Function getNodeTransform

CesiumGltf/src/Model.cpp:440–503

}

std::optional<glm::dmat4x4> getNodeTransform(const CesiumGltf::Node& node) {
  if (!node.matrix.empty() && node.matrix.size() < 16) {
    return std::nullopt;
  }

  // clang-format off
  // This is column-major, just like glm and glTF
  static constexpr std::array<double, 16> identityMatrix = {
      1.0, 0.0, 0.0, 0.0,
      0.0, 1.0, 0.0, 0.0,
      0.0, 0.0, 1.0, 0.0,
      0.0, 0.0, 0.0, 1.0};
  // clang-format on

  const std::vector<double>& matrix = node.matrix;

  if (node.matrix.size() >= 16 && !std::equal(
                                      identityMatrix.begin(),
                                      identityMatrix.end(),
                                      matrix.begin())) {
    return glm::dmat4x4(
        glm::dvec4(matrix[0], matrix[1], matrix[2], matrix[3]),
        glm::dvec4(matrix[4], matrix[5], matrix[6], matrix[7]),
        glm::dvec4(matrix[8], matrix[9], matrix[10], matrix[11]),
        glm::dvec4(matrix[12], matrix[13], matrix[14], matrix[15]));
  }

  if (!node.translation.empty() || !node.rotation.empty() ||
      !node.scale.empty()) {
    glm::dmat4x4 translation(1.0);
    if (node.translation.size() >= 3) {
      translation[3] = glm::dvec4(
          node.translation[0],
          node.translation[1],
          node.translation[2],
          1.0);
    } else if (!node.translation.empty()) {
      return std::nullopt;
    }

    glm::dquat rotationQuat(1.0, 0.0, 0.0, 0.0);
    if (node.rotation.size() >= 4) {
      rotationQuat[0] = node.rotation[0];
      rotationQuat[1] = node.rotation[1];
      rotationQuat[2] = node.rotation[2];
      rotationQuat[3] = node.rotation[3];
    } else if (!node.rotation.empty()) {
      return std::nullopt;
    }

    glm::dmat4x4 scale(1.0);
    if (node.scale.size() >= 3) {
      scale[0].x = node.scale[0];
      scale[1].y = node.scale[1];
      scale[2].z = node.scale[2];
    } else if (!node.scale.empty()) {
      return std::nullopt;
    }