sksl/shared/StructIndexLookup.sksl

uniform half4 colorGreen, colorRed;

struct InnerLUT {
    float3 values;
};
struct OuterLUT {
    InnerLUT inner[3];
};
struct Root {
    OuterLUT outer[3];
};

half4 main(float2 coords) {
    Root data;
    data.outer[0].inner[0].values = float3(1, 10, 100);
    data.outer[0].inner[1].values = float3(2, 20, 200);
    data.outer[0].inner[2].values = float3(3, 30, 300);
    data.outer[1].inner[0].values = float3(4, 40, 400);
    data.outer[1].inner[1].values = float3(5, 50, 500);
    data.outer[1].inner[2].values = float3(6, 60, 600);
    data.outer[2].inner[0].values = float3(7, 70, 700);
    data.outer[2].inner[1].values = float3(8, 80, 800);
    data.outer[2].inner[2].values = float3(9, 90, 900);

    float3 expected = float3(0);
    for (int i=0; i<3; ++i) {
        for (int j=0; j<3; ++j) {
            expected += float3(1, 10, 100);

            // Compare the float3 as a group.
            if (data.outer[i].inner[j].values != expected) {
                return colorRed;
            }

            // Compare the float3 as individual units.
            for (int k=0; k<3; ++k) {
                if (data.outer[i].inner[j].values[k] != expected[k]) {
                    return colorRed;
                }
            }
        }
    }

    return colorGreen;
}