Backface Emission


Is there any way to set a simulation so that there is no emission from the backface of an object? It seems that volume/particles emit equally from both normal and backfaces (as in the picture below, most of the fire is emitting from the right, which is the backface in this case):

Obviously, it just looks this way because I have a collider, but it would be better for optimisation (I assume) is volume isn’t emitting from an unseen face. This would prevent volumes emitting from backfaces displaying like this also (in areas not occluded by an object):

Screenshot 2024-03-14 103308

Or, similarly, it would be good to have some kind of emission ‘normal bias’ value or something similar, so that you can set the extent from which particles/volume emits from the normal/backface of an object.

Any feedback is much appreciated!

Kind regards,


Hey you can either vertex paint that object and use the “Mask” tab of the import node to emit on only the painted parts. Or you can create a collider and place it where you don’t want emission to happen and then make it invisible.

Either of these should work for your purposes!