From: dlwood@mailbox.syr.edu (David L Wood)
Subject: Re: DESIGN: Doors between virtual worlds
Date: Fri, 14 Aug 92 00:09:11 EDT



In article <BstptD.Ezq@watserv1.uwaterloo.ca>
dstamp@watserv1.uwaterloo.ca (Dave Stampe-Psy+Eng) writes:

>The easiest way to do this is still to make a visual link to the area
>you're viewing through the portal.  Then your machine is doing the
>work, not someone else's.  The link functions as if an extension was
>made to your region-- visible elements of your region become invisible
>behind the portal, and objects from the viewed region are put in place
>using the desired portal region transform.  THis handles "weird space"
>portals nicely as well.  When the portal dies, the objects are removed
>from your viewspace.

If the door were defined as an object that receives (requests) message
packets from objects within a certain volume (those on the one side of
the door facing AWAY from you, follow?) and perhaps even having the
door object run some code on a networked machine to do a bit of
clipping around the edges, then send the results back to you, the
user, then the work would be halfway done, and you would have
non-static pictures on the door.  One reason for using an object
running linked code would be to reduce bandwidth, since having an eye
on two locations in the virtual environment is akin to having two user
objects and all the mess that that entails (too much trying to be sent
to the user).  With the door object running code on a net.machine, it
could also update itself as you see fit.  The door could also have
within it's linked code a formula to determine size/distance for the
actual projection onto the door, in an effort to eliminate objects
that are not visible.  Hmm, doors are smarter than I thought! :-)

>Any opinions on the render-and-copy versus the visibility link?

I think the visibility link coupled with an intelligent door would be
the most efficient for low end systems.  For the SGI connected via
ethernet to the router, however, a render-and-copy method would
produce >slightly< better images, IMO.  --

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| dlwood@mailbox.syr.edu | Gigs and gigs of NiCad memory, bummer.. | |
Cybernaut, with a thought.  | Why buy the leading brand; 90% hate it.
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