On Wednesday 09 December 2009 10:05:13 michal wrote: > Zack Rusin pisze: > > On Wednesday 09 December 2009 08:55:09 michal wrote: > >> Zack Rusin pisze: > >>> On Wednesday 09 December 2009 08:44:20 Keith Whitwell wrote: > >>>> On Wed, 2009-12-09 at 04:41 -0800, michal wrote: > >>>>> Zack Rusin pisze: > >>>>>> Hi, > >>>>>> > >>>>>> currently Gallium3d shaders predefine all their inputs/outputs. > >>>>>> We've handled all inputs/outputs the same way. e.g. > >>>>>> VERT > >>>>>> DCL IN[0] > >>>>>> DCL OUT[0], POSITION > >>>>>> DCL OUT[1], COLOR > >>>>>> DCL CONST[0..9] > >>>>>> DCL TEMP[0..3] > >>>>>> or > >>>>>> FRAG > >>>>>> DCL IN[0], COLOR, LINEAR > >>>>>> DCL OUT[0], COLOR > >>>>>> > >>>>>> There are certain inputs/output which don't really follow the > >>>>>> typical rules for inputs/outputs though and we've been imitating > >>>>>> those with extra normal semantics (e.g. front face). > >>>>>> > >>>>>> It all falls apart a bit on anything with shader model 4.x and up. > >>>>>> That's because in there we've got what Microsoft calls system-value > >>>>>> semantics. ( > >>>>>> http://msdn.microsoft.com/en-us/library/ee418355(VS.85).aspx#System_ > >>>>>>Va l ue ). They all represent system-generated inputs/outputs for > >>>>>> shaders. And while so far we only really had to handle front-face > >>>>>> since shader model 4.x we have to deal with lots of them (geometry > >>>>>> shaders, domain shaders, computer shaders... they all have system > >>>>>> generated inputs/outputs) > >>>>>> > >>>>>> I'm thinking of adding something similar to what D3D does to > >>>>>> Gallium3d. So just adding a new DCL type, e.g. DCL_SV which takes > >>>>>> the vector name and the system-value semantic as its inputs, so FRAG > >>>>>> DCL IN[0], COLOR, LINEAR > >>>>>> DCL IN[1], COLOR[1], LINEAR > >>>>>> DCL IN[2], FACE, CONSTANT > >>>>>> would become > >>>>>> FRAG > >>>>>> DCL IN[0], COLOR, LINEAR > >>>>>> DCL IN[1], COLOR[1], LINEAR > >>>>>> DCL_SV IN[2], FACE > >>>>>> > >>>>>> It likely could be done in a more generic fashion though. Opinions? > >>>>> > >>>>> Zack, > >>>>> > >>>>> What would be the difference between > >>>>> > >>>>> DCL IN[2], FACE, CONSTANT > >>>>> > >>>>> and > >>>>> > >>>>> DCL_SV IN[2], FACE > >>>>> > >>>>> then? Maybe the example is bad, but I don't see what DCL_SV would > >>>>> give us the existing DCL doesn't. > >>>> > >>>> I'd have proposed something slightly different where the SV values > >>>> don't land in the INPUT file but some new register file. > >>>> > >>>> The reason is that when we start looking at geometry shaders, the > >>>> INPUT register file becomes two-dimensional, but these SV values > >>>> remain single-dimensional. That means that for current TGSI we'd have > >>>> stuff like: > >>>> > >>>> DCL IN[0..3][0] POSITION > >>>> DCL IN[0..3][1] COLOR > >>>> DCL IN[2] SOME_SYSTEM_VALUE > >>>> > >>>> Which is pretty nasty - half of the input file is one dimensional, > >>>> half two-dimensional, and you need to look at the index of the first > >>>> dimension to figure out whether the input reg is legal or not. > >>>> > >>>> So, I'm think some new register file to handle these system-generated > >>>> values is one possiblility, as in: > >>>> > >>>> DCL SV[0], FACE > >>>> > >>>> or > >>>> > >>>> DCL SV[1], PRIMITIVE_ID > >>>> > >>>> Thoughts? > >>> > >>> Yea, I like that. > >>> > >>> And then separate syntax to handle the properties or overloading DCL? > >>> i.e. DCL GS_INFO PRIM_IN TRIANGLES > >>> vs > >>> PROPERTY GS_INFO PRIM_IN TRIANGLES > >>> ? > >> > >> I think a geometry shader should have its own GS_INFO token that would > >> convey the information it needs, i.e. no overloading of the DCL token. > >> > >> GS_INFO PRIM_IN TRIANGLES > >> GS_INFO PRIM_OUT TRIANGLE_STRIP > >> GS_INFO MAX_VERTEX_COUNT 3 /* vertices_out for gl */ > > > > We'll be adding more of those then. Basically we'll need an extra token > > for every shader we have. > > > > COMPUTE_INFO WORK_GROUP_SIZE 4 4 4 /*x, y, z*/ > > DS_INFO DOMAIN 3 /*domain shader*/ > > HS_INFO MAXTESSFACTOR 3 /*hull shader*/ > > FS_INFO EARLYDEPTSTENCIL 1 > > etc. > > > > To me it looks uglier than a special decleration token that could handle > > all of them. > > Can you propose a patch against p_shader_tokens.h that introduces a > PROPERTY token?
I could do that but only if we agree it's in the name of love. So is everyone ok with a new register SV for system generated values and new declaration token called PROPERTY for shader specific properties (btw, d3d calls those attributes, but since attributes already have a meaning in glsl I think it'd probably wise to not try to redefine it). z ------------------------------------------------------------------------------ Return on Information: Google Enterprise Search pays you back Get the facts. http://p.sf.net/sfu/google-dev2dev _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
