Description of loading less-detailed scene first...
> Does Inventor or any of the other object description protocols have
> such a hierarchical structure?
Inventor doesn't.
An obvious way of implement this is to have a DelayedLevelOfDetail that
looked something like:
DelayedLevelOfDetail {
higherDetailFile "http://www.sgi.com/objects/FancyChair.iv"
Cube { width 5 depth 5 height 3 }
}
... which would display the Cube initially, but which would replace the
cube with the fancy geometry at the right time ("at the right time" is
a browser issue).
FancyChair.iv could also have DelayedLevelOfDetail nodes in it.
This would place an additional burden on the creator of the files, of
course. And it has the undesireable property of storing what is
conceptually one object in multiple files.
If the server is intelligent, it could do some of this automatically--
it could at least deliver up a bounding-box representation of the scene
first. However, once of the nice properties of HTTP is that the server
doesn't care what kind of files it is serving up to the HTTP clients.
If all you care about is rendering speed (and not the length of time to
transfer scenes across the net), then browsers can do this
automatically (Inventor's viewers already support the notion of "render
as bounding boxes", for example).