Message-ID: <661@cwruecmp.UUCP>
Date: Sun, 18-Sep-83 18:29:36 EDT
Article-I.D.: cwruecmp.661
Posted: Sun Sep 18 18:29:36 1983
Date-Received: Mon, 19-Sep-83 00:51:27 EDT
Organization: CWRU Computer Engr. Cleveland, Ohio
Lines: 26

I've just returned to the net recently, so if this topic has
been covered already please don't flame too hard!

Someone suggested that the graphics in the StarWars game that's
out from Atari is really only slightly 3D.  "Slightly" means that
the ships in the first sequence, the red firing bases in the
second, and the catwalks in the third are the only things that
are really 3D.

All the other effects (stars, laser towers, etc) are really just
two-d line drawings which are moved by moving their endpoints through
what amounts to a vector field of accelerations.  Since at each moment
in time the perspective is fixed, they keep a grid of the acceleration
of each small area on the screen.  If a point of an object falls into
that area then it is accelerated using data values from the table.

The idea sounded good; last night I animated a flight down a 3D 
starfield on a TRS-80 Color Computer in BASIC, and with 10 stars
or so I still got a good 3D effect (without matrix multiplies!).
It sounds good and cheap - 3D animation for the cost of addition.

Has anyone seen this technique used on any other games?

	Andrew		Andrew Glassner    decvax/cwruecmp/glassner