On Monday, August 04, 2014 08:17:13 PM Ian Romanick wrote: > On 08/03/2014 11:07 PM, Kenneth Graunke wrote: > > On Sunday, June 22, 2014 03:59:01 AM Marek Olšák wrote: > >> That's right. A uniform won't work with ARB_draw_indirect unless > >> you lower it to direct draws, which would be very bad if it was > >> applied to all drivers. > >> > >> Radeonsi indeed supports BaseVertex and BaseInstance as system > >> values in the vertex shader. Well, vertex fetching has to be done > >> in the vertex shader on that hardware, so the system values are > >> kinda required there. > >> > >> Marek > > > > FWIW, I've thrown together some patches for i965 which make > > gl_BaseVertex available as a system value, which I think is the right > > thing to do. I've tested the indirect draw case, and it seems to > > work fine. > > Yeah, I like your approach. Patch 12 in my original series causes > regressions in a couple piglit tests... which I somehow did not see > before. It looks like your series regressions some geometry shader > tests. glsl-1.50-geometry-primitive-types looks like the geometry > shader is getting a floating point value for the vertex ID: > > Testing GL_LINES(1 vertices) > Testing GL_LINES(2 vertices) > Expected vertex IDs: 1 2 > Actual vertex IDs: -1082130431 1065353218 > Testing GL_LINES(3 vertices) > Expected vertex IDs: 1 2 > Actual vertex IDs: -1082130431 1065353218 > Testing GL_LINES(4 vertices) > Expected vertex IDs: 1 2 3 4 > Actual vertex IDs: -1082130431 1065353218 1065353219 -1082130428 > > -1082130431 is 0xbf800001, which is the bit encoding of -1.0. > 1065353218 is the bit encoding of 1.0. So... there's something fishy > there. :)
Whoops. I believe I've fixed this in my 'basevertex-v6.1' branch. I wasn't emitting the 3DSTATE_VERTEX_BUFFERS for the buffer containing gl_BaseVertex unless there were other vertex buffers as well. Somehow, you ended up with -1.0...I got more rubbish looking values. > I did some clean up on the branch and pushed it to basevertex-v6. I > squashed your HAX commit into the original commit for the lowering pass, > and I removed the commit that added the fake uniform. Looks good! One nit...I noticed that the lowering flag is still called gl_VertexID_using_uniform_gl_BaseVertex. Personally, I would just drop the enum and use a bool for whether to add gl_BaseVertex to gl_VertexID. It sounds like the system value is what most people want, and if someone wants a uniform path, they can extend it in the future. > I think your approach will allow us to implement most of > GL_ARB_shader_draw_parameters without much difficulty. We'll get > gl_BaseVertex and gl_BaseInstance... gl_DrawID seems a bit harder. Yeah :) Perhaps I should call it draw_parameters_bo instead of basevertex_bo.
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