resources/sksl/compute/DesaturateFunction.compute

layout(binding=0) in texture2D src;
layout(binding=1) out texture2D dest;

// TODO(skia:13609): we need a mechanism for access levels on src and dst.
noinline void desaturate(texture2D src, texture2D dest, half4 color) {
    color.rgb = half3(dot(color.rgb, half3(0.22, 0.67, 0.11)));
    write(dest, sk_ThreadPosition.xy, read(src, sk_ThreadPosition.xy));
}

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