Re: [stella] Collaboration

Subject: Re: [stella] Collaboration
From: Thomas Jentzsch <tjentzsch@xxxxxx>
Date: Sat, 18 Jan 2003 09:00:29 +0100
Glenn wrote:
> For the time being let's just have one ball on screen at once.  That ball
> will either go across the entire screen (barrier mode) or just one of the 
> designated grenade lines.


> When in grenade mode, we'll be able to load a custom color.  The width and 
> position would be determined outside the kernel.)


> How that will probably work is the safe-zone will always colorize on
> all grenade lines and normally that would be set to the same color as
> the previous scanlines...


> ...but would all switch when another color is written to that RAM
> locatiion--because they would all be using the same repeated general
> purpose kernel.

That means, that you don't care if in a grenade line the safe zone
changes it's color too. Right?

> Given those limitations can't we do all the calculations with no more 
> kernels than you are planning?

Yes, that should work.

> I don't mind the gradients on the barrier or the safe zones enough to lose
> cycles trying to get rid of them.

That's not the big problem, because those writes only take three cycles.

> I thought you already solved that.  Ouch.

Nearly. :-)

> Like I said, you can cheat the screen width inward by one additional
> playfield pixel on each end as a last resort.  But it looks like we're 
> going to need more kernels with different write timings keyed to the X 
> positions of the objects.  I was expecting that.

No, that also wouldn't work due to the grouping that I described in my
reply to Chris.

> I was already prepared to give up the single pixel Y-positioning of the
> zombies a long time ago.  If it saves you the time, please consider that a 
> final decision in order to avoid the tearing problems.

I'm still quite convinced that the tearing problem is avoidable. But the
solution might eat some precious cycles (plus a lot of extra ROM) that
you might rather use for other things (coloring, balls, wider PF/safe

> This will just make the zombies move a little jerky on the Y axis but I 
> think the walk cycle animation will help mask it.

You could write a very simple single-zombie kernel, implement some
animations and AI movement patterns and then find out how it looks.

This is IMO important, because then it's easier to decide which
compromises we should make.

Have fun!
Thomas Jentzsch         | *** Every bit is sacred ! ***
tjentzsch at web dot de |

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