I would imagine for things like the tie fighters,
the 3D coordinate information is stored somehow,
and then there is an actual 3D to 2D projection
done in the software to draw them on the screen -
Probably by the mathbox. Hence, they look different
every frame.
At one point I disassembled most of the sound rom
in that game but never delved far into the game
roms. I'd be interested in whatever you find out,
though ;)
-Frank
