public void setTransform(Mat4f xform) {
   Mat4f totalXform = xform.mul(offsetTransform);
   for (int i = 0; i < getNumChildren(); i++) {
     getChild(i).setTransform(totalXform);
   }
 }
 public ManipPartTransform() {
   super();
   offsetTransform = new Mat4f();
   offsetTransform.makeIdent();
 }