Selective Collisions?

Hey, I've a question; Is it possible I could enable colliders to selectively collide only under certain circumstances? Like, for example; I have a grenade which is thrown that produces a volume of smoke; I need the smoke to block AI vision therefore I need it return that it was struck in a raycast. However, say I have a projectile as a RigidBody but I need it to pass through smoke, as smoke clearly isn't solid to a bullet.

Is there a way I could do this?

 

Does a trigger still get registered from a Raycast?

 

you can setup collision layers in project settings -> physics.