[atari7800] Re: DLIs?

  • From: "Eric Ball" <ek-ball@xxxxxxxxxx>
  • To: <atari7800@xxxxxxxxxxxxx>
  • Date: Wed, 28 Jan 2004 22:32:13 -0500

> I was thinking of something like a split screen racer with player 1 on the
> left and player 2 on the right. Another idea would be to have the game on
> the left side of the screen and the score/status on the right sort of like
> Eduardo Mello's Space Invaders Collection for the Colecovision.

You should be able to accomplish what you want by just using standard
display lists.  The HPOS values for the left side would be 0-79 and 80-159
for the right side.  You will need to create a gutter in the center using a
sprite the same as the background (not using the background color because
that would be transparent :-) ) if your sprites can go "offscreen" side to
side.  (This "gutter" sprite should be the last sprite in each display list
so it is drawn on top.)

You may want to avoid using tiles (aka indirect or character) sprites if you
are scrolling vertically, because then it would be impossible to scroll each
half independently.  (I _will_ get my tile scrolling demo done . . . one of
these days.)  This is because the bottom of an indirect sprite is on the
last line of the zone, which goes across the whole screen.

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