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

Subject: Re: [stella] 'Look Ma No Flicker' revisited
From: Erik Mooney <erik@xxxxxxxxxx>
Date: Wed, 29 Aug 2001 18:27:25 -0400
8/29/2001 5:36:42 PM, "Glenn Saunders" <cybpunks@xxxxxxxxxxx> wrote:

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

It has repositioning of both (!) missiles multiple times during the kernel, and also
does add the ball to the mix.  It would certainly be an interesting study, I

>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 

Hahahah.  I've been there, with INV, the other way round.  It started out as a
tech demo of what can be done with the playfield registers and the code just
kinda got out of control squeezing in player objects.

>the missiles in order to give the illusion that the VCS has 4 8-bit-wide 
>sprites rather than 2.

SC Football already definitively does it, so you aren't really doing
anything strictly new technically.  More so the challenge here is to create
believable sprite shapes within the constraints of the missile objects.  (You
might even just copy SC Football's missile-sprites for the running men.)

>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

Well, you'll have to apply a fine-control adjustment (even if it's just an empty
HMOVE after an HMCLR) on every scanline unless you want an ugly
"comb" effect like Missile Command.

>c) having the sprites 2-scanlines tall instead of 1
>d) only drawing the playfield every other scanline, and

Just off the cuff, this I think would be fairly ugly.  I could never stand the
striped paddles in Video Olympics or striped scores in several games.  With
optimization to hang on to playfield bytes after fetching them (TXS / TSX
being the obvious), I think you can do it.

>e) having only PF1 and PF2 get rewritten, and

And of course if you're using reflected-playfield, the PF2 rewrite must be timed

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