I don't see why this would require modifying the compass, though. At the most primitive level, this involves changing a "(facing >> 13) & 7" to "(facing >> 12) & 15" or even "(facing >> 11) & 31" to reduce the facing to the appropriate range, and then the existing facing-specific unit shp draw code would do its magic. On top of that there's FLH to adjust and that's probably all there is?
A lot of things are just graphical improvements.
I don't see why this would require modifying the compass, though. At the most primitive level, this involves changing a "(facing >> 13) & 7" to "(facing >> 12) & 15" or even "(facing >> 11) & 31" to reduce the facing to the appropriate range, and then the existing facing-specific unit shp draw code would do its magic. On top of that there's FLH to adjust and that's probably all there is?