domeLight.glslfx doesn't support Apple's Metal

[MrKepzie]

When using latest USD on macOS, the domeLight.glslfx compute shader fails to compile on Metal.
This is due to a few GL hard-coding in the shader which makes the shader generator fail to recognize/replace tokens, such as hd_GlobalInvocationID.

Based on other uses of HdStGLSLProgram::GetComputeProgram, seems like there's something to pass to setup the kernel parameters, including output texture

Log:

Compilation failed: 

program_source:203:2: error: invalid preprocessing directive
#version 430
 ^
program_source:208:8: error: C++ requires a type specifier for all declarations
layout(binding = 0) uniform sampler2D inTexture;
       ^
program_source:208:1: error: C++ requires a type specifier for all declarations
layout(binding = 0) uniform sampler2D inTexture;
^
program_source:208:20: error: expected ';' at end of declaration list
layout(binding = 0) uniform sampler2D inTexture;
                   ^
                   ;
program_source:209:8: error: C++ requires a type specifier for all declarations
layout(rgba16f, binding = 1) uniform image2D outTexture;
       ^
program_source:209:17: error: C++ requires a type specifier for all declarations
layout(rgba16f, binding = 1) uniform image2D outTexture;
                ^
program_source:209:1: error: C++ requires a type specifier for all declarations
layout(rgba16f, binding = 1) uniform image2D outTexture;
^
program_source:209:29: error: expected ';' at end of declaration list
layout(rgba16f, binding = 1) uniform image2D outTexture;
                            ^
                            ;
program_source:243:8: error: C++ requires a type specifier for all declarations
layout(local_size_x = 32, local_size_y = 32) in;
       ^
program_source:243:27: error: C++ requires a type specifier for all declarations
layout(local_size_x = 32, local_size_y = 32) in;
                          ^
program_source:243:1: error: C++ requires a type specifier for all declarations
layout(local_size_x = 32, local_size_y = 32) in;
^
program_source:214:30: error: use of undeclared identifier 'outTexture'
    vec2 outDims = imageSize(outTexture);
                             ^
program_source:216:33: error: implicit conversions between vector types ('int2' (vector of 2 'int' values) and 'float2' (vector of 2 'float' values)) are not permitted
    vec2 texCoords = (outCoords + vec2(0.5, 0.5)) / outDims;
                                ^
program_source:224:23: error: use of undeclared identifier 'inTexture'
    return textureLod(inTexture, coord, sampleLod).rgb;
                      ^
program_source:252:32: error: use of undeclared identifier 'inTexture'
    ivec2 inDims = textureSize(inTexture, 0);
                               ^
program_source:283:29: error: use of undeclared identifier 'gl_GlobalInvocationID'
    ivec2 outCoords = ivec2(gl_GlobalInvocationID.xy);
                            ^
program_source:289:16: error: use of undeclared identifier 'outTexture'
    imageStore(outTexture, outCoords, outColor);
               ^

[jilliene]

Filed as internal issue #USD-6970