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

[Bryan Cain]

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.