setRay method
Set the AABB to enclose a limited ray (or line segment) that is limited
by limitMin and limitMax.
Implementation
void setRay(Ray ray, double limitMin, double limitMax) {
  ray
    ..copyAt(_min, limitMin)
    ..copyAt(_max, limitMax);
  if (_max.x < _min.x) {
    final temp = _max.x;
    _max.x = _min.x;
    _min.x = temp;
  }
  if (_max.y < _min.y) {
    final temp = _max.y;
    _max.y = _min.y;
    _min.y = temp;
  }
  if (_max.z < _min.z) {
    final temp = _max.z;
    _max.z = _min.z;
    _min.z = temp;
  }
}