Re: Text Proposal

steve ([email protected])
Thu, 27 Apr 1995 10:08:25 GMT0BST


> But again, that would be overloading the functionality of the Separator
> node. It would be better to have an Annotation node which, like the
> Separator, is a group node with the behavior that its children all face
> the camera. As Gavin has stated, we really need to consider 3 issues when
> we discuss annotation: depth buffer (do annotations appear on top of
> everything?), object size (do objects stay the same size as you move
> closer?), and orientation (do objects always face the camera?).

But why have another node that is similar to the Separator, but
slightly different? Seems a waste of parsing effort to me, and just
makes things more complex.

I think there are two issues

1) annotation - this is text (maybe should be generalized into any
geometry) which always follows the viewpoint, and has some scaling
and hidden surface rules - you can get around the z-buffer problems
by drawing any annotation objects last (and switching the z-buffer
off). Annotation is a special effect required in some applications
where some description, normally textual, is required
2) auto-facing objects - these just follow the user. They are
treated like all other object in the rendering pass - they are
z-buffered etc. and drawn to a fixed scale.

I get the feeling the issue here is that Inventor doesn't support
this - is this the case?

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Steve Ghee ( [email protected] )
Director of Technology

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