physics.setDrag(0.15f);
physics.setWorldBounds(new AABB(new Vec3D(), 250));
physics.addBehavior(new GravityBehavior3D(new Vec3D(0, 0.2f, 0)));
physics.addBehavior(new AttractionBehavior3D(new Vec3D(), 500, 0.1f));
for (int i = 0; i < NUM_PARTICLES; i++) {
VerletParticle3D p = new VerletParticle3D(random(-250, 250), random(
-250, 250), random(-250, 250));
physics.addParticle(p);
for (int j = 0; j < i; j++) {
physics.particles.get(j).addBehavior(
new AttractionBehavior3D(p, 50, -0.9f, 0.02f),