gbadev.org forum archive

This is a read-only mirror of the content originally found on forum.gbadev.org (now offline), salvaged from Wayback machine copies. A new forum can be found here.

Coding > Juggling large amounts of sprite data

#10292 - poslundc - Mon Sep 01, 2003 9:21 pm

I was wondering if anyone could give me some insight into this problem...

A game like Secret of Mana for the SNES uses 32x32 sprites for its characters/enemies. Each character/enemy has about 24 different poses, and there are up to 6 characters/enemies on the screen at any given time.

Assuming 16-colour mode, this would require 72K of sprite tile data to implement, well over the 32K of character memory available for sprites. And that's not including things like visual effects and status displays!

I'm hoping to code something on a comparable scale (except with up to eight characters), and my first instinct was not to place all 24 poses in VRAM and only copy in those that I need. The problem is that the characters switch poses extremely frequently, and any of them could be called up at just about any time.

So here's the question: if I try to code a system where nearly every frame I copy 8 x 32 x 32 pixel's worth of data into character memory (basically 4K), am I trying to bite off more than the hardware will be able to chew? For that matter, am I doing something ludicrous?

If so, can someone perhaps advise me of a better way to handle this much sprite data?

Thanks,

Dan.

#10293 - tepples - Mon Sep 01, 2003 9:42 pm

poslundc wrote:
my first instinct was not to place all 24 poses in VRAM and only copy in those that I need.

Good instinct.

Quote:
So here's the question: if I try to code a system where nearly every frame I copy 8 x 32 x 32 pixel's worth of data into character memory (basically 4K), am I trying to bite off more than the hardware will be able to chew?

Heck no; it'll work fine. If you use uncompressed sprite data, you can DMA-copy sprite cel data from EWRAM to VRAM at 4 cycles per 2 bytes. With 68 scanlines in vblank, and 1232 cycles per scanline, this equals over 40 KB copied in one vblank.

Please read details in my white paper on GBA sprite cels.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.

#10294 - poslundc - Mon Sep 01, 2003 9:45 pm

Sweet, that's just what I was looking for. Thanks.

Dan.