Re: [stella] Collaboration

Subject: Re: [stella] Collaboration
From: Glenn Saunders <cybpunks2@xxxxxxxxxxxxx>
Date: Sun, 19 Jan 2003 10:44:56 -0800
Okay, comments on the latest build...

I noticed that the 2nd scanline of the grenade show up as gray from about 60% across the screen to the right end, and on the very left the first scanline is white.

The latter isn't a problem because I can make sure it doesn't wind up on the far left. But the former is more of an issue. I'd be happy if the 2nd scanline was _always_ white if you wanted to make it easy on yourself. That way we can brag that the game has multicolored sprites even if it's just the ball ;) I'd be content to have the grenade be only one scanline also although I realize that it would help differentiate it from the tombstone lines to make it two if I ever were to set it to 4-pixels wide. In BARRIER mode the color tearing might be inevitable I guess unless you blanked those lines.

The other issue is in relation to vertical wrapping. Skipdraw will not allow for the sprite to appear on screen more than once, so this will force a dead zone while wrapping, right? I can deal with this but I have to make sure the AI doesn't make the zombies hide in there. Right now the sprites are popping but on one of the previous builds they were wrapping. Can you make them wrap next?

Also, I noticed that by going to the interleaved missiles, the HMOVE lines are back to being every other line, so sprites COULD show through. Is the tearing fixed enough to allow the zombies to extend completely across the screen? If so we can go back to the safe zones being one-playfield-pixel in width which will look a bit more authentic. (I would still keep the cars from extending.)

Also we should be mindful of how much RAM is being used. I see 36 bytes used so far.

The kernel right now doesn't point to RAM for the tombstones, so remember that it's going to eat up 44 bytes. So we're already at 80 bytes of RAM. We're going to need ram for score, sound envelopes, animation, and more. So it's going to be tight.

The doubling of the Y position values is something I wish we didn't have to do and then we have a third copy for the missiles
M0_Y2 ds 1
M1_Y2 ds 1

I also don't see these being used.

krnlIdx     ds 1
vecKernel   ds 2

Is there any way we can do the tombstones via the Centipede %10101010 / %01010101 bit-masking trick (where each byte stores two rows of information since the mushrooms are spaced out and alternate) or is there not enough time on the 2nd grenade line to set that up? If we could do that we could gain 22 bytes of RAM.

---------------------------------------------------------------------------------------------- Archives (includes files) at Unsub & more at

Current Thread