Collider

Master toggle for the Collider group. Unchecked (default): particles move freely through any assigned Collider Layer. Check to enable physical collisions.

Collider Layer

Collider off

Collider on (layer assigned)

AE layer whose alpha defines solid regions.

Collider Mode

Outside (shape is solid)

Inside (shape is a container)

Outline (only the edge is solid)

Outside: particles can't enter the shape. Inside: particles can't leave (water-in-a-bottle). Outline: only the edge is solid (pass through the interior, can't cross the boundary).