SpritesMind.Net

Hi guys!

I am reading some info about sending the sprite table without DMA because DMA can cause some glitches for this operation. Is that right? Do you know the reason for that?

Thanks!

You can get problems when you update sprite table during active frame regardless of using CPU or DMA to do the transfer.

I've recently gone down the DMA route and it's working just fine for me.

Previously I was setting individual sprite properties (X, Y, flip flags) by reading bytes from the VDP, setting values and writing them back, but this slowed my game down to a crawl.

Now I keep a local copy of the entire sprite table in RAM, and DMA it across in the vertical interrupt routine. Works a treat!

BigEvilCorporation wrote:Now I keep a local copy of the entire sprite table in RAM, and DMA it across in the vertical interrupt routine. Works a treat!

I usually do that, but in some wikis say that DMA works fine but the cache should not be completely update, causing some problems with the drawn sprites. I have some random sprite disappearing (not because a known reason) and the problem should be DMA writing. I see that SGDK did not use DMA also for that stuff, so i think it should be a good reason.

The cache not updating happens when your DMA (or CPU transfer) reaches active frame. When your update happens and finishes in the blanking/border there will not be problems.

Next SGDK version will use DMA for sprites update. Definitely use it if you can, it's a lot faster than updating sprites independently and from 68K.

Ok i understand. Thanks guys!!!