Roland Scheidegger wrote: > On 18.05.2009 12:55, Keith Whitwell wrote: >> It's very easy for a driver to get smooth lines & points, line stipple, >> unfilled polygons, etc, working under gallium -- basically just fall >> back to software t&l and the draw module will do them for you. >> >> They are still hardware-rasterized, but we need to do >> software-transformation to tweak the geometry to cover the bounding area >> of the primitive. Then we set a special 'smoothing' fragment shader and >> pass the primitives back into the driver. >> >> As long as you already support switching between hwtnl and swtnl (or >> just swtnl all the time) this is very easy for the driver. > Yes, though some hardware doesn't require software t&l for this but can > do that somehow, however need some handwaving. For instance radeon r300 > hardware (I assumed this was what Corbin was refering to) has GA_LINE_S0 > reg with description "S texture coordinate value generated for vertex 0 > of an antialiased line; 32-bit IEEE float format. Typical 0.0.". Not > sure how it's supposed to work however, the coord generation looks like > "line sprite" to me... i965 can do coverage value calculation and so I > think wouldn't need sw tnl neither.
That's the idea. My technique is actually along the lines of "Ooh, this register looks interesting, I'll bug Alex until he tells me what it does." Tends to work out very well. :3 r300 is special in that only the actual PVS (vert shader engine) and UCP (user clipping) are missing from SW TCL chipsets; the viewport transform, vert fetcher, texgen/primitive stuffing, etc. are all still present and usable. Anyway, I think I've learned enough to be able to implement the rest of rasterizer state. I've got plenty of bugs elsewhere, like the entire r3xx fragment shader setup, so I'm not needing extra stuff, but I've always wondered about those flags. Thanks! ~ C. ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
