Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!dali.cs.montana.edu!milton!mike@x.co.uk From: mike@x.co.uk (Mike Moore) Newsgroups: sci.virtual-worlds Subject: Re: Who says what to whom (was Re: VR Protocols.) Message-ID: <8204@milton.u.washington.edu> Date: 26 Sep 90 13:55:30 GMT References: <31304@unix.cis.pitt.edu> <7507@milton.u.washington.edu> <7801@milto Sender: hlab@milton.u.washington.edu Organization: IXI Limited, Cambridge, UK Lines: 72 Approved: hitl@hardy.u.washington.edu broehl@watserv1.waterloo.edu (Bernie Roehl) writes: > > >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. As an interjection: It strikes me that this is an example of the kind of behaviour necessary in the real world, but not in virtual reality. 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. With regards to the object attribute protocol: In my (humble) opinion, there isn't a need for every object to shout it's attributes at me when I enter a room. An object is a passive item that is acted on, and, if I perform an action recognised by the object it performs an action of it's own. i.e. I swing the baseball bat, the baseball bat pushes the baseball, the baseball alters its trajectory *and* pushes the baseball bat, the baseball bat pushes me. The space in which each of the objects (including me) exists defines the trajectory rules that the ball operates on, and baseball bat operates on me (i.e. friction due to my feet touching the ground - ground, what ground? I'm spinning!) The baseball bat, the baseball, myself and the space in which we exist can be processing on entirely seperate machines, there is only a need to communicate visual information when I enter the room, other information is gathered empirically (i.e. the weight of the bat is discovered when I lift it). Of course, having discovered an empirical attribute (and assuming it doesn't change) there is no need to have the attribute sent again. Something else I'd like to start a discussion on is the apparent necessity we have of modelling the real world. I believe that so long as the physical laws are apparent, there is no need to extend beyond this (of course, we don't *really* want to accurately model somebody jumping off the golden gate bridge!). Familiar objects are already changing in the real world, push-button phones as opposed to rotary phones, digital display watches as opposed to analogue display. The virtual reality would begin to alter these 'familiar' objects in the same way that digital electronics has already altered the real world examples I've given. I'm currently thinking about what might be the most spectacular changes, but the 'door' argument above is a good enough example to begin with. Comments, opinions? -- --- Mike Moore mike@x.co.uk or mike@ixi-limited.co.uk Usual and obvious disclaimers... etc