Material mtl = new Material(shader);
model = ellipse(mtl, 2.0f, 2.0f, 20);
addBehavior(new Billboard(model));
addBehavior(new Motion(vel, Vector3.zero()));
addBehavior(new TimeToLive(2.0f));
addBehavior(new Behavior() {
@Override
public void update() {
float f = 0.2f;