@Override
 public Space newEdgeSpace(Object edge, Box pa, Box pb) {
   return new Line3D(pa.getPosition(), pb.getPosition(), new DoubleVar(0.02), 2);
 }
 @Override
 public Space newEdgeSpace(Object edge, Box pa, Box pb) {
   Line3D fl = new Line3D(pa.getPosition(), pb.getPosition(), new DoubleVar(0.02), 2);
   fl.color(Color.newRandomHSB(0.5, 0.5));
   return fl;
 }