I have an 3D helmet I'm placing on a Live action head... I don't want to see the underside of the helmet (since the head exists under it, I shouldn't see the underside) ... Is there a way to make a material to subtract COMPLETELY and make it go straight to alpha channel?
I do have a 3D head under the helmet to use as the material that would block/ remove the underside of the helmet.

And here's the section I want to have removed/ hidden/ Alpha Channeled
