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From: boulder!boulder!heuring@ncar.UCAR.EDU (Vincent Heuring)
Newsgroups: sci.virtual-worlds
Subject: Re: The collaborative nature of VR
Message-ID: <9461@milton.u.washington.edu>
Date: 17 Oct 90 19:48:09 GMT
References: <8374@milton.u.washington.edu> <8514@milton.u.washington.edu>
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In article <8514@milton.u.washington.edu> mike@x.co.uk (Mike Moore) writes:

>>Mike Moore (i.e. me) writes:
>>>  What I'm saying is that
>>> in a VR environment if we don't want people entering a room, we don't
>>> even tell them it's there, they just see a blank wall (or one with
>>> pictures hung on it, or whatever) and all the hacking in the world won't
>>> change that fact.  For people we do want to allow in there is simply an
>>> entry point, no messing around with doors just a 'transporter' machine/
>>> object which moves you into the chosen room/building/area/'country',
>>> wherever you intend going.
>>"transporter machine" is still a door in terms of its affordances.
>

Consistency is a virtue.  In VR, it may be a virtual virtue, but a virtue
nonetheless. It is inconsistent in VR and in the database to permit only
a certain class of user see the door.  It is sufficient to allow all
to percieve the door, but only a subclass open it.
Let the database be consistent, not changing for each
class of user.



>  To explain my point in
>this context, if I were denied access to a room by some security software,
>it would be in the best interests of the software to not even inform
>me of the existence of the room.

Hang the best interests of the software.  If the system security is
inadequate, *that* is what should be addressed.  This is analogous
to unix showing all directories at a given node, including their permissions.
drwx------ is a door closed to all except the owner of the room within.
Certainly this is to be preferred to a system where users can't even see
dir entries that they am not permitted to.  The system has to have consistency,
whether it is unix or VR.

>Buckaroo Banzai [wex@dali.pws.bull.com] writes:
>>But this begs the question.  If the objects in the room don't shout at you,
>>how do you know they're there?
>>How do you know what you can do with 
>>them?


You look around.  If you percieve an object, you poke it, or squeeze it,
or try to pick it up, twist it's knobs -- you get the point. If it
happens to be a door, you try the knob.  If it doesn't turn, you give up.
Maybe the door has a sign on it that says 


                 ECE 553 - Programming Language Theory
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---
 Vincent Heuring     Dep't of Electrical & Computer Engineering
 University of Colorado - Boulder  heuring@boulder.Colorado.EDU