How to make an FOV based scope that cant see the scope interior?

Hey guys,

Wondering if anybody knows how this is done in games.

When using FOV to zoom the screen in order to replicate a scope zoom, you encounter a problem where you can see the inside of the scope housing. In games like battlefield/cod, it almost looks like picture in picture, where you have a lens almost acting as a screen, but as far as I know, they are definitely dont use PIP.

Its almost like the back of the scope gets kept and the rest gets hidden? Do you know how games do this?



I’m pretty sure they use a specific overlay on top of the rest of the image, rather than trying to make it work with “physics.”
This also makes it easier to add lens-specific effects like aberration etc.

This dosent solve the issue though. Ive been able to implement overlays and lens effects, but the one part that I cant understand how to avoid is not being able to see the inside/front of the scope while looking down the scope. In AAA games you can only see the sight picture, lens and back of the scope, the interior of the scope and the front of the scope isnt visible at all.

You can hide the gun/scope actor while the user is zoomed in, and let the overlay picture take care of “showing the scope.”

If there’s another specific effect you want, some pictures would probably help explain what the problem is.