[Mesa-dev] [PATCH] radv: fix centroid interpolation

[Bas Nieuwenhuizen]

On Mon, May 21, 2018 at 2:37 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
> What do centroid / sample interpolation modes mean in a non-msaa
> environment? Or does key.fs.multisample mean something else?

Yeah that was what I was wondering too. It is valid for shaders to use
so we should handel it, but I suspect under normal operations we have
centroid=center.  I'm still not sure how this would interact with e.g.
VK_EXT_sample_locations if you set the single sample to a non-center
location though, which would be the interesting corner case.


>
> On Mon, May 21, 2018 at 5:15 AM, Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
>> It's legal to set the centroid and sample interpolation modes
>> when MSAA disabled. So, we have to initialize the centroid
>> inputs because the hardware doesn't.
>>
>> This fixes rendering issues with DXVK and The Witness, World of
>> Warcraft, Trackmania and probably more games.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106315
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102390
>> CC: 18.0 18.1 <mesa-stable at lists.freedesktop.org>
>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>> ---
>>  src/amd/vulkan/radv_nir_to_llvm.c | 3 ---
>>  1 file changed, 3 deletions(-)
>>
>> diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
>> index 9b9619b877e..2d91ded7fe5 100644
>> --- a/src/amd/vulkan/radv_nir_to_llvm.c
>> +++ b/src/amd/vulkan/radv_nir_to_llvm.c
>> @@ -2075,9 +2075,6 @@ static void
>>  prepare_interp_optimize(struct radv_shader_context *ctx,
>>                          struct nir_shader *nir)
>>  {
>> -       if (!ctx->options->key.fs.multisample)
>> -               return;
>> -
>>         bool uses_center = false;
>>         bool uses_centroid = false;
>>         nir_foreach_variable(variable, &nir->inputs) {
>> --
>> 2.17.0
>>
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