[stella] Question about REFPx in early games

Subject: [stella] Question about REFPx in early games
From: Glenn Saunders <mos6507@xxxxxxxxxxx>
Date: Wed, 07 Jan 2004 19:18:27 -0800
I noticed so far in the Combat and Indy 500 disassembly that the way rotated sprites are normally handled in the early games is to store the top half of rotations and then copy the appropriate shape to a strip of RAM inbetween frames.

I can understand copying to RAM to save time in the kernel (although it eats up 16 precious bytes) but what I don't understand is why they don't take proper advantage of REFP0 and REFP1.

Combat could have saved 96 bytes of ROM (minus the extra logic to determine REFPx) by doing this, just storing 5 degrees' worth of sprite shapes per vehicle.

REFPx is still used in Combat, but it could have been eliminated with more logic to determine which frame to display since all of the necessary angles for both the left and right sides are already in the ROM.

I'm just surprised that in a 2K game not all possible optimizations were explored.

Any ideas from those who have looked at the source?

Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/

Current Thread