Hello @sly I could just give you the answer and code it for you in a few minutes, but what fun would that be! Surely you’d be happier if I were to link to a tutorial related to your problem. You could learn while you work! Great fun for everybody!
@jhl sent you in a direction related to your problem, but I have a feeling it didn’t help very much. See if you can learn from this tutorial, and apply that to your problem. Good luck!