Re: Up, Coordinates, and Gravity

Randy Stiles (stiles@aic.lockheed.com)
Mon, 11 Dec 95 20:14:03 PST


Ah, the notorious UP Problem crops its head up again...

From: "Gavin Bell" <gavin@krypton.engr.sgi.com>
Date: Mon, 11 Dec 1995 18:42:42 -0800

Please: if we want our worlds to plug together, we all need to agree on
which way is UP.

I DON'T REALLY CARE WHAT WAS CHOSEN. I just care that there be a standard
and that people agree to abide by that standard, so people can say:

It is very important as worlds are linked together that a basic notion
of UP is preserved, and used in common, as Gavin maintains above. Its
too much of a kluge to have to edit files to es-orient other settings,
and doesn't go very well with dynamically assembling a couple of
worlds together.

There is also the issue for updates from independent entities (avatars,
what have you) over the network that are not rooted to some translated
scene graph or world.

So - even though I raised this issue earlier and still believe Z
should be up, we have settled on Y is up, and should follow theough
with it, and everyone should make sure the worlds they build are
consistent with this.

Separator {
Separator {
Transform { ... }
WWWInline { name "http://...yourWorld.wrl" }
}
Separator {
Transform { ... }
WWWInline { name "http://...somebodyElsesWorld.wrl" }
}
}

Yes, I can put scales in the Transform if you didn't happen to model your
world in meters. And yes I can put in a rotation if you decided to ignore
the standard and define something other than Y as up.

But that's really annoying after you've done it for the 115'th time.

So, please please please: fix your translation programs to produce Y==UP,
1 unit == 1 meter worlds.

// Randy Stiles stiles@aic.lockheed.com Orgn 9620 Bldg 255
// 415.354.5256 fax: 415.354.5235 3251 Hanover Street
// Lockheed Martin Palo Alto Research Labs Palo Alto, CA 94304-1191
// http://hitchhiker.space.lockheed.com/~stiles/HOME.html


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