getRotation method
Returns the rotation matrix from this homogeneous transformation matrix.
Implementation
Matrix3 getRotation() {
  final r = Matrix3.zero();
  copyRotation(r);
  return r;
}Returns the rotation matrix from this homogeneous transformation matrix.
Matrix3 getRotation() {
  final r = Matrix3.zero();
  copyRotation(r);
  return r;
}