On Mon, Apr 08, 2002 at 06:17:59PM -0700, Raystonn wrote: | As far as the reading of pixels from the framebuffer, this is a highly | inefficient thing to do, no matter the hardware.
It doesn't have to be; that's just a tradeoff made by the hardware designers depending on the applications for which their systems are intended. Reading previously-rendered pixels is useful for things like dynamically-constructed environment maps, shadow maps, correction for projector optics, film compositing, and parallel renderers. There are various ways hardware can assist these operations, and various ways tiled renderers interact with them, but that discussion is too lengthy for this note. At any rate, the ability to use the results of previous renderings is a pretty important capability. | I still maintain that immediate mode renderering is an inefficient algorithm | designed to favor the use of memory over computations. An important design characteristic of immediate mode is that it allows the application to determine the rendering order. This helps achieve certain rendering effects (such as those Steve described earlier), but it can also be a *huge* efficiency win if the scene involves expensive mode changes, such as texture loads/unloads. Check out the original Reyes paper for a good quantitative discussion of this sort of issue. Allen _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
