Re: Scenes with lots of simple objects

Len Wanger ([email protected])
Tue, 7 Mar 1995 11:45:09 -0800 (PST)

> On Feb 28, 9:04am, Scott Nelson wrote:
> > I'd appreciate any feedback on the following:
....
>
> Even if given hints, what would a viewer do with those hints? I don't know
> how to write a general viewer that can render 50*50*50 cubes quickly.
>
> I think it makes more sense to define new kinds of shapes that know how to
> render large numbers of simple primitives, and that know how to optimize the
> rendering. For example, a CubeSet could store the cubes in a spacial data
> structure, figure out where the eyepoint is relative to the cubes, draw them
> back to front, and (if it was really smart) avoid drawing invisible cubes.

Scott's example does raise an important issue. OpenInventor supports a
particular graphics paradigm - local rendering of surface data. There
are lots of data-sets out there that do not fit nicely into this
paradigm. For instance, Scott's cubes example fits more nicely in a
volume rendering paradigm.

If VRML supported volumes as a primitive, the data could be represented
more compactly, and an implementation, perhaps using inventor, could
also take advantage of all sorts of rendering tricks to speed up
performance (such as those described in Brian Kabral's work.)

Due to the difficulty of the undertaking, I do not propose that VRML
takes on volume rendering, but it is important to acknowledge the fact
that the primitives supported by VRML are not optimal for everybody's
data.

Len Wanger -- [email protected]
Project Sequoia 2000
San Diego Supercomputer Center