Re: [stella] Gunfight 2600: Design thoughts

Subject: Re: [stella] Gunfight 2600: Design thoughts
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
Date: Thu, 19 Apr 2001 05:58:21 -0400
On Thu, 19 Apr 2001 00:06:55 +0200, you wrote:

>First thing is that you'd have to rewrite PF2 two times on both lines of
>the 2LK, which I just don't have the cycles to. 
>Second is that you'd have to time the second write to PF2 so exactly,
>that it's value changes at the very pixel both PF2s touch. (Has anyone
>ever tried that?)

It has been done, yes... it isn't that difficult if you can time the
kernel to have the write in the correct place.  IIRC, you have a
four-color-clock margin; you can change PF2 while it is scanning out the
last playfield-pixel (4 clocks wide).

You could be sneaky and never have an obstacle occupying the last pixel of
PF2 and the first pixel of Reflected-PF2, and that gives you some
flexibility in timing the write.

>The only other way I can think of ATM is to skip shootable obstacles
>completely, but offer lots of different obstacle layouts instead, like
>the river, some rocky/fency areas, a train, a coach, a tree and a cactus
>for example...

I think this would be okay.  Let some of the obstacles move around during
gameplay, and that will provide a reasonable dynamic environment like you
were striving for with shootable obstacles.

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