Re: [stella] Sprite Delema

Subject: Re: [stella] Sprite Delema
From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx>
Date: Thu, 19 Mar 1998 09:29:22 -0500 (EST)
> I was wandering if there could be way to position two sprites with a
> variable spacing in the same scanline.
> Ie: you have a "left" and a "right" sprite. Do a delay loop, reset the left
> sprite, do another delay loop proportional to (right sprite position-left
> sprite position), and reset the other sprite. Hmmm, probably this isn't
> always possible, but..

What if the two sprites overlap?  Suppose the sprites are both at pixel 88
from WSYNC.  You'd have to do the first RESP0 at cycle 25 (ends at cycle
27; *3 = 81; +5 = 86) and then HMOVE it two pixels.  The earliest possible
time to end the RESP1 is cycle 30; *3 = 90; +5 = pixel 95, and then HMOVE
it left seven pixels.  It's theoretically doable, but looks like it'd take
some pretty darn complicated code, definitely involving
single-cycle-precision delays.  And the overhead might take an entire
scanline to set up anyway, killing the point of what we were doing. :)

If you can ensure the sprites won't overlap - maybe an Air-Sea Battle type
of thing where each player is confined to his own half, or a Street
Racer-style game - it might be doable with regular DEY/BNE logic.


--
Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/stella.html
Don't post pirate BINs to Stellalist.  Be a programmer, not a pirate.
Write the best game, win framed autographs of famous Atari alumni!!

Current Thread