Comment 2 for bug 1400580

It's trivial to do in a fragment shader:
   gl_FragColor = vec4(1.0 - red, 1.0 - green, 1.0 - blue, 1.0);

The only issue is that Unity doesn't share shader logic with Mir. We'd have to implement it in Unity8/Qt at least.

I'll leave the Mir task open because we might get a separate proof of concept done in Mir still.