Re: [stella] Re: 2600Cookbook - exact horizontal positioning

Subject: Re: [stella] Re: 2600Cookbook - exact horizontal positioning
From: KirkIsrael@xxxxxxxxxxxxx
Date: 14 Apr 2004 04:31:33 -0000
> On Tue, 13 Apr 2004 19:15:20 -0400, you wrote:
> >> This post gives a detailed explanation of exact horizontal positioning:
> >>
> >>

> >A better method is the one rediscovered by Manuel in Battlezone and the
> >variations of it:
> >
> Well, it's a classic trade-off.  :)  The Battlezone routine is certainly
> better than the old Air-Sea Battle conversion routine, but the
> lookup-table approach is still faster (at the cost of ROM, of course); it
> fits entirely into one scanline plus an HMOVE afterwards.
> Kirk, do you have an opinion as to which of the three would be best for
> 2600 101?  Battlezone is compact, but getting the fine/coarse coordinate
> is intertwined with the delay loop and hard to explain.  Air-Sea Battle
> goes through an incomprehensible block of code but at least gets a visible
> understandable byte with the fine/coarse numbers.  The table lookup also
> gets that, but it might be hard to grasp exactly what the table itself
> means.

I hadn't heard much about the Air-Sea Battle one.
Is there a nickname for the one Andrew Davie teaches? Or is that the
Air-Sea Battle one, and there's a third technique I've heard nothing

Well, that brings up one obvious task: give these techniques nicknames,
and I think "Battlezone" "Air-Sea Battle" and...wherever the third one 
was first noticed (or utilized, if a homebrew).

Andrew teaches his pretty well, so I'd probably focus on Battlezone,
whose savings in time seems like a good benefit, and make a very big 
clear reference to Andrew Davie's lesson.  I guess I'm willing to say "just
use this, it works even if you don't fully understand the mathamagic

   "God made everything out of nothing, but the nothingness shows through." 
         --Paul Valery 

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