Re: [stella] The Big Sprite

Subject: Re: [stella] The Big Sprite
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
Date: Wed, 8 Apr 1998 14:04:44 -0400 (EDT)
> I don't think this kind of thing has ever been done before.  Quite
> impressive.  At first I thought this MK stuff was just a joke, and
> certainly the game would normally be considered impossible in any form on
> the 2600, but now I can see that it might actually be possible.  It's just

I know I originally posted the "MK might be possible" message on April
1st :), but it wasn't intended as a joke.  I'm not planning to actually do
the whole thing, but if someone, maybe Eckhard, wants to do it, I'll lend
help and ideas.

> a shame that the BG on the scanlines with the big sprites has to be
> completely black.  MK was known for its detailed backgrounds.  As for the
> flicker, 30hz flicker is fine.  It's 15 and 7hz flicker that starts to
> really look bad.

The background could be completely blue or completely green instead of
black if you'd like :)  Maybe a few cycles for a gradient culd be found,
but no playfield data.

> If you could free up the ball or the missiles you might be able to at
> least sprinkle some pixels in there implying blood sprays ;)

Oh, they're completely free.. it's just   that there aren't enough cycles
to process them :)  As I posted before, using the ball for a projectile
weapon might be doable, and *maaaaybe* for blood sprays, though the only
way I can think of to do it is flicker a few blood particles at 15 or 10
hz, and have the characters unable to throw projectiles while their
oppoenent is spewing blood.  (and both the projectiles and blood are limited to 8
pixels wide because the ball is, unfortunately - no Scorpion harpoons)

Doing anything with the missiles would be difficult (well, more so than
the whole thing already is :) ), since they'd have to share the color of
the players, and there'd be three copies of them because they share the
players' NUSIZ.  

> Another approach to this game would be to use Suicide Mission stipple
> bitmap graphics.  You won't get as solid an image, but you'd be able to do
> a limited background at the same time.  Of course, if this mode is limited
> to the SC, there may not be enough memory to hold the gfx necessary vs. a
> hugely banked ROM...

I thought of that too... the problem with that is the sheer number of
cycles needed to calculate the graphics.  IIRC, it takes something like 12
cycles per byte to read it and store it in the "display-buffer" in SC
RAM, and probably another five or so to handle looping... at 17 cycles for
each of the 256 bytes making up a character frame, that'd be 4352 cycles
per character.  Recall that there's 67*76 = 5092 cycles total in overscan
plus vblank.  And that doesn't count processing the other character, or
erasing this character's previous frame.  Also, rememeber that tthe
stipple graphics only cover 3/5 of the screen width.

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