[osg-users] [About VertexArrayObject Branch] FeedBack and Insight

[Jannik Heller]

Hi,

please correct me if I'm wrong (I have a naive understanding of VAO). I don't see the point of VAO sharing. If a VAO can be "shared" between two Geometries, that means the Geometries have the same set of vertex arrays, correct? So then why use two separate Geometries to begin with if they are identical? You can re-use a Geometry by attaching it to multiple parents.

The only downside I could think of when re-using a Geometry is that a Node with more than one parent can cause problems (certain functions like getWorldMatrices() suddenly return multiple results). Or you might want to assign a different StateSet to each copy of the Geometry (but in that case you could decorate the Geometry with an intermediate node and set the StateSet there).

I guess this might be a case where the pre-OSG3.4 way of having a Geometry attached to a Geode instead of directly into the scene graph makes more sense. That way doing Geometry sharing doesn't result in a multi-parented graph...

Cheers,
Jannik

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http://forum.openscenegraph.org/viewtopic.php?p=68390#68390