[stella] Missiles and Ball

Subject: [stella] Missiles and Ball
From: Glenn Saunders <cybpunks@xxxxxxxxxxxxx>
Date: Mon, 24 May 1999 14:17:35 -0700
At 12:59 PM 5/25/99 -0700, you wrote:
>2. what exactly is the point of having missile and ball objects and how
>are they used
>    in already existing roms?

These are actually underutilized in most games, probably because designers
felt they couldn't get much mileage out of an object that is simply a 1-bit
strip.  In some games the ball, which is the same color as the playfield,
is used to fill in diagonal lines in the jaggy playfield.  For instance,
Radar Lock.  Because all sprites can have a width register and can be
precisely positioned horizontally per scanline, you can draw all sorts of
diagonal lines with them.  Missile Command is a good example there,
although I think it used players rather than missiles (hence the 30hz
flicker).

Bob Colbert was experimenting with the idea of using missiles as a kind of
limited version of a player, to help get more moving objects per scanline
without flicker.  You can create shapes that make it seem as thought the
missile has more than 1 bit of resolution by again using the width and
horizontal positioning per scanline.  You can not have more than 2 dots in
a missile per scanline, but you can acheive all sorts of shapes like
slashes, crosses, greater-than/less-thans, horizontal arrows, capital I's,
and so on.  I don't know of any games that really capitalized on this.

In some games the missiles were used as a starfield.  I believe Star Master
is one of them.  In others, the missile or ball was used to cover the HMOVE
lines, in mostly Activision games.


=========================================================
== Glenn Saunders  --3D Graphics / Videography / Web development--        ==
== krishna@xxxxxxxxxxxxxxx      http://www.geocities.com/Hollywood/1698 ==
== Stella@20 video page         http://users.cnmnetwork.com/~krishna
 ==
=========================================================


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