I'm doing a project at university and I want to use the mirror function in processing with my videocamera in a live feed. This works quite well, I played around with the base code to get a larger image and it is a bit slow but ok for now. The main question I have is this;

How can I set up a motion sensor (IR, movement, temperature, light or whatever) to trigger the camera?

The set up is this; I want to use my computer as a mirror but what a person sees when they look into it is the back of their head, like the painting by Rene Magritte. If possible I want the camera to track the person so that even if they move in front of the 'mirror' they will never see their face.

This is puzzling me, I have spent ages looking at Arduino but I can't find a solution there and my knowledge of Processing is still at basic level so I need some pointers please.

All answers gratefully received.

Many thanks,

Frank