[x3d-public] Pixar animation and OpenUSD (for the Metaverse) startTime

[John Carlson]

It seems like Pixar's USD or OpenUSD might have a problem with startTime,
but I haven't looked at the spec yet.  Start time is the start of the
movie, right, which is the same time for everyone in the theatre, but some
people are late. What about distributed Video-on-Demand or the Metaverse?
When is the startTime for that?

That's why there's ProximitySensors and TouchSensors!  Each person can have
a separate animation! Animation should be under control of
humans interacting with the scene.

More background and historical background.

Alan Kay's Croquet/OpenCroquet/OpenCobalt (now https://croquet.io/) had a
unique way to do timing in a distributed fashion, based on David Reed's PhD
thesis, at least it appears to be him--I don't have a link to the thesis
that I could find.  I did not ever really test in a multiuser fashion, so
don't quote me. I think the SmallTalk code has been converted over to
JavaScript now, probably using Lessons Learned from Lively Kernel.
https://en.wikipedia.org/wiki/Lively_Kernel
(You know, the Dan Ingalls guy).  Sorry if all my information is 10 years
old!

"Each object is aware of, and in direct control, of its behavior in time.
Open Cobalt also directly supports replication of computation, allowing
computation to be moved close to the point of interaction on demand, while
maintaining a consistent view of behaviors that can scale to include
thousands of nodes. It does this by using a combination of object semantics
along with a modified version of David P. Reed
<https://en.wikipedia.org/wiki/David_P._Reed>'s TeaTime peer-based
messaging protocol as a distributed message transactional system enabling
replicated computation (synchronization) across multiple peers.[6]
<https://en.wikipedia.org/wiki/Open_Cobalt#cite_note-6> This makes
replicated computation as easily as replicating data - and makes
synchronization of all events across multiple peers a fundamental property
of the system."

I'm guessing DIS also has a concept of time separate from the person just
joining.

You don't want to restart an animation just because someone just joined,
right?
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