RE: [stella] Ms. Pac Man, Mr. Do, striped playfields, and one-line kernels

Subject: RE: [stella] Ms. Pac Man, Mr. Do, striped playfields, and one-line kernels
From: Thomas Boutell <boutell@xxxxxxxxxxx>
Date: Wed, 1 Sep 2004 08:54:26 -0700 (PDT)
On Wed, 1 Sep 2004, Ben Larson wrote:

> > I was able to get around using skipdraw by
> > page-aligning my sprites and
> > padding the top (remember, it's stored upside down)
> > with zeroes to fill up
> > the page.  
> That's what I also did in 'Incoming'.  Wastes a lot of
> ROM, but can't be beat speed-wise.
> All said and done, by doing that and unrolling the
> kernel such that each iteration draws 8 lines, I was
> able to do a full-width asymmetrical playfield, an
> X-position-independent player and ball, an
> X-position-dependent player (right side of the screen
> only), and also change background and playfield colors
> every 8 lines.  Pretty tight code though...

I just did a bit of arithmetic and found that I'd need
1,792 bytes just for my padded page-aligned sprites... and
I need a lot of ROM already to unroll my kernel as much as 
I have. And the game doesn't look bad at all with 
the double-height, non-padded versions of the sprites, which 
saves so much ROM that I could probably have multiple
versions and animate them. That might turn out to be a lot 
niftier to look at than full resolution would be. 

I'm definitely going to need the striping trick, 
though, in order to do flicker minimization.

Now that I've figured out DASM macros, unrolled
kernels aren't nearly as scary or as tedious to work on.

Thanks for all the commentary, folks. This is very
thought-provoking stuff. 

Thomas Boutell
Boutell.Com, Inc.                              

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