I'm trying to create what should be a relatively simple effect. But it depends on particle particle collision information and this is where I am stuck.

Problem: I have two nParticle shapes, one of which has only one particle for simplicity (particleShapeB). Any time a particle from particleShapeA collides with shapeB, I would like that particle to change color.

What I'm trying: I've experimented with calling an event procedure with the Particle Collision Event Editor, but this is very very slow, because it calls a procedure for every frame for every particle that collides with anything. And, I don't know how to modify a per particle attribute in a global procedure. Or how to get that info into a runtime expression.

I've also been looking into SOuP, because it seems there are some pretty powerful nodes with attribute transfer and all that, but I'm still stuck on how to tie that to collisions.

Thanks for any ideas!