[Mesa-dev] [PATCH 4/8] glsl: Add new builtins required by GL_ARB_sample_shading

[Kenneth Graunke]

On 10/15/2013 10:02 AM, Ian Romanick wrote:
> On 10/14/2013 10:12 AM, Anuj Phogat wrote:
>> New builtins added by GL_ARB_sample_shading:
>> in vec2 gl_SamplePosition
>> in int gl_SampleID
>> in int gl_NumSamples
>> out int gl_SampleMask[]
>>
>> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
>> ---
>>  src/glsl/builtin_variables.cpp | 11 +++++++++++
>>  src/glsl/link_varyings.cpp     |  2 ++
>>  src/mesa/main/mtypes.h         |  7 ++++++-
>>  src/mesa/program/prog_print.c  |  5 +++++
>>  4 files changed, 24 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/glsl/builtin_variables.cpp b/src/glsl/builtin_variables.cpp
>> index ae0a03f..c886840 100644
>> --- a/src/glsl/builtin_variables.cpp
>> +++ b/src/glsl/builtin_variables.cpp
>> @@ -30,6 +30,9 @@
>>  #include "program/prog_statevars.h"
>>  #include "program/prog_instruction.h"
>>  
>> +static struct gl_builtin_uniform_element gl_NumSamples_elements[] = {
>> +   {NULL, {STATE_NUM_SAMPLES, 0, 0}, SWIZZLE_XYZW}
>> +};
>>  
>>  static struct gl_builtin_uniform_element gl_DepthRange_elements[] = {
>>     {"near", {STATE_DEPTH_RANGE, 0, 0}, SWIZZLE_XXXX},
>> @@ -236,6 +239,7 @@ static struct gl_builtin_uniform_element gl_NormalMatrix_elements[] = {
>>  #define STATEVAR(name) {#name, name ## _elements, Elements(name ## _elements)}
>>  
>>  static const struct gl_builtin_uniform_desc _mesa_builtin_uniform_desc[] = {
>> +   STATEVAR(gl_NumSamples),
>>     STATEVAR(gl_DepthRange),
>>     STATEVAR(gl_ClipPlane),
>>     STATEVAR(gl_Point),
>> @@ -613,6 +617,7 @@ builtin_variable_generator::generate_constants()
>>  void
>>  builtin_variable_generator::generate_uniforms()
>>  {
>> +   add_uniform(int_t, "gl_NumSamples");
>>     add_uniform(type("gl_DepthRangeParameters"), "gl_DepthRange");
>>     add_uniform(array(vec4_t, VERT_ATTRIB_MAX), "gl_CurrentAttribVertMESA");
>>     add_uniform(array(vec4_t, VARYING_SLOT_MAX), "gl_CurrentAttribFragMESA");
>> @@ -789,6 +794,12 @@ builtin_variable_generator::generate_fs_special_vars()
>>        if (state->AMD_shader_stencil_export_warn)
>>           var->warn_extension = "GL_AMD_shader_stencil_export";
>>     }
>> +
>> +   if (state->ARB_sample_shading_enable) {
>> +      add_input(VARYING_SLOT_SAMPLE_ID, int_t, "gl_SampleID");
>> +      add_input(VARYING_SLOT_SAMPLE_POS, vec2_t, "gl_SamplePosition");
>> +      add_output(FRAG_RESULT_SAMPLE_MASK, array(int_t, 1), "gl_SampleMask");
> 
> I don't see code anywhere in this patch series that correctly sizes this
> array.  I thought gl_SampleMask.length() == gl_NumSamples... except you
> can't use .length() on gl_SampleMask because the size can't be known at
> compile-time.  We should have a test that 'gl_SampleMask.length()' fails
> to compile. :)
> 
> The only other array that works like this is gl_TexCoord.  That array is
> sized to 0 (line 837 of builtin_variables.cpp).  I believe gl_SampleMask
> should do the same.

I believe 1 is the correct size.  See my reply for a spec quote.

--Ken