Re: about distinguish nodes

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Marcus Barnes (marcus++at++multigen.com)
Wed, 27 Aug 1997 10:14:35 -0700

On Aug 26, 1:40am, czg++at++iname.com wrote:
> In my performer program I want to seperate some Geodes from others
> ( they are all in ONE scene file ) so that some operations can be
> performed to on(e) part of Geodes and other Geodes not affected.

The phrases "separate geodes" and "part of geodes" imply that you are really
trying to manipulate pfGeoSet and pfGeoState objects. pfGeode's are _always_
distinct nodes in the scene graph after all.

Separating geometry into geodes is simply a matter of hierarchical modeling. In
MultiGen, simply create separate group or object beads and model some faces
under (as children) one object (or group) and some under another.

Note that separating geometry by hierarchy doesn't mean that their appearance
or graphics state (pfGeoState) is separate.

> The operations include: paste terrain clip texture to terrain Geodes
> and not building Geodes;

pfClipTexture's are not bound to pfGeode's per se, they are bound to
pfGeoState's. pfGeoState's are bound to pfGeoSet's which are bound to
pfGeode's. High performance rendering requires that geostates be shared between
as many "identical" geosets as possible. The OpenFlight loader spends much of
its time optimizing geostate sharing. State that is initially shared cannot be
easily unshared at runtime.

> But all Geodes are same type(pfGeode). In Multigen(used to make scene
> database) each node can have 2 user defined fields. These fields can
> be used to identify some specific nodes. But these fields can not be
> read in performer.

Correct. OpenFlight attributes that do not map to Performer attributes are not
part of the collating criteria use by the loader to separate geometry, by
graphics state, in the scene graph.

> How to distinguish nodes of the same type ?

Would you be interested in having the OpenFlight loader extend pfGeoState to
include new attributes, say face DFAD FID and SMC, and include them as sort
criteria?

Regards.

--
+ Marcus Barnes, Technical Staff        mailto:marcus++at++multigen.com +
+ Multigen Inc.                         http://www.multigen.com    +
+ 550 S. Winchester Blvd.               phoneto:1-408-556-2654     +
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