Re: [stella] Asymmetrical Reflected Playfield

Subject: Re: [stella] Asymmetrical Reflected Playfield
From: "Glenn Saunders" <cybpunks@xxxxxxxxxxx>
Date: Fri, 21 Sep 2001 15:41:55 -0700

BTW: I didn't receive the reply of Glenn. Was it posted
directly to you Erik?

I'm not really going to explore this particular kernel anymore because by itself it isn't what I need for Death Derby. For the sake of a generic demo, it runs okay so I'll leave it at that and move to the next iteration.

For Death Derby I envision that PF0 gets written once at the start of the playfield after the score, and then never has to be rewritten again across the entire psuedobitmap screen. So I'd only have to do 4 writes to the playfield registers. I could then have a 2-line kernel where on odd lines I draw the tombstones and on even lines I quickly blank out the middle of the playfield and load up the sprites. And hopefully in the spaces between there will be enough time for the necessary logic involved in all this. The compromise would therefore be for the tombstones to be striped, but the PF0 border would still remain solid.

I'd then only need 4 20-byte-long strips of RAM for each playfield write and no last-minute bit shifting or masking would be necessary to get them onto the screen.

The next version I attempt will probably be a static (ROM-based) playfield bitmap where each block is 8-lines height, with the fixed PF0 borders and the alternating (striped) interior. Then I'll move it to RAM and then try to get the cars to load.

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