public void showVelocity(boolean on) {
		for (int i = 0; i < model.getAtomCount(); i++) {
			if (on) {
				Atom at = model.getAtom(i);
				viewer.setAtomVelocities(i, at.getVx(), at.getVy(), at.getVz());
			}
			velocityBitSet.set(i, on);
		}
		repaint();
	}