/* -*-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.
*/

#include <osg/GLExtensions>
#include <osgUtil/GLObjectsVisitor>
#include <osgGA/TrackballManipulator>
#include <osgViewer/Viewer>

#include <osg/io_utils>

using namespace osgViewer;

Viewer::Viewer():
    _firstFrame(true),
    _done(false),
    _keyEventSetsDone(osgGA::GUIEventAdapter::KEY_Escape),
    _quitEventSetsDone(true),
    _threadingModel(ThreadPerContext),
    _endBarrierPosition(AfterSwapBuffers),
    _numThreadsOnBarrier(0)
{
    _frameStamp = new osg::FrameStamp;
    _frameStamp->setFrameNumber(0);
    _frameStamp->setReferenceTime(0);
    _frameStamp->setSimulationTime(0);

    _eventVisitor = new osgGA::EventVisitor;
    _eventVisitor->setActionAdapter(this);
    
    setStats(new osg::Stats("Viewer"));
}

Viewer::~Viewer()
{
    //osg::notify(osg::NOTICE)<<"Viewer::~Viewer()"<<std::endl;

    stopThreading();
    
    if (_scene.valid() && _scene->getDatabasePager())
    {
        _scene->getDatabasePager()->cancel();
        _scene->setDatabasePager(0);
    }

    Contexts contexts;
    getContexts(contexts);

    // clear out all the previously assigned operations
    for(Contexts::iterator citr = contexts.begin();
        citr != contexts.end();
        ++citr)
    {
        (*citr)->close();
    }

    //osg::notify(osg::NOTICE)<<"finish Viewer::~Viewer()"<<std::endl;
    
}

bool Viewer::isRealized() const
{

    Contexts contexts;
    const_cast<Viewer*>(this)->getContexts(contexts);

    unsigned int numRealizedWindows = 0;

    // clear out all the previously assigned operations
    for(Contexts::iterator citr = contexts.begin();
        citr != contexts.end();
        ++citr)
    {
        if ((*citr)->isRealized()) ++numRealizedWindows;
    }
    
    return numRealizedWindows > 0;
}

int Viewer::run()
{
    // if we don't have any scene graph assigned then just return
    if (!getSceneData())
    {
        osg::notify(osg::NOTICE)<<"Warning: Viewer::run() called without a scene graph being assigned to the viewer, cannot run."<<std::endl;
        return 1;
    }

    if (!getCameraManipulator())
    {
        setCameraManipulator(new osgGA::TrackballManipulator());
    }

    if (!isRealized())
    {
        realize();
    }

    while (!done())
    {
        frame();
    }
    
    return 0;
}

void Viewer::setStartTick(osg::Timer_t tick)
{
    _startTick = tick;
    
    Contexts contexts;
    getContexts(contexts,false);

    getEventQueue()->setStartTick(_startTick);
    for(Contexts::iterator citr = contexts.begin();
        citr != contexts.end();
        ++citr)
    {
        osgViewer::GraphicsWindow* gw = dynamic_cast<osgViewer::GraphicsWindow*>(*citr);
        if (gw)
        {
            gw->getEventQueue()->setStartTick(_startTick);
        }
    }
}


void Viewer::setReferenceTime(double time)
{
    osg::Timer_t tick = osg::Timer::instance()->tick();
    double currentTime = osg::Timer::instance()->delta_s(_startTick, tick);
    double delta_ticks = (time-currentTime)*(osg::Timer::instance()->getSecondsPerTick());
    if (delta_ticks>=0) tick += osg::Timer_t(delta_ticks);
    else tick -= osg::Timer_t(-delta_ticks);

    // assign the new start tick
    setStartTick(tick);
}


void Viewer::setSceneData(osg::Node* node)
{
    _scene = new osgViewer::Scene;
    _scene->setSceneData(node);
    _scene->setFrameStamp(_frameStamp.get());
    
    setReferenceTime(0.0);
    
    assignSceneDataToCameras();
    setUpRenderingSupport();
}

void Viewer::setThreadingModel(ThreadingModel threadingModel)
{
    if (_threadingModel == threadingModel) return;
    
    if (_threadingModel!=SingleThreaded) stopThreading();
    
    _threadingModel = threadingModel;

    if (_threadingModel!=SingleThreaded) startThreading();
}

void Viewer::setUseMainThreadForRenderingTraversals(bool flag)
{
    if (_useMainThreadForRenderingTraversal==flag) return;

    if (_threadingModel!=SingleThreaded) stopThreading();
    
