From: galt@dsd.es.com (Greg Alt - Perp)
Subject: Power Glove and low cost VR
Date: Tue, 28 May 91 22:18:28 GMT
Organization: Evans & Sutherland Computer Corp., Salt Lake City, UT



I just finished reading the 1990 archives, and I noticed that someone
said the guy that did the BYTE article was planning on reverse 
engineering the hi-res mode from the game GloveBall.  Is this true?  
if so, when?  Also, are there any reasons why I would want to pay $400+
to get a Private Eye when I can get a sony watchman for only $100?
What sort of difficulties are there with the optics?  Once we get power
gloves working in hi-res mode and once we find a suitable low-cost 
alternative to eyephones, we can finally get down to programming...

I have all the necessary matrix routines (for rotation/translation/etc.
as well as perspective view).  I also think that building a wire-frame
system would be a piece of cake (once you have the matrices, transform
the endpoints and draw the lines).  I'm mostly a software type, so I 
am getting very anxious for the hardware to come.  If people would like
the matrix routines, I could post them, but it might be better to wait 
until people have the hardware.

This weekend, I was brainstorming, and I had a few ideas that might 
simplify things.  First, I only want sit-down VR.  I am perfectly happy
with being restricted to my chair, with only head rotations (and not
position) being used.  It could be thought of as sitting in an invisible
vehicle that you can not move around inside, but (with gesture commands)
you can move the vehicle.  Now, what is the best way to get head 
rotations into the computer?  It is hard to believe that such a system
would cost more than $100 to build.  Could it be done with a bunch of
mercury switches?  (but then, there is the problem of Y axis rotation).
Maybe Y axis rotation could be obtained by rotating the chair?
Is Z axis rotation (tilting your head sideways) really that important?
If you use only rotation, you could possibly use the 4 analog inputs 
available on the game port.
Also, what sort of resolution would be necessary?  The range is is about
120 degrees for X rotation, 170 for Y, and 90 for Z.  I would think 
5 degress would be sufficient (which means you would only need 5 bits of
info per axis).  Does anyone know how many bits you can get from a 
game port?   
 
     Greg