public void remove(Object obj) {
if (obj instanceof PhysicsControl) {
((PhysicsControl) obj).setPhysicsSpace(null);
} else if (obj instanceof Spatial) {
Spatial node = (Spatial) obj;
PhysicsControl control = node.getControl(PhysicsControl.class);
control.setPhysicsSpace(null);
} else if (obj instanceof PhysicsCollisionObject) {
removeCollisionObject((PhysicsCollisionObject) obj);
} else if (obj instanceof PhysicsJoint) {
removeJoint((PhysicsJoint) obj);
} else {