When the player takes a photo I duplicate the environment, make it greyscale and slice the meshes to remove anything outside the photo. When they place it into the world I slice the environment's meshes to make a hole for the photo.
Here's what happens when you photograph half a crate...
The thing that is fascinating about this is that it's not even recursive, it's more like... tail call flattening? Portal inlining?
I guess there won't be an analogous name because in the analogy this would be a bug? It's like somebody learned about memoization in class today and then while stoned they "improved" the language interpreter you're using by making every function call into an auto-memoized version of itself. Look how much faster you can get wrong answers now!
Talk about a brainfuck!
What, no xscreensaver tag?