Method extract_triangles

source/MRMesh/miniply.cpp:1087–1172

  bool PLYReader::extract_triangles(uint32_t propIdx, const float pos[], uint32_t numVerts, PLYPropertyType destType, void *dest) const
  {
    if (!requires_triangulation(propIdx)) {
      return extract_list_property(propIdx, destType, dest);
    }

    const PLYElement* elem = element();
    const PLYProperty& prop = elem->properties[propIdx];

    const uint32_t* counts = prop.rowCount.data();
    const uint8_t*  data   = prop.listData.data();

    uint8_t* to = reinterpret_cast<uint8_t*>(dest);

    bool convertSrc = !compatible_types(elem->properties[propIdx].type, PLYPropertyType::Int);
    bool convertDst = !compatible_types(PLYPropertyType::Int, destType);

    size_t srcValBytes  = kPLYPropertySize[uint32_t(prop.type)];
    size_t destValBytes = kPLYPropertySize[uint32_t(destType)];

    if (convertSrc && convertDst) {
      std::vector<int> faceIndices, triIndices;
      faceIndices.reserve(32);
      triIndices.reserve(64);
      const uint8_t* face = data;
      for (uint32_t faceIdx = 0; faceIdx < elem->count; faceIdx++) {
        const uint8_t* faceEnd = face + srcValBytes * counts[faceIdx];
        faceIndices.clear();
        faceIndices.reserve(counts[faceIdx]);
        for (; face < faceEnd; face += srcValBytes) {
          int idx = -1;
          copy_and_convert_to(&idx, face, prop.type);
          faceIndices.push_back(idx);
        }

        triIndices.resize((counts[faceIdx] - 2) * 3);
        triangulate_polygon(counts[faceIdx], pos, numVerts, faceIndices.data(), triIndices.data());
        for (int idx : triIndices) {
          copy_and_convert(to, destType, reinterpret_cast<const uint8_t*>(&idx), PLYPropertyType::Int);
          to += destValBytes;
        }
      }
    }
    else if (convertSrc) {
      std::vector<int> faceIndices;
      faceIndices.reserve(32);
      const uint8_t* face = data;
      for (uint32_t faceIdx = 0; faceIdx < elem->count; faceIdx++) {
        const uint8_t* faceEnd = face + srcValBytes * counts[faceIdx];
        faceIndices.clear();
        faceIndices.reserve(counts[faceIdx]);
        for (; face < faceEnd; face += srcValBytes) {
          int idx = -1;
          copy_and_convert_to(&idx, face, prop.type);
          faceIndices.push_back(idx);
        }

        uint32_t numTris = triangulate_polygon(counts[faceIdx], pos, numVerts, faceIndices.data(), reinterpret_cast<int*>(to));