[sci.virtual-worlds] world modelling

simon@cuisun.unige.ch (07/16/90)

A lot of what I've seen in this group seems to deal
with user interface devices for entering a
virtual reality. I was wondering if someone could
send me pointers to work on modelling and
the internal representation of virtual worlds.

In particular I'd be interested to know if there are any
modelling languages for describing/constructing virtual
worlds. For example, are there world models which include
processes in the virtual world as well as descriptions of
object locations and attributes? If so, has anyone devised
representations which make it easy to change global properties
of a virtual world (such as a world's physical laws)?

I'll post a summary of replies to the net...

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Simon J. Gibbs
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simon@cuisun.unige.ch (08/12/90)

Thanks to everyone who responded to my request about
modelling virtual realities. Here's a summary of the
initial replies I received. (Sorry for not posting earlier
but I've just returned from vacation).

Simon Gibbs	(simon@cui.unige.ch)
University of Geneva

============================================================================
> From: jgsmith@bcm.tmc.edu
Sorry for the vagueness of this response, but (don't you love messages that
start out with disclaimers)  I really think that an important part of the
interface to virtual worlds is going to grow out of object oriented hypermedia,
especially HyperCard.  In a recent post somewhere (I forgot where) I thought
I heard someone mention a software product that would tranlsate hypercard 
stacks to a similarly formatted program that works under windows (I think it
uses "books" instead of "cards").  The interesting thing was that this 
translation occured through some intermediary (standard?) language for 
describing object oriented environments.  If there really is such a standard
object oriented environment language, I think virtual world interfaces will
use it.  Sorry I don't have more info.  I'm gluing my eyes to the nets waiting
to hear more about it.  If you get any interesting news I would hope you pass
it on to the net.
============================================================================

> From: wex@pws.bull.com
>>   I was wondering if someone could send me pointers to work on modelling
>>   and the internal representation of virtual worlds.
As much as I hate to keep tooting my own horn, I have been working on this.
I will have a chapter in the forthcoming book, or you can see the abstracts.
Tim McFadden of Altos also had some interesting things to say based on an
Actors model.

--Alan Wexelblat
Bull Worldwide Information Systems	internet: wex@pws.bull.com
phone: (508) 294-7485 (new #)		Usenet: spdcc.com!know!wex
============================================================================

> From: Stan Shebs <shebs@apple.com>
I've designed and implemented a language for building virtual worlds to be
used for multi-player games.  Unfortunately, in the push to be more general,
and despite some effort, I ended up reinventing a strongly-typed Scheme with
a set of predefined object types (objects, spaces, etc).  I don't believe a
procedural language is entirely appropriate for this type of model building,
so am in the process of re-evaluation of the task, will maybe do a purely
declarative language (such as a constraint logic language).

						stan shebs
						shebs@apple.com

brucec%phoebus.phoebus.labs.tek.com@RELAY.CS.NET (08/17/90)

> 
>> From: Stan Shebs <shebs@apple.com>
> I've designed and implemented a language for building virtual worlds to be
> used for multi-player games.  Unfortunately, in the push to be more general,
> and despite some effort, I ended up reinventing a strongly-typed Scheme with
> a set of predefined object types (objects, spaces, etc).  I don't believe a
> procedural language is entirely appropriate for this type of model building,
> so am in the process of re-evaluation of the task, will maybe do a purely
> declarative language (such as a constraint logic language).
> 
>                         stan shebs
>                         shebs@apple.com
This looks like an interesting topic of discussion in itself: what
programming models suit world design best.  My own prejudice is that Stan
is right as far as saying that "a procedural language is [not] entirely
appropriate", but that a purely declarative language won't cut it either.
I tend towards a constraint description layer over an action layer in which
actions are described in some sort of polymorphic-procedural way, i.e., you
declaratively state how parts of the model are constrained, and then state
what actions will be taken to enforce the constraints, the actions to be in
fact dynamically bound so that knowledge of the actions' implementation is
not available to and not needed by the constraint declaration.  The object
of the polymorphism is to allow evolution of the model both as it is used
and in redesign.
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Bruce Cohen, Computer Research Lab        email: brucec@tekcrl.labs.tek.com
Tektronix Laboratories, Tektronix, Inc.                phone: (503)627-5241
M/S 50-662, P.O. Box 500, Beaverton, OR  97077
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NOTE: USE THIS ADDRESS TO REPLY, REPLY-TO IN HEADER MAY BE BROKEN!
Bruce Cohen, Computer Research Lab        email: brucec@tekcrl.labs.tek.com
Tektronix Laboratories, Tektronix, Inc.                phone: (503)627-5241
M/S 50-662, P.O. Box 500, Beaverton, OR  97077