[Mesa-dev] [PATCH v2 2/5] gallium: Add new PIPE_CAP_MULTISAMPLED_RENDER_TO_TEXTURE

[Rob Clark]

I guess as long as it is just a single draw, it works out to the same
thing.  Maybe to expose the GCN functionality we could do something
like

  PIPE_CAP_SURFACE_SAMPLE_COUNT:
    0 - unsupported
    1 - msaa per draw
    2 - msaa per renderpass

??

BR,
-R

On Fri, Nov 30, 2018 at 3:41 PM Marek Olšák <maraeo at gmail.com> wrote:
>
> GCN calls it overrasterization multisampling, but it's really only useful for polygon smoothing, because there is no temporary buffer.
>
> Marek
>
> On Fri, Nov 30, 2018 at 3:35 PM Rob Clark <robdclark at gmail.com> wrote:
>>
>> On Fri, Nov 30, 2018 at 3:25 PM Marek Olšák <maraeo at gmail.com> wrote:
>> >
>> > Suggestions:
>> > - PIPE_CAP_TILED_BASED_MSAA_OVERSAMPLING
>> > - pipe_surface::tile_based_oversample_count
>> >
>> > I'm assuming this feature isn't possible without tile-based rendering.
>>
>> I guess technically an IMR could do it, with an internal temporary
>> buffer not visible to the state-tracker.  (Not sure I could come up
>> with a reason *why* you'd want to do that, but...)
>>
>> BR,
>> -R
>>
>> >
>> > Marek
>> >
>> > On Fri, Nov 30, 2018 at 1:23 PM Kristian Høgsberg <hoegsberg at gmail.com> wrote:
>> >>
>> >> On Fri, Nov 30, 2018 at 10:17 AM Marek Olšák <maraeo at gmail.com> wrote:
>> >> >
>> >> > On Fri, Nov 30, 2018 at 1:13 PM Kristian Høgsberg <hoegsberg at gmail.com> wrote:
>> >> >>
>> >> >> On Fri, Nov 16, 2018 at 7:48 PM Marek Olšák <maraeo at gmail.com> wrote:
>> >> >> >
>> >> >> > I think the name PIPE_CAP_MULTISAMPLED_RENDER_TO_TEXTURE is slightly misleading, because it doesn't imply anything about the OpenGL ES behavior, which is that a texture is multisampled in the cache, but single-sampled in memory. This should be mentioned somewhere.
>> >> >>
>> >> >> Not sure exactly which change you're recommending, but in retrospect,
>> >> >> I think it would be better to name the cap in term of how it changes
>> >> >> the gallium API instead of the GLES extension it enables. How about
>> >> >> PIPE_CAP_SURFACE_SAMPLE_COUNT, to indicate that it allows overriding
>> >> >> sample counts in pipe_surface?
>> >> >
>> >> >
>> >> > That's an interesting idea, but how does it convey that multisampled surfaces are never multisampled in memory?
>> >>
>> >> How are you going to convey all that in a cap enum name? In general,
>> >> the cap names are concise hints and not super descriptive - you have
>> >> to go read the documentation to understand the semantics.
>> >>
>> >> Do you have a specific name you'd like to see or can we go with
>> >> PIPE_CAP_SURFACE_SAMPLE_COUNT?
>> >>
>> >> >
>> >> > Marek
>> >
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