On Sunday 13 March 2005 01:25, Daniel Phillips wrote: > On Saturday 12 March 2005 15:48, Lourens Veen wrote: > > On Saturday 12 March 2005 21:00, Daniel Phillips wrote: > > > On Saturday 12 March 2005 02:33, Lourens Veen wrote: > > > > I've been thinking, would it be acceptable to lose the hardware > > > > overlay scaler when FSAA is turned on, and/or to only have FSAA > > > > in full-screen OpenGL mode? > > > > > > Why do you think the two are incompatible? > > > > Well, if you use the hardware overlay scaler for FSAA you can't also > > use it for playing video...that is my idea below makes them > > incompatible. > > FSAA doesn't use a scaler, it uses a simple averaging filter. > > > > Why does video need a dedicated scaler instead of being handled as > > > a texture? This just leaves the YUV->RGB conversion, which can be > > > a property of the window, picked up by the window ownership test. > > > > > > But do we really need YUV->RGB on the card? Why not do this on the > > > host? > > > > That's been discussed before...seems like there was never really a > > decision taken. > > http://lists.duskglow.com/open-graphics/2004-November/000032.html > > It should be pretty easy to make that decision now. The hardware budget > doesn't leave any room for extras that can already be accomplished with > the existing 3D pipeline. MPlayer et al know how to convert YUV, so > the card doesn't need to. Host CPU overhead is unlikely to be an issue > here. > > A question nobody raised yet: what about running FSAA in a window? > Although it is possible to map all non-FSAA graphics transparently to > FSAA and run FSAA for the full screen, the overhead would be awful. > The best way to do this is render to texture and copy the texture to > the window. This requires being able to send the scanout to memory > instead of the DAC, which seems like a feature worth having since it > gives us render to texture, which has many other uses.
You don't need to screw around with the DAC to get render to texture. As long as the texture format and framebuffer format are the same (which they will be, according to Timothy), all you need to do is reprogram the colorbuffer base address independently of the frontbuffer base address (but you need that ability anyway in order to implement double buffering). A 2x2 box filter for FSAA could then be obtained simply by using the bilinear filtering of the texture unit. cu, Nicolai
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