[Mesa-dev] [PATCH] glsl: do not set the 'smooth' qualifier by default on ES shaders

[Nicolai Hähnle]

On 11.09.2017 16:47, Ilia Mirkin wrote:
> On Mon, Sep 11, 2017 at 10:44 AM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
>> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>>
>> It breaks integer inputs and outputs on vertex processing stages
>> (e.g. geometry stages). Instead, rely on the driver to choose
>> smooth interpolation by default.
>> ---
>>
>> How about this instead? I haven't fully thought it through, but
>> that's where the INTERP_MODE_SMOOTH is coming from.
>>
>> To be honest I'm not 100% sure about what INTERP_MODE_NONE can
>> mean, but I think it's definitely better than removing the (very
>> valid!) assertion in the packing code.
> 
> I couldn't understand what that assertion was asserting, esp in the
> presence of struct in/out variables.

structs can't have per-member interpolation qualifiers. So a struct that 
contains integer values must have FLAT or NONE interpolation as a whole.

That clashes pretty hard with that ES rule, though ("When no 
interpolation qualifier is present, smooth interpolation is used.").

On second thought, that assertion is actually irrelevant for varying 
packing itself, but it's still pretty disturbing that it's broken by 
this particular shader.

Cheers,
Nicolai


> 
>>
>> ---
>>   src/compiler/glsl/ast_to_hir.cpp | 11 -----------
>>   1 file changed, 11 deletions(-)
>>
>> diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
>> index 98d2f94e129..cb42041642d 100644
>> --- a/src/compiler/glsl/ast_to_hir.cpp
>> +++ b/src/compiler/glsl/ast_to_hir.cpp
>> @@ -3119,31 +3119,20 @@ interpret_interpolation_qualifier(const struct ast_type_qualifier *qual,
>>                                     struct _mesa_glsl_parse_state *state,
>>                                     YYLTYPE *loc)
>>   {
>>      glsl_interp_mode interpolation;
>>      if (qual->flags.q.flat)
>>         interpolation = INTERP_MODE_FLAT;
>>      else if (qual->flags.q.noperspective)
>>         interpolation = INTERP_MODE_NOPERSPECTIVE;
>>      else if (qual->flags.q.smooth)
>>         interpolation = INTERP_MODE_SMOOTH;
>> -   else if (state->es_shader &&
>> -            ((mode == ir_var_shader_in &&
>> -              state->stage != MESA_SHADER_VERTEX) ||
>> -             (mode == ir_var_shader_out &&
>> -              state->stage != MESA_SHADER_FRAGMENT)))
>> -      /* Section 4.3.9 (Interpolation) of the GLSL ES 3.00 spec says:
>> -       *
>> -       *    "When no interpolation qualifier is present, smooth interpolation
>> -       *    is used."
>> -       */
>> -      interpolation = INTERP_MODE_SMOOTH;
>>      else
>>         interpolation = INTERP_MODE_NONE;
>>
>>      validate_interpolation_qualifier(state, loc,
>>                                       interpolation,
>>                                       qual, var_type, mode);
>>
>>      return interpolation;
>>   }
>>
>> --
>> 2.11.0
>>
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>> mesa-dev at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev


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