From: John Eagan <76130.2225@CompuServe.COM>
Subject: Re: DESIGN: Doors between virtual worlds
Originator: hlab@milton.u.washington.edu
Organization: University of Washington
Date: Wed, 12 Aug 1992 22:39:39 GMT



autodesk!robertj@uunet.UU.NET (Young Rob Jellinghaus) writes:  

>Ah.  This assumes that the "visual representation" of this portal-door
>can in fact be a projected perspective onto another place.  (It can't
>be a static projection, as then it'd just be a painting.  It needs to
>change in perspective as you move around looking into it.)
>
>I was just thinking of what this kind of door would look like, and it
>occurred to me that there is a physical counterpart: a hologram!    
>(stuff deleted)
>These "dimensional doors" would be essentially
>cyberspatial holograms, which allow you to teleport to the space on
>the "other side" by walking through them.  (And what's more, they
>could be _moving_ holograms!)
>
>Your description above seems slightly inaccurate in one regard,
>though: the passage won't just add an offset to your coordinates, as
>the world you are passing into may have an _entirely different_
>coordinate system.  This kind of door might be more than just a way to
>get from one part of your universe to another--it might be a gateway
>to another universe altogether, in which case something weirder than
>coordinate translation is going on.
>
>Now the question is:  how hard is it actually to implement a cyber-
>spatial renderer capable of depicting virtual holograms?  I doubt it's
>entirely trivial, as most renderers currently assume that all the
>objects they're rendering are present in "real" virtual space, not
>"virtual", holographic virtual space.  (Virtual virtual space!)

I'm not sure that I understand the Holograph idea...(maybe something
like, the Portal contains some sort of mapping of the whole Universe?
Me puzzled.<grunt>)...but Rob put his finger on a key point about
this, at least in the concept I've started to form based on Rob's
earlier idea of portals. That is, entering a Portal doesn't induce any
sort of coordinate offset.

The way I'm thinking of this (see earlier posts), is that each World
is a completely separate, discrete unit. Each World contains it's own
specific coordinates. (for one thing, part of the idea is that you
want to be able to have whatever scale of dimensions you want in a
particular World of your design...one person might want to create
"Amoeba World", where a millimeter is a hefty distance, another World
might be an astronomical model where a million miles is a trivial
distance...the entire Universe will be simplified considerably if each
World has it's own rules and characteristics, with no relation to
those of any other World, except that there would be some common
method of defining them)

The way I'm starting to look at this is first, the Universe would be a
simple matrix of objects acting as Portals. If it is a matrix, as in a
cubic sort of arrangement, you could navigate "virtually" through the
matrix to get to the Portal for the World you want, or there could
also be an addressing system based on 3d coordinates....i.e., you
could go directly to a "known" World by typing, say, "1.235.24" and
one would then be located at the Portal for that World.

For the Portals themselves, my thought was that a Portal would be like
any other object in the sense that objects would be defined as a
certain visual appearance, and have associated with it an action or
actions that can be triggered by collision detection using the user's
coordinates from a glove or whatever.

A Portal, as seen from inside a World, would be an object sitting in
that World, like any other, with it's own appearance and a location
defined in that World's coordinate system. The action triggered in the
case of the Portal "object" would be to immediately take you "outside"
(if you're in the World and want to go back to the Universe level)
leaving you beside the Portal representation in the Universe matrix,
or if you're in the Universe matrix and want to enter a World, would
cause you to enter a World, dropping you at the location coordinates
of the enter/exit Portal as represented inside the World.
 
I might be being overly simplistic about this, but to me it seems like
this whole thing could be made much more complex than it needs to be,
in metaphors like holographs and n-dimension folded space and all
kinds of things that provide big fun for pure mathematicians. It may
be stating the painfully obvious, but maybe it's worth mentioning to
remember that this isn't the Real World we're talking about. If, in
our virtual Universe, we want to instantly move from one World to
another, we're not forced to deal with trying to devise some "wormhole
in space" or some knotty cosmological theories, we're just talking
about discrete blocks of data to be loaded in and out. It seems to be
just that simple, if the organization suggested earlier is used.
Triggering a Portal object just causes a new set of data to be loaded
in, and the machine then deals with whatever the setup is for that,
starting by placing you at that World's coordinates for where the
Portal object is in that World, or if you're returning from a World
back "out" to the Universe, you get the Universe setup and your
location is that spot in the Universe cordinate system. No great
convolutions, no virtual cosmology, just collision detection, causing
that to load in the data for the domain you're entering and drop your
virtual self at the door.

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*John Eagan                         "humans is funny critters.." *
*VR section leader                                   -me         *
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