Originally posted by Bob:
I also thought the four “side-planes” went through the origin, and therefore had a D-component of zero. However, in these equations, I always get non-zero values for D. I’m a little but suspicious about the correctness. But what boggels me is that whatever culling I try to do, it always gives me the correct results. So after all, it seems like they indeed are correct.
No, the clipping planes dont necessarily run through the origin. They run through the viewpoint. If you translate all world geometry by (-viewpoint.X, -viewpoint.Y, -viewpoint.Z), THEN the clipping planes will all (except near and far planes) go through the origin (but this is wasteful and slow).
[This message has been edited by LordKronos (edited 01-14-2001).]