My original thought was to take a snapshot of "what the mirror sees". I figured I could use the distance from the mirror, the angle to the plane of the mirror, and the mirrors (EDIT - I actually typed windows here, that to me is kinda funny) size to determine its field of view. From that I could calculate what parts of my scene would be visible in the mirror. I stumbled on the actual projection of a 3d scene onto a 2d image, which led me to just recreating everything for a simple illusion, it would be totally expensive to do this for an intricate scene or for multiple mirrors.
Besides the actual game implementation of this, my question was actually kinda leaning towards the physical/dimensional properties of whats going on. More to real life multi-dimensional universes, multiverses whatever you call it, the concept of having anything to do with a mirror is just silly but it did get me thinking about light. The reason I asked this question at all is as follows (ignore me if its just plain stupid)
I take room A and place a mirror on a wall, recreate that room and call it room B, place a mirror on a wall perpendicular to the first. Then recreate the room again room C. Looking into room C at the right angle will show the mirror that looks into room B, so Ill create a 4th room but is it D or B? or both....I would have multiple copies of the same thing in the same place. Stupid to try to applicate but too much to comprehend as far as what it would look like and I lost it. This is probably extremely retarded but some things just get me to thinking. Here's a diagram of what I was thinking just incase anyone is still paying any attention.
Maybe I would have to think about another dimension?