by this:
public Particle() {
super(1);
addTriangle(new SimpleVector(-1, -1, 0), 0, 0, new SimpleVector(1, 1, 0), 1, 1, new SimpleVector(1, -1, 0), 1, 0);
getMesh().compress();
setBillboarding(Object3D.BILLBOARDING_ENABLED);
setAdditionalColor(RGBColor.WHITE);
setLighting(Object3D.LIGHTING_NO_LIGHTS);
enableLazyTransformations();
setVisibility(Object3D.OBJ_INVISIBLE);
//setRenderHook(rh);
build();
}