inline void applyMaskToVertexesAndFaces()

in source/render/MeshUtil.h [345:405]

• 51 lines of code
• 12 McCabe index (conditional complexity)

inline void applyMaskToVertexesAndFaces(
    Eigen::MatrixXd& vertexes,
    Eigen::MatrixXi& faces,
    const cv::Mat_<bool> mask) {
  const int width = mask.cols;
  const int height = mask.rows;
  CHECK_EQ(width * height, vertexes.rows());
  bool* originalVertexMask = (bool*)mask.data;

  // Keep faces only if all vertexes have a non-zero mask
  std::vector<int> outputFaceIndexes;
  for (int i = 0; i < faces.rows(); ++i) {
    const Eigen::Vector3i& face = faces.row(i);
    bool allVertexesRetained = true;
    for (int j = 0; j < face.size(); ++j) {
      if (!originalVertexMask[face(j)]) {
        allVertexesRetained = false;
        break;
      }
    }
    if (allVertexesRetained) {
      outputFaceIndexes.push_back(i);
    }
  }

  // Keep only vertexes of retained faces
  std::vector<bool> vertexMask(vertexes.rows(), false);
  for (int i : outputFaceIndexes) {
    const Eigen::Vector3i& face = faces.row(i);
    for (int j = 0; j < face.size(); ++j) {
      vertexMask[face(j)] = true;
    }
  }

  // Compute mapping between old and new vertex indices
  std::map<int, int> inputToOutputVertexIndexes;
  int numOutputVertexes = 0;
  for (int i = 0; i < vertexes.rows(); ++i) {
    if (vertexMask[i]) {
      inputToOutputVertexIndexes[i] = numOutputVertexes++;
    }
  }

  // create output vertex matrix
  Eigen::MatrixXd inputVertexes = vertexes;
  vertexes = Eigen::MatrixXd(numOutputVertexes, 3);
  for (auto iter = inputToOutputVertexIndexes.begin(); iter != inputToOutputVertexIndexes.end();
       ++iter) {
    vertexes.row(iter->second) = inputVertexes.row(iter->first);
  }

  // Create output face matrix and re-index vertexes
  Eigen::MatrixXi inputFaces = faces;
  faces = Eigen::MatrixXi(outputFaceIndexes.size(), 3);
  for (ssize_t i = 0; i < ssize(outputFaceIndexes); ++i) {
    const Eigen::Vector3i& face = inputFaces.row(outputFaceIndexes[i]);
    for (int j = 0; j < face.size(); ++j) {
      faces(i, j) = inputToOutputVertexIndexes[face(j)];
    }
  }
}