[Mesa-dev] [PATCH] gallium: add st_api feature mask to prevent advertising MS visuals

[Brian Paul]

On 05/22/2012 09:58 AM, Brian Paul wrote:
> On 05/22/2012 08:37 AM, Christoph Bumiller wrote:
>> On 05/22/2012 04:23 PM, Brian Paul wrote:
>>> On 05/21/2012 03:46 PM, Christoph Bumiller wrote:
>>>> ---
>>>> src/gallium/include/state_tracker/st_api.h | 16 +++++++++++++
>>>> src/gallium/state_trackers/dri/common/dri_screen.c | 23
>>>> +++++++++++--------
>>>> src/gallium/state_trackers/vega/vg_manager.c | 1 +
>>>> src/mesa/state_tracker/st_manager.c | 1 +
>>>> 4 files changed, 31 insertions(+), 10 deletions(-)
>>>
>>> Hi Christopher, could you give a bit more background on this? I'm not
>>> sure I understand the problem you're trying to solve here.
>>>
>>
>> If gallium drivers advertise support for multisampled surfaces via
>> is_format_supported (so EXT_framebuffer_multisample works properly),
>> the
>> dri state tracker sees that and advertises multisample visuals. But
>> since they aren't actually implemented, applications that try to use
>> them will crash or worse.
>
> So the driver supports MS user FBOs/Renderbuffer but not MS
> windows/pbuffers? What would it take to fully support MS visuals? Is
> it just a driver issue or is there some DRI/infrastructure that's
> missing?
>
>
>>> Where does 8 come from? The old value, below, was 4. I don't know
>>> > where that came from either.
>>> >
>> The old value was 8 as well (i * 2 -> i), it's the maximum number of
>> samples any current hardware supports.
>
> There should be a comment for that then. And, we should probably use a
> #define MAX_SAMPLES instead of '8'. There's also a few arrays in that
> function which should be fixed:
>
> uint8_t depth_bits_array[5];
> uint8_t stencil_bits_array[5];
> uint8_t msaa_samples_array[5];
>
> to be:
>
> uint8_t depth_bits_array[MAX_SAMPLES];
> uint8_t stencil_bits_array[MAX_SAMPLES];
> uint8_t msaa_samples_array[MAX_SAMPLES];
>
> BTW, doesn't NVIDIA have a 5-sample MS mode? Maybe the loop should
> also just try odd numbers of samples.

"should also try odd numbers"

-Brian