I'd like to have some more definitive review comments on this patch (sending to Brian and Keith for this).
Right now GLSL is the *only* Gallium user that does not use sequential indexes starting from 0 for vertex shader outputs and fragment shader inputs. This causes problems for some drivers such as nv30/nv40 that don't remap the indexes right now. This can be addressed in two ways: 1. Don't require Gallium users to use sequential indices, and require vertex shader inputs and fragment shader outputs to match perfectly 2. Don't require Gallium users to use sequential indices, and change nv30/nv40 and possibly other drivers to remap indices 3. Fix the only problematic user, GLSL, to use sequential indices (1) will break the Mesa state tracker in a very hard to fix way. (2) is complex and means that nv30/nv40 and maybe other drivers can no longer compile vertex and fragment shaders independently. (3) is a simple fix, provided by this patch. I feel that (3), implemented by this patch, is the best solution, since driver simplicity is one of the Gallium design goals, and I don't see any significant advantages in supporting discontiguous vertex shader output / fragment shader input values. OpenGL and DirectX 9/10 don't seem to allow arbitrary numbers for vertex shader outputs and fragment shader inputs, and instead require 0-7, 0-15 or 0-31 depending on feature level. If this is wrong, please correct me. I propose that Gallium should also require 0-x indices and not arbitrary values. Thus, GLSL should be fixed to respect that. Note that this change cannot be done in the state tracker because it requires to see both the fragment and vertex shaders at once, which only happens in the GLSL linker. Thus, while the change has been discussed with Gallium in mind, it is done at the Mesa program level, and it actually results in Mesa programs with contiguous indices. This also potentially benefits non-Gallium drivers. What do you think? ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
