@Override
 public WB_Vector nextVector() {
   final double t = 2 * Math.PI * randomGen.nextDouble();
   return new WB_Vector(
       radius * Math.cos(t), radius * Math.sin(t), height * randomGen.nextCenteredDouble());
 }
 @Override
 public void reset() {
   randomGen.reset();
 }
 @Override
 public WB_RandomOnCylinder setSeed(final long seed) {
   randomGen.setSeed(seed);
   return this;
 }