On 17.06.2008 18:44, Ian Romanick wrote: > Nicolai Hähnle wrote: > >> 2. We want to rewrite TEX instructions in fragment programs *before* other >> transformations; however for shadow textures, the resulting code depends on >> the compare function of the referenced texture. > > This may not be true. How does your hardware work (I don't know which > driver you're working on )? Does it use state set in the texture > hardware to select shadow sampling or does it use special instructions > for shadow sampling? The GLSL spec says that if the sampler state is > ignored. It also says that the results are "undefined" if the texture > state (i.e., internal format) doesn't match a shadow mode. You can > probably just generate the shadow texture instructions and let the user > shoot themselves in the foot.
Well, the title suggests r300 :-). IIRC there's no hardware support at all. You simply do a point-sampled texture lookup (or you could do 4 point-sampled lookups to get PCF later), then do the shadow comparison in the shader. So the generated fragment shader code will indeed be different for different shadow comparison modes... Roland ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
