Makes particles collide with geometry.
Here are the options you can set in the Collisions Options dialog box.
Sets how much rebound occurs. A value of 0 makes particles collide with no bounce. A value of 1 causes particles to rebound fully. A value between 0 and -1 makes the particles pass through the surface with refraction out the back side. Values greater than 1 or less than -1 add speed to the particles.
Sets how much the colliding particle’s velocity parallel to the surface decreases or increases as it bounces off the collision surface.
A value of 0 means that particles are unaffected by friction. A value of 1 makes particles reflect straight off along the normal of the surface. If Resilience is 0 while Friction is 1, the particles don’t bounce.
Only values between 0 and 1 correspond to natural friction. Values outside this range exaggerate the response.