On Thu, Apr 30, 2015 at 5:56 PM, Chris Forbes <[email protected]> wrote:
>> /* Only ARB_texture_gather but not GLSL 4.0 or ARB_gpu_shader5.
>> * used for relaxation of const offset requirements.
>> */
>> static bool
>> -texture_gather_only(const _mesa_glsl_parse_state *state)
>> +texture_gather_only_or_es31(const _mesa_glsl_parse_state *state)
>> {
>> return !state->is_version(400, 0) &&
>> !state->ARB_gpu_shader5_enable &&
>> - state->ARB_texture_gather_enable;
>> + (state->ARB_texture_gather_enable ||
>> + state->is_version(0, 310));
>> }
>
> I don't think this is correct. This is used to enable the restricted
> versions of textureGather/textureGatherOffset which require a constant
> offset. This restriction doesn't appear to exist in ES3.1 -- it's more
> or less the GS5 version.
>
> An example pair, where at most one should be enabled:
> _texture(ir_tg4, texture_gather_only, glsl_type::vec4_type,
> glsl_type::sampler2D_type, glsl_type::vec2_type, TEX_OFFSET),
> _texture(ir_tg4, gpu_shader5, glsl_type::vec4_type,
> glsl_type::sampler2D_type, glsl_type::vec2_type, TEX_OFFSET_NONCONST),
From my read of GLSL ES 3.10, it requires const offsets. Non-const
support is added in EXT_gpu_shader5:
* extending the textureGather() built-in functions provided by
OpenGL ES Shading Language 3.10:
* allowing shaders to use arbitrary offsets computed at run-time to
select a 2x2 footprint to gather from; and
-ilia
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