On Monday 31 January 2005 09:48, Timothy Miller wrote: > > In case (1) a nice optimization would be to do the perspective > > divide only every second pixel and linearly interpolate for the > > other. This adds more logic, but it could conceivably be a way to > > get to a 4x pixel unit design within the limited supply of > > multipliers. > > I've thought about things like that. I'm not sure what effect it > would have on the image quality.
It's barely noticeable but only suitable for GL_FASTEST mode anyway. Quake and Quake II used 16 pixel interpolated spans. You can see slight distortion artifacts if you know what to look for (granted, the whole image is noisy and dark which tends to cover things up). With this interpolation, pixel pairs should be aligned modulo 2 to the screen pixels, that is, not relative to the polygon edge, otherwise a slight ripple effect appears on polygons clipped against the left edge. This is a nice technique in software, but maybe in hardware it doesn't save anything unless you can dynamically reassign the saved multipliers to other functions, yet more work. On the other hand, somebody determined enough and with enough time on their hands might be able to squeeze four pixels per clock out of the card this way, subject to memory limitations you mentioned. Not that I can really see why you'd need 800 Megapix/Sec except perhaps for full screen antialiasing, which is likely out of reach anyway. Thanks for the answers on the dual pixel pipeline, it sounds ideal. Regards, Daniel _______________________________________________ Open-graphics mailing list [email protected] http://lists.duskglow.com/mailman/listinfo/open-graphics List service provided by Duskglow Consulting, LLC (www.duskglow.com)
