On Fri, Jan 8, 2016 at 6:13 PM, Rob Clark <robdcl...@gmail.com> wrote: > On Fri, Jan 8, 2016 at 5:59 PM, Ian Romanick <i...@freedesktop.org> wrote: >> On 01/08/2016 07:39 AM, Brian Paul wrote: >>> On 01/07/2016 06:29 PM, Marek Olšák wrote: >>>> Hi, >>>> >>>> This series adds the possibility for drivers to get gl_FragCoord and >>>> gl_FrontFacing as system values. When FACE is a system value, it also >>>> changes its type to integer from floating-point. >>>> >>>> Each variable has its own Const flag / Gallium CAP, so drivers can >>>> choose whether they want this for each variable. >>>> >>>> This simplifies input handling in the radeonsi driver. With this, TGSI >>>> INPUT[i] becomes fragment shader input[i] in the hardware, so the >>>> driver doesn't have to do any translation of locations. >>>> >>>> Please review. >>> >>> Looks good overall. I probably should have made fragcoord and >>> frontfacing system values from day one. We could probably migrate all >>> the drivers to that convention over time. >> >> We can probably migrate frontfacing, but I don't think we can / should >> for fragcoord. On some hardware it's not a system value, and that >> changes how we have to count the resource usage. > > although if hw treats it as a normal input, it is easier to append an > input at the end, than reshuffle to remove an input.. > > at any rate, at least for frontface, I think this would make it > slightly easier for tgsi_to_nir to spit out NIR that is more similar > to glsl_to_nir.. I don't remember, maybe I had to fixup fragcoord too > on my mesa/st glsl_to_nir branch..
The frontfacing bit of this is definitely a no-brainer. I've already pushed out a patch that makes use of it on nv50/nvc0. (Doesn't really make sense on nv30 though, where there are no native integers.) I'm a bit more hesitant about position -- I'd have to double-check the details on nv50, but I think it might count against the fp input max. (But I might be confusing it with vp position output...) However this is all à la carte, so... not a problem -- get the driver to do what's most convenient. -ilia _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
