Keith Whitwell wrote on 2010-02-12 14:28: > On Fri, 2010-02-12 at 05:09 -0800, michal wrote: > >> Keith Whitwell wrote on 2010-02-12 13:39: >> >>> On Fri, 2010-02-12 at 04:32 -0800, Micha?? Kr??l wrote: >>> >>> >>>> Module: Mesa >>>> Branch: master >>>> Commit: aa0b671422880b99dc178d43d1e4e1a3f766bf7f >>>> URL: >>>> http://cgit.freedesktop.org/mesa/mesa/commit/?id=aa0b671422880b99dc178d43d1e4e1a3f766bf7f >>>> >>>> Author: Michal Krol <mic...@vmware.com> >>>> Date: Fri Feb 12 13:32:35 2010 +0100 >>>> >>>> util: Fix descriptors for R32_FLOAT and R32G32_FLOAT formats. >>>> >>>> >>> Michal, >>> >>> Is this more like two different users expecting two different results in >>> those unused columns? >>> >>> In particular, we definitely require the missing elements to be extended >>> to (0,0,0,1) when fetching vertex data, and probably also in OpenGL >>> texture sampling (if we supported these formats for that). >>> >>> >>> >> Gallium should follow D3D rules, so I've been following D3D here. Also, >> util_unpack_color_ub() in u_pack_color.h already sets the remaining >> fields to 0xff. >> >> Note that D3D doesn't have the problem with expanding vertex attribute >> data since you can't have X or XY vertex positions, only XYZ (with W >> extended to 1 as in GL) and XYZW. >> > > But surely D3D permits two-component texture coordinates, which would be > PIPE_FORMAT_R32G32_FLOAT, and expanded as (r,g,0,1)... > > >>> Brian added a table of differences between GL and other APIs recently to >>> gallium/docs - does your change agree with that? >>> >>> >>> >> Where's that exactly, I can't find it? >> > > It seems like we'd want to be able to support both usages - the > alternative in texture sampling would be forcing the state tracker to > generate varients of the shader when 2-component textures are bound. I > would say that's an unreasonable requirement on the state tracker. > > It seems like in GL would want (0,0,0,1) expansion everywhere, but D3D > would want differing expansions in different parts of the pipeline. > That indicates a single flag in the context somewhere isn't sufficient > to choose between the two. > > Maybe there need to be two versions of these PIPE_FORMAT_ enums to > capture the different values in the missing components? > > EG: > > PIPE_FORMAT_R32G32_0001_FLOAT > PIPE_FORMAT_R32G32_1111_FLOAT > > ? or something along those lines?? > >
You are right. Alternatively, follow the more sane API (GL apparently), assume 0001 as default and use the 1111 infix to override. ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
