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From: broehl@watserv1.waterloo.edu (Bernie Roehl)
Newsgroups: sci.virtual-worlds
Subject: Re: Who says what to whom (was Re: VR Protocols.)
Message-ID: <1990Sep21.192518.6956@watserv1.waterloo.edu>
Date: 21 Sep 90 19:25:18 GMT
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In article <7801@milton.u.washington.edu> wex@dali.pws.bull.com (Buckaroo Banzai
) writes:
>   If I list an attribute  *it* doesn't know about, that's
>   fine; it doesn't send it and I leave the attribute at its default value.
>
>So what's the default value for something like "has a door I can walk
>through"?  Do you see how much knowledge is presupposed simply in asking
>that question?

I don't think of a door as an attribute; I would say it's an object that's
contained within the room.

The door object sends its appearance, location, etc; if I (for example) touch
the doorknob, the door responds by altering its orientation and appearance
to show me whatever's on the other side.  I pass through the door, and I'm
(transparently) transported to another room.

In principle, I could bring a door to my house with me whereever I go, and
leave it behind in case people want to come over and visit.

>   [re gravity:] a Newtonian model is not necessarily what we want.  If I
>   were designing reality, I might well choose not to implement gravity
>   (even if doing so were easy, which it's not).  "Collisions" are often a
>   *bad* thing. 
>
>True, we might choose a relativistic model where gravity is a property of
>the space in which the objects interact.

Or even dispense with these complexities altogether (which was the original
intent of my statement).  A world in which I can simply float around,
perhaps by swimming through the ether, is immensely easier to model.

>The problem is that the people paying the bills were airlines; they wanted a
>system that more or less accurately modeled the real world.  Sure, it would
>be nice if we could drop annoying things like gravity and collisions...

... the very things most airlines would *love* to avoid :-)

>And I don't favor building up a protocol/system which is going to collapse the
>first time you throw a real problem at it.

Depending on what you mean by a "real problem"...

-- 
        Bernie Roehl, University of Waterloo Electrical Engineering Dept
        Mail: broehl@watserv1.waterloo.edu OR broehl@watserv1.UWaterloo.ca
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