In working on my cockpit, I am attempting to make a custom HUD with switchable modes and am looking at the available data via the UDP CommServer.
Data Included already:
Additional data needed:
-X axis movement speed (left/right) for hover bug
-Z axis movement speed (forward/backward) for hover bug
-Waypoint ETA String
-Target relative altitude (to triangulate cursor position)
-Target relative distance (to triangulate cursor position)
-Current selected Weapon
-Current selected ammo count
-TADS X position
-TADS Y position
Slip and Indicated airspeed may provide the x/z axis data, but with wind, would be inaccurate for hover operations.
If this new HUD is going to be able to vary it's output based on the user's head (via headtracking interface), the program will need the data from the pilot's perspective, then mathmatically compute the difference between where dead center view shows the symbols versus the X/Y/Z rotation of the pilot's head.
I have no doubt that with a TrackIR-like headtracking interface into the HUD program and today's tech a budget-wise HMD can be created similar to the monocle (with only exception being the NVG/FLIR output).