your skirt analogy doesn’t hold up at all. we’re trying to create a skirt on top of the body that doesn’t also need to make all the fancy features of the body behind it.
how do you put a range on something “within the material” if dynamic shader branching isn’t even there?
also the point of using deferred decals is to greatly reduce the cost of such icing on the cake. they are deferred, they have access to all the buffers that are already written in that frame. you know what that means right? you sample what’s already there instead of having to duplicate the same functionality in a different material