nParticles: Any way to get a one sided collider?


Essentially I am trying to get particles to enter a box but then be contained within the box while more particles can still enter. I would use “collideStrengthPP” and just change that value when the particles cross the barrier, but all of this is within a larger box which needs to be a boundary the particles stay inside of when they are outside the smaller box, so they need to collide with the larger box the entire time. I also looked for a collisionLayerPP attribute, which would solve the issue, but I didn’t find one.

What I really want is a way I can make the particles treat the surface normal of the (smaller) box the way a game engine does with light where you see the surface when the normal is facing you, but when it is facing away from you it is invisible. That way I could make the box’s face normals all face inside so the particles can enter, but will collide with the walls instead of being able to leave.

Like a Roach Motel. The particles check in but they don’t check out!

Anybody know of a way I can set this up?


Easy with standard Maya particles.