    _useMainThreadForRenderingTraversal = flag;
    
    if (_threadingModel!=SingleThreaded) startThreading();
}

void Viewer::setEndBarrierPosition(BarrierPosition bp)
{
    if (_endBarrierPosition == bp) return;
    
    if (_threadingModel!=SingleThreaded) stopThreading();
    
    _endBarrierPosition = bp;

    if (_threadingModel!=SingleThreaded) startThreading();
}

void Viewer::stopThreading()
{
    if (_numThreadsOnBarrier==0) return;

    osg::notify(osg::INFO)<<"Viewer::stopThreading() - stopping threading"<<std::endl;

    Contexts contexts;
    getContexts(contexts);

    // delete all the graphics threads.    
    for(Contexts::iterator itr = contexts.begin();
        itr != contexts.end();
        ++itr)
    {
        (*itr)->setGraphicsThread(0);
    }

    _startRenderingBarrier = 0;
    _endRenderingDispatchBarrier = 0;
    _numThreadsOnBarrier = 0;
}

// Compile operation, that compile OpenGL objects.
struct ViewerCompileOperation : public osg::GraphicsOperation
{
    ViewerCompileOperation(osg::Node* scene):
        osg::GraphicsOperation("Compile",false),
        _scene(scene)
    {
    }
    
    virtual void operator () (osg::GraphicsContext* context)
    {
        // OpenThreads::ScopedLock<OpenThreads::Mutex> lock(mutex);
        // osg::notify(osg::NOTICE)<<"Compile "<<context<<" "<<OpenThreads::Thread::CurrentThread()<<std::endl;

        // context->makeCurrentImplementation();

        osgUtil::GLObjectsVisitor compileVisitor;
        compileVisitor.setState(context->getState());

        // do the compile traversal
        if (_scene.valid()) _scene->accept(compileVisitor);

        // osg::notify(osg::NOTICE)<<"Done Compile "<<context<<" "<<OpenThreads::Thread::CurrentThread()<<std::endl;
    }
    
    osg::ref_ptr<osg::Node> _scene;
};


// Draw operation, that does a draw on the scene graph.
struct ViewerRunOperations : public osg::GraphicsOperation
{
    ViewerRunOperations():
        osg::GraphicsOperation("RunOperation",true)
    {
    }
    
    virtual void operator () (osg::GraphicsContext* gc)
    {
        gc->runOperations();
    }
};

unsigned int Viewer::computeNumberOfThreadsIncludingMainRequired()
{
    Contexts contexts;
    getContexts(contexts);

    if (contexts.empty()) return 0;

    if (contexts.size()==1 || _threadingModel==SingleThreaded)
    {
        return 1;
    }

    return _useMainThreadForRenderingTraversal ? contexts.size() : contexts.size()+1;
}

void Viewer::startThreading()
{
    unsigned int numThreadsIncludingMainThread = computeNumberOfThreadsIncludingMainRequired();

    // return if we don't need multiple threads.
    if (numThreadsIncludingMainThread <= 1) return;
    
    // return if threading is already up and running
    if (numThreadsIncludingMainThread == _numThreadsOnBarrier) return;
    
    if (_numThreadsOnBarrier!=0) 
    {
        // we already have threads running but not the right number, so stop them and then create new threads.
        stopThreading();
    }

    osg::notify(osg::INFO)<<"Viewer::startThreading() - starting threading"<<std::endl;

    // using multi-threading so make sure that new objects are allocated with thread safe ref/unref
    osg::Referenced::setThreadSafeReferenceCounting(true);
    
    if (getSceneData())
    {
        osg::notify(osg::INFO)<<"Making scene thread safe"<<std::endl;

        // make sure that existing scene graph objects are allocated with thread safe ref/unref
        getSceneData()->setThreadSafeRefUnref(true);
        
        // update the scene graph so that it has enough GL object buffer memory for the graphics contexts that will be using it.
        getSceneData()->resizeGLObjectBuffers(osg::DisplaySettings::instance()->getMaxNumberOfGraphicsContexts());
    }


    Contexts contexts;
    getContexts(contexts);

    int numProcessors = OpenThreads::GetNumberOfProcessors();
    bool affinity = true;
    
    bool firstContextAsMainThread = numThreadsIncludingMainThread==contexts.size();

    // osg::notify(osg::NOTICE)<<"numThreadsIncludingMainThread=="<<numThreadsIncludingMainThread<<std::endl;

