Hi blair,

I write them in C++, using libraries like OpenCV for vision, and this one uses a 2D physics library called chipmunk.

I've been writing computer vision software for a living for several years now, so I am able to put all those skills to good use when writing stuff like this.

I'd really like to play with quartz composer, write some filters for it. That'll have to wait till I can afford a mac, though ;-)