resources/sksl/compute/DesaturateFunction.compute

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

noinline void desaturate(readonly texture2D src, writeonly texture2D dest) {
    half4 color = read(src, sk_ThreadPosition.xy);
    color.rgb = half3(dot(color.rgb, half3(0.22, 0.67, 0.11)));
    write(dest, sk_ThreadPosition.xy, color);
}

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