Re: [stella] missile bit width

Subject: Re: [stella] missile bit width
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Mon, 08 Sep 1997 01:52:26 GMT
>Yes, this gives you the illusion of having a 8-bits to play with, just
>like players, but you can't do shapes like: 
>XX  XX  
>Or odd widths like:

So, instead of lamenting the lack of those shapes, you design objects
that don't need those shapes.  Simple. :)

>Yes, this could translate into other games as a way to create more
>detailed objects.  The missiles and ball have often been underutilized by
>programmers, IMHO.
>What if you combined this technique with copies?  3 copies of players,
>missiles, and ball would = 12 total copies.
>Can the missiles and ball be copied as well?

The missiles share the same NUSIZ copy-combination as the players
(look at the two- and three-plane games in Combat).  The ball can't be
copied, though it can be extended to 1, 2, 4, or 8 pixels wide.

>Maybe doing this, and changing the shapes on the fly, it might be possible
>to do a flicker-free 12-character credit scroll after all.
>Some characters could be done with the missiles: 1, l, i, t, j, -, (, ),
>",", "'", +, =, /, \, |.  If you fudge it with "filled" characters you can
>do most of them with the missiles.

Possibly at double-resolution, though not at single.  It takes me 70
cycles to load/store two graphics registers, two NUSIZ registers (for
missile width), two HMM registers, and two color registers, and do the
HMOVE.  Problem is that the missiles will be copied if the player
graphics are copied... you can't do, say, two copies of each player
and one copy of each missile.  Maybe you could get eight, possibly
nine with the ball, but I doubt 12.

>They didn't have to be missiles since there are only two maximum per

The warlords?  Notice that the player-object shields can also move
onto those scanlines.  And it'd be much easier to draw the warlords
with missiles than rewriting GRPx between displayed copies.  Also, a
quick check in PC Atari's debugger shows the M0 and M1 positions to be
at 12 and 138, correct for the warlord positioning.

>I still think that Warlords is a game that needs to be rewritten.  If I
>ever do figure out how to program the 2600, I will cut my teeth on
>rewriting Warlords as an exercise.

Why?  Isn't it great as-is?

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