Re: [stella] 'Look Ma No Flicker' revisited

Subject: Re: [stella] 'Look Ma No Flicker' revisited
From: "Glenn Saunders" <cybpunks@xxxxxxxxxxx>
Date: Wed, 29 Aug 2001 14:36:42 -0700

Thanks for the source, I'll have fun looking at it.

Have you found a game in the 2600 library with a kernel that would be good
for your purposes (four sprites/monochrome, no restrictions, no flicker,
single scanline res., symmetrical PF..)?

I don't need single-scanline res. Because of the pixel aspect difference (160x200 vs. 160x100) it creates, single scanline res is really only useful for sprite shapes that are more horizontally oriented and more static in orientation (like the ships in Atlantis). The rotating cars and the vertically oriented people don't really need the added vertical resolution unless I want to make them look squashed.

That's the same reason they have to be monochrome. Adding a gradient on the cars won't do much when they start rotating, and since the missiles inherit the color of their players, it would look weird on them.

The only game I can think of to study would be Super Challenge Football, but that doesn't have the playfield component.

All other games mentioned feature flicker of some kind (like Dig Dug) which is something I want to avoid.

I wish I had chosen a game that didn't need the playfield component since the main motivation, technically speaking, was to do interesting things with the missiles in order to give the illusion that the VCS has 4 8-bit-wide sprites rather than 2.

I think that considering that:

a) the players only have to be horizontally positioned once at the top of the screen, and
b) the missiles only have to be horiziontally positioned once at the top of the screen also, and only applying fine-control adjustments at the proper scanlines, and
c) having the sprites 2-scanlines tall instead of 1
d) only drawing the playfield every other scanline, and
e) having only PF1 and PF2 get rewritten, and

That it will free up enough time during the main kernel to perform all the logic and the register loads.

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