/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSGUTIL_UPDATEVISITOR
#define OSGUTIL_UPDATEVISITOR 1

#include <osg/NodeVisitor>
#include <osg/Node>
#include <osg/Geode>
#include <osg/Billboard>
#include <osg/LOD>
#include <osg/Switch>
#include <osg/LightSource>
#include <osg/Transform>
#include <osg/Projection>
#include <osg/OccluderNode>

#include <osgUtil/Export>

namespace osgUtil {

/**
 * Basic UpdateVisitor implementation for animating a scene.
 * This visitor traverses the scene graph, calling each nodes appCallback if
 * it exists. 
 */
class OSGUTIL_EXPORT UpdateVisitor : public osg::NodeVisitor
{
    public:

        UpdateVisitor();
        virtual ~UpdateVisitor();

        virtual void reset();

    /** During traversal each type of node calls its callbacks and its children traversed. */
        virtual void apply(osg::Node& node)         { handle_callbacks_and_traverse(node); }
        
        virtual void apply(osg::Geode& node)        { handle_geode_callbacks(node); }
        virtual void apply(osg::Billboard& node)    { handle_geode_callbacks(node); }
        
        virtual void apply(osg::LightSource& node)  { handle_callbacks_and_traverse(node); }
        
        virtual void apply(osg::Group& node)        { handle_callbacks_and_traverse(node); }
        virtual void apply(osg::Transform& node)    { handle_callbacks_and_traverse(node); }
        virtual void apply(osg::Projection& node)   { handle_callbacks_and_traverse(node); }
        virtual void apply(osg::Switch& node)       { handle_callbacks_and_traverse(node); }
        virtual void apply(osg::LOD& node)          { handle_callbacks_and_traverse(node); }
        virtual void apply(osg::OccluderNode& node) { handle_callbacks_and_traverse(node); }


    protected:

//         /** Prevent unwanted copy construction.*/
//         UpdateVisitor(const UpdateVisitor&):osg::NodeVisitor() {}

        /** Prevent unwanted copy operator.*/
        UpdateVisitor& operator = (const UpdateVisitor&) { return *this; }
        
        inline void handle_callbacks(osg::StateSet* stateset)
        {
            if (stateset && stateset->requiresUpdateTraversal())
            {
                stateset->runUpdateCallbacks(this);
            }
        }
        
        inline void handle_callbacks_and_traverse(osg::Node& node)
        {
            handle_callbacks(node.getStateSet());

            osg::NodeCallback* callback = node.getUpdateCallback();
            if (callback) (*callback)(&node,this);
            else if (node.getNumChildrenRequiringUpdateTraversal()>0) traverse(node);
        }

        inline void handle_geode_callbacks(osg::Geode& geode)
        {
            handle_callbacks(geode.getStateSet());

            osg::NodeCallback* callback = geode.getUpdateCallback();
            if (callback) (*callback)(&geode,this);

            // Call the app callbacks on the drawables.
            for(unsigned int i=0;i<geode.getNumDrawables();++i)
            {
                osg::Drawable::UpdateCallback* callback = geode.getDrawable(i)->getUpdateCallback();
                if (callback) callback->update(this,geode.getDrawable(i));
                
                handle_callbacks(geode.getDrawable(i)->getStateSet());
            }
            
            // should we traverse just in case a subclass of Geode adds children??  Won't for now as
            // Geode's arn't designed to have children.
            // traverse(geode);
        }    
};

}

#endif