Re: [stella] Trick12 - inv3.bin

Subject: Re: [stella] Trick12 - inv3.bin
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
Date: Tue, 13 Mar 2001 21:41:15 -0500
On Mon, 12 Mar 2001 19:58:57 -0500, you wrote:

>At 12:45 PM 3/12/01 -0500, Erik Mooney wrote:
>>The tricky part is not drawing the 11 x 5 grid, it's being
>>able to turn on and off each individual invader.  
>Well, Thomas' demo used two different colors for the 12 players seemingly
>at random (moving player copies around or changing the color on the fly?  I
>haven't looked at the source,) so why not just make one of the colors
>black.... assuming he used the latter method.

That may work for the invaders routine.  Although, the invaders one
actually draws 15 players - think of it as 15 cells across the playfield,
of which 11 consecutive are occupied.  If the 12-player multi-color one
can be modified to start at different positions, it could certainly be
used that way.

>>There is definitely no
>>time on scanlines occupied by invaders to draw missiles, BUT there _is_
>>time on the scanlines between rows of invaders -- a missile can be turned
>>on at that time and then turned off during the next gap.
>Yeah, that's what I was thinking.  (The other way would be to do a flicker
>thing, but I suppose a whole flickering row or even half of one would look
>pretty nasty.)
>Very sexy btw.  I get a couple little missile-sized artifacts using
>xstella, but that's xstella.

Actually.. those aren't artifacts, those are missiles :)  I never
positioned them, so they're in whatever position they land in when the
code zeroes out the machine.  I didn't even realize this when I posted it
(its been that long), but there _is_ time to do one indexed-indirect
lookup and store to ENAM0.  It's in the code, though I hadn't quite
figured out how to use that to do the missiles.

(In the binary I posted, make sure you press Reset to start the action;
the invaders move.  I hadn't said that before.)

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