Keith Whitwell wrote on 2010-03-11 14:21: > On Thu, 2010-03-11 at 03:16 -0800, michal wrote: > >> Hi, >> >> I would like to merge the branch in subject this week. This feature >> branch allows state trackers to bind sampler views instead of textures >> to shader stages. >> >> A sampler view object holds a reference to a texture and also overrides >> internal texture format (resource casting) and specifies RGBA swizzle >> (needed for GL_EXT_texture_swizzle extension). >> > > Michal, > > I've got some issues with the way the sampler views are being generated > and used inside the CSO module. > > The point of a sampler view is that it gives the driver an opportunity > to do expensive operations required for special sampling modes (which > may include copying surface data if hardware is deficient in some way). > > This approach works if a sampler view is created once, then used > multiple times before being deleted. > > Unfortunately, it seems the changes to support this in the CSO module > provide only a single-shot usage model. Sampler views are created in > cso_set_XXX_sampler_textures, bound to the context, and then > dereferenced/destroyed on the next bind. > > The reason CSO code looks like this is because it was meant to be an itermediate step towards migration to sampler view model. Fully converting all existing state trackers is non-trivial and thus I chose this conservative approach. State trackers that do not care about extra features a sampler view provides will keep using this one-shot CSO interface with the hope that creation of sampler objects is lighweight (format matches texture format, swizzle matches native texel layout, etc.). Ideally, everybody moves on and we stop using CSO for sampler views. I prefer putting my effort into incremental migration of state trackers rather than caching something that by definition doesn't need to be cached.
Thanks for having a look. > To make this change worthwhile, we'd want to somehow cache sampler views > and reuse them on multiple draws. Currently drivers that implement > views internally hang them off the relevant texture. > > The choices in this branch are to do it in the CSO module, or push it up > to the state tracker. > > ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
