gistfile1.txt

struct InnerVertexOut {
    float4 extra : attribute(0);
}

Struct VertexOut {
    float4 position : SV_Position;
    InnerVertexOut innerVertexOut;
}

struct VertexInput {
    float something : attribute(0);
}

vertex VertexOut vertexShader(VertexInput vertexInput, float somethingElse : attribute(1)) { ... }



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struct MetalStageInParameters {
    float metalSomething [[ attribute(0) ]];
    float metalSomethingElse [[ attribute(1) ]];
};

struct MetalVertexOut {
    float4 metalPosition [[ position ]];
    float4 metalExtra [[ user(user0) ]];
};

vertex MetalVertexOut metalVertexShader(MetalStageInParameters metalStageInParameters) {
    VertexInput vertexInput;
    float somethingElse;
    vertexInput.something = metalStageInParameters.metalSomething;
    somethingElse = metalStageInParameters.metalSomethingElse;

    ...

    /* "return foo" gets turned into */
    metalVertexOut metalVertexOut;
    metalVertexOut.metalPosition = foo.position;
    metalVertexOut.metalExtra = foo.innerVertexOut.extra;
    return metalVertexOut;
}