Reflective Surfaces

Hi all, I''ve been cooking my brain trying to come up with a practical way to do a reflective surface (i.e. mirror) in OpenGL. If anyone could help me out (even with just some theory, not OGL-specific stuff), that would rock my world. I know in theory what I should be rendering (calculating angle of incidence (from eye) to surface, and reversing it, then treating the plane normal to this as a viewport to project to... its kinda hard to put into words, but I know what I''m getting at ), but I''m having trouble deciding on how to actually determine what to draw, and how to map it onto a poly. Can I have a separate OpenGL state machine which treats this surface as a viewport, projecting onto the poly (I know, it sounds very unlikely to me too)? I assume I have to implement some sort of (software) clipping and hidden surface determination, and ''project'' what can be ''seen'' onto a texture, which I then apply to the poly (does this sound feasible?). This sounds like a real bitch, ''coz I want it to work with a perspective projection (i.e. a clipping frustum, rather than a ''box''... screw doing that in software ) Would environment mapping do this, or is that just a smoke-and-mirrors (d''oh, bad analogy ) way of doing reflection? Even some links on the topic would be much appreciated. Thankyou, bye. ------------- squirrels are a remarkable source of protein...