Those are models not “types”.
The types I see in the video are only acog and red dot.
They can all occlude the gun the same way. That is red dot does not.
Acog can if above x2
Re multiplayer. It does matter if you just render the gun with the same material.
It will disappear when the enemy aims down sight unless you use different weapons.
Re the rest.
Maybe editing the engine for a specific purpose is not such a bad idea if the scope of the project requires it.
I don’t blame him at all for wanting a better solution, but I think the focus is in the wrong place.
A “better” solution is not going to make the gameplay any better is it?
A proper solution (like your pass sampling) would…