setFromRotation method

void setFromRotation(Matrix3 rotationMatrix)

Set the quaternion with rotation from a rotation matrix rotationMatrix.

Implementation

void setFromRotation(Matrix3 rotationMatrix) {
  final rotationMatrixStorage = rotationMatrix.storage;
  final trace = rotationMatrix.trace();
  if (trace > 0.0) {
    var s = math.sqrt(trace + 1.0);
    _qStorage[3] = s * 0.5;
    s = 0.5 / s;
    _qStorage[0] = (rotationMatrixStorage[5] - rotationMatrixStorage[7]) * s;
    _qStorage[1] = (rotationMatrixStorage[6] - rotationMatrixStorage[2]) * s;
    _qStorage[2] = (rotationMatrixStorage[1] - rotationMatrixStorage[3]) * s;
  } else {
    final i = rotationMatrixStorage[0] < rotationMatrixStorage[4]
        ? (rotationMatrixStorage[4] < rotationMatrixStorage[8] ? 2 : 1)
        : (rotationMatrixStorage[0] < rotationMatrixStorage[8] ? 2 : 0);
    final j = (i + 1) % 3;
    final k = (i + 2) % 3;
    var s = math.sqrt(rotationMatrixStorage[rotationMatrix.index(i, i)] -
        rotationMatrixStorage[rotationMatrix.index(j, j)] -
        rotationMatrixStorage[rotationMatrix.index(k, k)] +
        1.0);
    _qStorage[i] = s * 0.5;
    s = 0.5 / s;
    _qStorage[3] = (rotationMatrixStorage[rotationMatrix.index(k, j)] -
            rotationMatrixStorage[rotationMatrix.index(j, k)]) *
        s;
    _qStorage[j] = (rotationMatrixStorage[rotationMatrix.index(j, i)] +
            rotationMatrixStorage[rotationMatrix.index(i, j)]) *
        s;
    _qStorage[k] = (rotationMatrixStorage[rotationMatrix.index(k, i)] +
            rotationMatrixStorage[rotationMatrix.index(i, k)]) *
        s;
  }
}