resources/sksl/compute/DesaturateFunction.compute

layout(binding=0) readonly texture2D src;
layout(binding=1) writeonly texture2D dest;

noinline void desaturate(readonlyTexture2D src, writeonlyTexture2D dest) {
    half4 color = read(src, sk_GlobalInvocationID.xy);
    color.rgb = half3(dot(color.rgb, half3(0.22, 0.67, 0.11)));
    write(dest, sk_GlobalInvocationID.xy, color);
}

void main() {
    if (sk_GlobalInvocationID.x < width(src) && sk_GlobalInvocationID.y < height(src)) {
        desaturate(src, dest);
    }
}