[Mesa-dev] [PATCH] nv50: implement multisample textures

[Christoph Bumiller]

On 25.10.2013 23:51, Bryan Cain wrote:
> On 10/25/2013 04:11 PM, Christoph Bumiller wrote:
>> On 25.10.2013 20:35, Emil Velikov wrote:
>>> On 21/10/13 23:23, Bryan Cain wrote:
>>>> This is a port of 4da54c91d24da ("nvc0: implement multisample textures") to
>>>> nv50.
>>>>
>>>> When coupled with the patch to only report 16 texture samplers (to fix
>>>> crashes), all of the Piglit tests in spec/arb_texture_multisample pass.
>>>>
>>> Hello Bryan,
>>>
>>> Big thanks for your work. As promised here is a quick piglit summary on
>>> my nv96
>>>
>>> pass/fail/crash
>>> 69/32/27
>>>
>>> * dmesg does not spit anything nouveau related during the tests
>>> * any geometry shader related tests were skipped
>>> (piglit: info: Failed to create GL 3.2 core context)
>>> * all the crashes are due to the following assert
>>> codegen/nv50_ir_emit_nv50.cpp:1393:emitTEX: Assertion `argc <= 4' failed.
>> I'm not sure how you'd get > 4 arguments there (x y layer sample ?).
>> There's no mip maps for multisample textures.
>>
>> But either way you're probably going to have to do things by hand:
>> E.g. MS8 textures contain contiguous 4x2 rectangles of samples for each
>> pixel, so you multiply x by 4 and y by 2 to arrive at the sub-rectangle
>> and then add the correct offsets for the sample id as seen in
>> get_sample_position (store the info in a constant buffer, that has to be
>> updated when texture changes).
>>
>> You might want to use a lookup table like in nve4 compute (look for "MS
>> sample coordinate offsets") to map sample id to coordinate offset, that
>> one works for any sample count as long as you don't use the ALT modes
>> (nve4 doesn't need to for textures, but for images/surfaces/UAVs/RATs
>> where the whole VM address calculation is done by hand).
> You're probably right.  I don't know why MSAA appears to work for me,
> but there's probably something wrong with the output that I haven't
> noticed.  I'll work on implementing it properly this weekend.

MSAA itself (rendering and resolving) has been working before, the only
thing that ARB_texture_multisample adds is texelFetch from MS resources.