Re: [stella] Remember this game?

Subject: Re: [stella] Remember this game?
From: Greg Troutman <mor@xxxxxxx>
Date: Thu, 31 Jul 1997 16:07:56 -0700
Piero Cavina wrote:
> 
> At 10:24 -0700 25-07-1997, Greg Troutman wrote:
> 
> >This isn't playable, but I thought I'd send you guys a demo to gawk at.
> 
> Sometimes they come back... very nice! :-) Who know why it wasn't done
> before...

You got me.  This one was my arcade favorite for months and I thought
surely it would end up on the VCS eventually...

> >I put this together over the past couple of days, and maybe I'll find a
> >month or two of free time to finish it!  Don't worry about the source.
> 
> Maybe?! We do need finished 2600 games!
> Like in any other Atari 2600 game, you'll need to plan carefully how the
> various elements can be put on the screen whitout too much troubles.
> 
> >Other than a first draft of a multi-sprite kernel there isn't really
> >much of interest.
> 
> At the moment I haven't the emulator here with me. Is it done in single or
> double scanline resolution?
> In the first case, GOOD LUCK. Otherwise...

That one was done in mostly double-scanline, but the newest is single
scanline throughout.  Also, the chunky mothership is now single-pixel
horizontal resolution.  Heh, a 29 pixels-wide, single-scanline object
with single color-clock horizontal motion.  Say that 10 times fast ;)

I wrote a coarse adjustment routine with single-cycle precision, then
use one of three copies of a 4 byte sprite (like you would use to draw a
logo or something) to provide motion in between coarse adjustments... 
Boy was that hard.  It still isn't working quite right, but it's obvious
it will.  The only drawback is the playfield has to be narrowed to
something like only 96 pixels wide (actually if I screw around and
detect if the ship is on the left or right side of the screen and write
separate positioning routines, I can prolly get back a lot of that)... 
But, in this game a narrower screen is kinda okay since it's so
seriously vertical.  I think the tradeoff is worthwhile to get near the
original resolution.

It's gonna be a while before I can post any updates though as a lot of
coding is needed, but I have very busy week ahead... 

> >Maybe after I get P0 to pass through a mess of P1's
> >without jittering ;)
> 
> ...why don't you take a look at my game source code? :-)

Okay. Where is it?

--
mor@xxxxxxx
http://www.crl.com/~mor/

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