This patch series implements a new GL extension, EXT_shader_samples_identical. This extension allows shaders to determine when all of the samples in a particular texel are the same. This takes advantage of the way compressed multisample surfaces are stored on modern Intel and AMD hardware. This enables optimizations in application multisample resolve filters, etc.
I really wanted to get this in the next Mesa release. For some reason, I thought the branch point was after Thanksgiving (which is next Thursday). Ken reminded me yesterday that the branch point is actually this Friday. :( As a result, I'm sending it out today to get review as soon as possible. I also wanted to get as much time as possible for other drivers to get implementations. I worked with Graham Sellers on this extension, and he assures me that the implementation on modern Radeons is trivial. My expectation is that it should be about the same as the Intel implementation. There will be some extra TGSI bits needed, but that should also be trivial. For the NIR and i965 backend bits, I mostly copied and blended the implementations of txf_ms and query_samples. There are currently only trivial piglit tests, but I am working on more. I basically hacked up tests/spec/arb_texture_multisample/texelfetch.c to use the extension to render different colors based on whether textureSamplesIdenticalEXT returned true or false. The resulting image and the generated assembly look good. My plan is to get a set of real tests out by midday tomorrow. As soon as we're confident that the spec is good, I'll submit it to Khronos for publication in the registry. I'm still waiting on feedback from another closed-source driver writer. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
