// so we need to get the global transform.
Transform3D transform3D = getGlobalTransform3D(node);
// we need to detach before changing the global transform, or it will move the group too far
groupToFall.detach();
tg.setTransform(transform3D);
Interpolator gravity = createGravityInterpolator(tg);
addToUniverse(groupToFall, gravity);
}