How to mask meshes inside a trigger sphere

Hi,

Is there a way to swap/mask actors that are inside a trigger box or sphere? What I’m trying to achieve is a way to have objects in a level that can only be used inside a trigger box or sphere. Then I would make the trigger size animate from 0 to the size I need to reveal the objects. But also the objects that where in that place would then be hidden.
Think of it as sort of a time portal.

I think custom depth could solve a part of this problem, but I can’t figure out how to approach the physical part so that the player can only interact with the objects that are visible.


Thanks Omnicypher! the opacity video helps a lot on the visual part and also gave me an idea to solve the physical problem.