Collimated gun sights?

[PRB]

Have you people seen those reflected gun sights on the A2A planes which are “focused to infinity”, or as some say “collimated?” How is this accomplished? The only way I can think of doing it would be for the gauge to detect eye-point changes in the sim, and move the gauge to “follow” the eye point. Is there another way that it's done? Because I don't see that eye point values are part of what's “exposed” from the sim to the gauge for evaluating.

[hairyspin]

Funnily enough I was thinking about how to do that recently. I don't think a gauge would be essential, the sight cross-hair could be a child of the eyepoint. The difficulty comes when manually shifting the viewpoint and the cross-hair then strays from the reflector sight or windscreen glass!