlasLayout layout;

  if (projections.empty()) {
    return layout;
  }

  struct RectEntry {
    int width;
    int height;
    size_t region_idx;
  };
  std::vector<RectEntry> rects(projections.size());
  int64_t total_area = 0;
  int max_rect_width = 0;

  for (size_t i = 0; i < projections.size(); ++i) {
    rects[i].width = projections[i].bbox_width + 2 * padding;
    rects[i].height = projections[i].bbox_height + 2 * padding;
    rects[i].region_idx = i;
    total_area += static_cast<int64_t>(rects[i].width) * rects[i].height;
    max_rect_width = std::max(max_rect_width, rects[i].width);
  }

  std::sort(
      rects.begin(), rects.end(), [](const RectEntry& a, const RectEntry& b) {
        return a.height > b.height;
      });

  const int atlas_side = std::max(
      static_cast<int>(std::ceil(std::sqrt(total_area * 1.3))), max_rect_width);
  int atlas_width = 1;
  while (atlas_width < atlas_side) atlas_width *= 2;
  int atlas_height = atlas_width;

  // Shelf packing.
  const auto TryPack = [&](const int aw,
                           const int ah,
                           std::vector<PackRect>& placements_out) -> bool {
    placements_out.resize(rects.size());
    int shelf_x = 0;
    int shelf_y = 0;
    int shelf_height = 0;

    for (size_t i = 0; i < rects.size(); ++i) {
      if (shelf_x + rects[i].width > aw) {
        shelf_y += shelf_height;
        shelf_x = 0;
        shelf_height = 0;
      }
      if (shelf_y + rects[i].height > ah) {
        return false;
      }
      placements_out[i].x = shelf_x + padding;
      placements_out[i].y = shelf_y + padding;
      placements_out[i].width = projections[rects[i].region_idx].bbox_width;