On 14 August 2013 11:46, Anuj Phogat <anuj.pho...@gmail.com> wrote: > On Wed, Aug 14, 2013 at 10:25 AM, Paul Berry <stereotype...@gmail.com> > wrote: > > On 9 August 2013 19:01, Anuj Phogat <anuj.pho...@gmail.com> wrote: > >> - src.brw_surfaceformat = dst.brw_surfaceformat; > >> + if (src.num_samples > 1) > >> + src.brw_surfaceformat = dst.brw_surfaceformat; > >> + else > >> + dst.brw_surfaceformat = src.brw_surfaceformat; > > > > > > I thought we decided that it was a bug to ever set src.brw_surfaceformat > = > > dst.brw_surfaceformat, and we should do dst.brw_surfaceformat = > > src.brw_surfaceformat always. Am I remembering wrong? > As suggested by Ian, I modified a piglit test and checked the > behavior on proprietary NVIDIA OpenGL 4.3 drivers. NVIDIA > still uses destination format to decide the type of averaging > during resolve. During our offline discussion you mentioned > how NVIDIA's approach produce slightly better looking images > as compared to using the source buffer format for avearging the > samples. Also, OpenGL specification doesn't seem to be strict > about it. So, I decided to use an if-else to take care of averaging > format in single sample scaled blits. I don't have any strong > opinions about it and I'm willing to post a patch to use > dst.brw_surfaceformat = src.brw_surfaceformat for all cases. > Please let me know if you're in favor of fixing it. >
Ah, ok. In that case I think you made the right decision. Would you mind putting a comment above the if statement documenting your reasoning? It's a really subtle decision and I'd hate for someone to come along in the future and try to "fix" it without understanding the history. Thanks!
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