[osg-users] How to get the list of triangles of a loaded

[Jerome Hummel]

Thank you Yuen!

 

That's exactly what I was searching for. I am going to try it.

 

Jerome

 

Message: 16

Date: Wed, 30 Apr 2008 10:03:04 -0600

From: "Helbig, Yuen" <Yuen_Helbig at mentor.com>

Subject: Re: [osg-users] How to get the list of triangles of a loaded

      model ?

To: "OpenSceneGraph Users" <osg-users at lists.openscenegraph.org>

Message-ID:

      <16B48DDE4A549643A414C57266A892FAFF71BD at na2-mail.mgc.mentorg.com>

Content-Type: text/plain;    charset="us-ascii"

 

You need to create a derived class from NodeVisitor, and process each

Geode you encounter.  Something like:

 

class GeomInspector : public osg::NodeVisitor

{

...

Constructors, transformMatrix, Array of triangles found, etc...

...

 

////////// Member Functions /////////

 

// If visiting a geode, process it

void apply( osg::Geode& geode )

{

      // I'm still trying to figure out how to correctly pull the

triangles from a Geometry

      // It's something like this

      for( int i = 0; i < geode.getNumDrawables(); i++)

      {

            osg::Geometry* tempGeometry =

tempGeode.geode->getDrawable(i)->asGeometry();

            ?

            ?

            ?

            // don't forget to apply the correct matrix transform to

the triangle you find

      }

 

      geode.traverse(*this);

}

 

// If we are visiting a matrix transform node, accumulate the transform

void GeomInspector::apply( osg::MatrixTransform& new_transformMatrix )

{

      transformMatrix.preMult(new_transformMatrix.getMatrix());

 

      new_transformMatrix.traverse(*this);

}

 

// If we are visiting any other type of node, keep going. 

virtual void apply( osg::Node& node )

{

      node.traverse(*this);

}

 

};

 

 

Using the a NodeVisitor goes like this:

 

 

GeomInspector gm;

root->accept(gm); // root is the top level of your Scene Graph

 

 

I'm using an older version of OSG, but I hope this gives you some

insight.

 

________________________________

 

From: osg-users-bounces at lists.openscenegraph.org

[mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Jerome

Hummel

Sent: Wednesday, April 30, 2008 5:48 AM

To: osg-users at lists.openscenegraph.org

Subject: [osg-users] How to get the list of triangles of a loaded model

?

 

 

 

Hi,

 

 

 

I was wondering how I could get the list of triangles (and rendering

order tr1, tr2, ...) of a loaded model ?

 

Is there any way to do that with openscenegraph ? Some sort of scene

graph traversal action providing a callback for each encountered

triangle in their order of rendering (without actually rendering

anything).

 

Can anybody tell me how to realize that or point out something in the

doc ?

 

Any help would be greatly appreciated!

 

Many thanks !

 

 

 

Jerome Hummel

 

 

 

 

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