Re: [stella] Star Fire - Return of the Starfield ?!?

Subject: Re: [stella] Star Fire - Return of the Starfield ?!?
From: "Clay Halliwell" <clay.h@xxxxxxxxxxxxxxxx>
Date: Fri, 26 Jul 2002 14:38:08 -0500
----- Original Message -----
From: "Manuel Polik" <cybergoth@xxxxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Wednesday, July 24, 2002 3:04 PM
Subject: Re: [stella] Star Fire - Return of the Starfield ?!? (was: Strange
Z26 (real thing?) behaviour discovered...)

> That won't work. +8 does the trick, nothing else.

I think someone mentioned this already, but (if I'm understanding the
problem correctly) this can be fixed by manually positioning the first star
at the top of each frame. This is good programming practice anyway... you
don't want to depend on preexisting register values if you can help it.

> Total randomness won't work, since you've got to *repeat*
> what you're doing every frame

I think a small table of ~20 entries would work for this. Each would contain
a valid HMOVE value, which would be repeated (/me grabs calculator)... uhm,
23 times to allow arbitrary positioning of each star. So if you left the
missile turned on, you'd see a zigzag pattern going down the screen.

To increase the rather sparse star density this technique would yield, you
could flicker with a second 50%-offset starfield, or use another missile. I
guess it depends on where you have cycles to spare.


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