Particle simulation
 

Hello. I am trying to use Vizard to simulate light particles (represented as balls). I need them to be able to do two things and I'm unsure how to achieve these effects:

1) the particles need to be able to collide with other objects but not each other

2) The particles must be able to interact with an optical surface such as a lens (represented as a tex quad) by either changing angle of trajectory or bouncing off (based on incident angle).

Any suggestions would be appreciated.