[osg-users] Capturing all visible nodes

[Isaac Wolf]

Hello all,

I've looked everywhere for this, and have tried to piece together examples I've found online, but I am having no luck accomplishing what conceptually seems like a very simple task.

The overall goal is to take all nodes within view and send them to UV space for texture mapping. The only part I can't get down is the first part-capturing all visible nodes within view.

I've read through several posts on this sight (removed links because "You must have 2 posts before you can post URL's/Links.")

But they all end without a real solution. The last one in particular just confuses me:

"Just write a NodeVisitor that has it's traversal mode set to TRAVERSE_ALL_CHILDREN i.e. ..."

But that wasn't the question? It was to get all visible nodes, not ALL nodes?

Either way, I've attempted to implement these codes and more, but I just don't understand the structure of node visitors and callbacks enough to make progress.

For example, one of the posts contained this code that seemed very promising:


Code:

class MyCullCallback : public osg::NodeCallback 
{ 

void operator()(osg::Node* node, osg::NodeVisitor* nv) 
{ 
// osgUtil::CullVisitor* cv = nv->asCullVisitor(); 
osgUtil::CullVisitor* cv = dynamic_cast<osgUtil::CullVisitor*>(nv); 
if (!cv->isCulled(*node)) 
{ 
std::cout << "Node is visible: "<< endl; 
} 

if ( cv->isCulled(*node)) 
{ 

std::cout << "Node is NOT visible: "<<endl; 

} 
traverse(node,nv); 
} 
}; 




I tried the following code along with it, but it just throws an error and freezes.


Code:

			MyCullCallback* cb = new MyCullCallback();
			osg::NodeVisitor* nv = new osg::NodeVisitor();
			//cb->operator()(myGroup, nv);




So how exactly am I supposed to utilize it? Do I have to initialize NodeVisitor with an initial node? If so which do I chose?

If there's anymore information I can give please let me know. I've researched all sorts of frustum culling, node visitors, and manually capturing visible nodes with ray tracing, but I figure there has got to be a simpler way to do this!

Thanks for any and all help,

Isaac

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Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=75507#75507