TH> I've read somewhere that DOOM uses raycasting (like Wolf3d) but
 TH> double. One along the ceiling and one along the floor. Is there any
 TH> truth to that?
Hmm... No, I don't think so.. I'm pretty sure that it just does basically 3d 
to 2d transforms etc, and rotates all the points in two dimensions.. Unless 
they did some kinda raycasting technique for the floors and ceilings, but, 
again, I'm not sure, but I think not..  Unfortunately, I don't think iD would 
be willing to answer such questions, (then again, maybe they would)
Oh, actually, it IS wide known that DOOM uses BSP trees, and I can't quite 
see how they'd fit in with raycasting, because raycasting basically takes 
care of all the hidden surfaces etc for you, as that's what the algorithm is 
all about, drawing what you can see by tracing invisible rays through maps 
etc..
So, yeh, I think it doesn't use raycasting..
Sam
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