Urgent exam on processing with an interactive installation

I'm going to have an exam in which I have to present a "simple" installation in processing, but I need a real help!

I understand the code but I can't create it...

My installation is about an interaction between people and many balls on the screen by a webcam.

Now this interaction works but I would like to have different results when the balls met.

One is the fusion of this two balls and the second is the explosion of one of this ellipse.

How I can do it?

Any suggestion?

I really need your help...

THANKS