Re: [stella] Eighteen Sprites?

Subject: Re: [stella] Eighteen Sprites?
From: Eckhard Stolberg <Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx>
Date: Sat, 29 Aug 1998 15:20:21 +0200
At 11:24 28.08.98 -0700, you wrote:
>Hmmm...  What if spacing isn't that important?  This variation of
>multi-sprite trick has extra time in the display loop.  Do you think this
>extra time could be used for a text display or score routine with more than
>six digits?  Maybe the odd spacing could be compensated for in the font.
>Different graphics for different positions...  Just wondering.

I don't think so. There are only a couple of cycles left every
fourth sprite. You can't change the graphics fast enough for
a wider text display.

But I compared trick18.asm with the extra life routine in Robrot Tank
to see how to improve the spacing. Both routines are very similar.
If you do 5 free cycles instead of 6 and shift the graphics for
GRP1 one pixel to the left, you can get a much better display.
Also you need to put in one cycle before the first RESP0, since
your demo hits it too early.

That way only the gap after every fourth sprite is one pixel too wide
and one full sprite spills over to the left side of screen, but if
it is good enough for Activision, I shouldn't complain. :-)

Robot Tank uses the playfield to blank out the unwanted extra tanks.
The 18 spite version doesn't have the cycles left to change all 6
PF registers in time, but I think if you use several different
routines, that change only the nessessary registers, it might be
possible to do an 18 sprites extra life display.

Ciao, Eckhard Stolberg

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