Patches 5..10 Reviewed-by: Tapani Pälli <tapani.pa...@intel.com>
Also tested that these fix the new Piglit tests and esconform3 test. I made a little proposal for patch 10 but not sure if this change would be worth the trouble. On 06/21/2014 04:00 AM, Ian Romanick wrote: > This patch series fixes bugs in the i965 w.r.t. several uses of > gl_VertexID. OpenGL (desktop and ES) have the following expectations of > gl_VertexID: > > 1. When used with BaseVertex drawing commands, gl_VertexID will include > the value of basevertex. This differens from "the other API," but the > change in OpenGL was based on feedback from application developers. > This only affects OpenGL 3.2+. > > 2. When used with DrawArrays drawing commands, gl_VertexID will count > from the 'start' value instead of zero. This affects OpenGL 3.0+ and > OpenGL ES 3.0+. > > The i965 driver botched both of these for slightly different reasons. > For #1, our hardware was designed with the "other API's" semantic in > mind, so gl_VertexID doesn't include the basevertex value. > > For #2, we implement DrawArrays with a non-zero start index by > reprogramming the array base offset. As a result, gl_VertexID always > counts from zero. > > I suspect other hardware may suffer from one or both of these issues. I > have sent tests to the piglit list to reproduce them. > > To fix both of these issues, the shader needs to know the basevertex > value. A later GL extension, GL_ARB_shader_draw_parameters, adds > gl_BaseVertex and gl_BaseInstance as built-in variables. I believe some > hardware implements these as system values much like gl_VertexID. > > I started this series with the assumption that we could have a > SYSTEM_VALUE_BASE_VERTEX that might come from a uniform. In the end, I > couldn't make that work. I left patch 7 in the series, but we may want > to remove it. > > I added a STATE_BASE_VERTEX uniform instead. > > There is now a lowering pass that converts gl_VertexID to > gl_VertexIDMESA + gl_BaseVertex (backed by a uniform). Some of these > names should probably be changed. > > I have also contemplated adding an extension that exposes the other > semantic for gl_VertexID for applications that actually want that. This > is primarily things that are porting content (or "bridging" content) > from the other API. That, however, can happen later. > > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
