Screenshot Object recording

I am currently developing a game that acts similar to Pokemon snap. That is, the players will be allowed to take pictures throughout the game (using the screenshot option), and be scored bsaed on what they have taken pictures of.

The problem I am currently running into is how to record what has been photographed. I have tried setting up the photo taking tool as a weapon and record what objects that "weapon" has shot. However, this isn't working as well as I had hoped.

Can anyone suggest a way that I could just keep track of what has been captured by the screenshot? I figure there should be something in the way the camera object works, that lets the engine know what is to be rendered, and I should be able to manipulate this into whhat I need. Unfortunately, looking over the camera.h and .cc files hasn't really helped.

Any help or suggestions would be appreciated.

Thanks
GG