* Index of the sphere
*/
void randomSphere(final int i) {
// Crate a sphere and position it.
final Sphere sphere = new Sphere("sphere" + i, 18, 18, MathUtils.nextRandomDouble() * 1.75 + 1.25);
sphere.updateModelBound();
sphere.setTranslation(new Vector3(rand.nextDouble() * worldsize * 2 - worldsize, rand.nextDouble() * worldsize
* 2 - worldsize, rand.nextDouble() * worldsize * 2 - worldsize));
_root.attachChild(sphere);
}