    _numThreadsOnBarrier = numThreadsIncludingMainThread;
    _startRenderingBarrier = new osg::BarrierOperation(_numThreadsOnBarrier, osg::BarrierOperation::NO_OPERATION);


    if (_threadingModel==ThreadPerContext)
    {
    #if 1
        _endRenderingDispatchBarrier = new osg::BarrierOperation(_numThreadsOnBarrier, osg::BarrierOperation::NO_OPERATION);
    #else    
        _endRenderingDispatchBarrier = new osg::BarrierOperation(_numThreadsOnBarrier, osg::BarrierOperation::GL_FINISH);
    #endif
    }
    else
    {
        _endDynamicDrawBlock = new EndOfDynamicDrawBlock;
    }

    osg::ref_ptr<osg::SwapBuffersOperation> swapOp = new osg::SwapBuffersOperation();

    Contexts::iterator citr = contexts.begin(); 
    unsigned int processNum = 0;

    if (firstContextAsMainThread)
    {
        ++processNum;
        ++citr;
    }


    for(;
        citr != contexts.end();
        ++citr,
        ++processNum)
    {
        osg::GraphicsContext* gc = (*citr);
        
        gc->getState()->setDynamicObjectRenderingCompletedCallback(_endDynamicDrawBlock.get());

        // create the a graphics thread for this context
        gc->createGraphicsThread();

        if (affinity) gc->getGraphicsThread()->setProcessorAffinity(processNum % numProcessors);

        gc->getGraphicsThread()->add(new ViewerCompileOperation(getSceneData()));

        // add the startRenderingBarrier
        gc->getGraphicsThread()->add(_startRenderingBarrier.get());

        // add the rendering operation itself.
        gc->getGraphicsThread()->add(new ViewerRunOperations());

        if (_endBarrierPosition==BeforeSwapBuffers && _endRenderingDispatchBarrier.valid())
        {
            // add the endRenderingDispatchBarrier
            gc->getGraphicsThread()->add(_endRenderingDispatchBarrier.get());
        }

        // add the swap buffers
        gc->getGraphicsThread()->add(swapOp.get());

        if (_endBarrierPosition==AfterSwapBuffers && _endRenderingDispatchBarrier.valid())
        {
            // add the endRenderingDispatchBarrier
            gc->getGraphicsThread()->add(_endRenderingDispatchBarrier.get());
        }

    }

    if (firstContextAsMainThread)
    {
        if (affinity) OpenThreads::SetProcessorAffinityOfCurrentThread(0);
    }

    for(citr = contexts.begin();
        citr != contexts.end();
        ++citr)
    {
        osg::GraphicsContext* gc = (*citr);
        if (gc->getGraphicsThread() && !gc->getGraphicsThread()->isRunning())
        {
            //osg::notify(osg::NOTICE)<<"  gc->getGraphicsThread()->startThread() "<<gc->getGraphicsThread()<<std::endl;
            gc->getGraphicsThread()->startThread();
            // OpenThreads::Thread::YieldCurrentThread();
        }
    }
}

void Viewer::checkWindowStatus()
{
    unsigned int numThreadsIncludingMainThread = computeNumberOfThreadsIncludingMainRequired();
    if (numThreadsIncludingMainThread != _numThreadsOnBarrier)
    {
        stopThreading();
        
        if (numThreadsIncludingMainThread > 1) startThreading();
    }
    
    if (numThreadsIncludingMainThread==0) _done = true;
}


void Viewer::getContexts(Contexts& contexts, bool onlyValid)
{
    typedef std::set<osg::GraphicsContext*> ContextSet;
    ContextSet contextSet;

    if (_camera.valid() && 
        _camera->getGraphicsContext() && 
        (_camera->getGraphicsContext()->valid() || !onlyValid))
    {
        contextSet.insert(_camera->getGraphicsContext());
    }
    
    for(unsigned int i=0; i<getNumSlaves(); ++i)
    {
        Slave& slave = getSlave(i);
        if (slave._camera.valid() && 
            slave._camera->getGraphicsContext() && 
            (slave._camera->getGraphicsContext()->valid() || !onlyValid))
        {
            contextSet.insert(slave._camera->getGraphicsContext());
        }
    }

    contexts.clear();
    contexts.reserve(contextSet.size());

    for(ContextSet::iterator itr = contextSet.begin();
        itr != contextSet.end();
        ++itr)
    {
        contexts.push_back(const_cast<osg::GraphicsContext*>(*itr));
    }
}

void Viewer::getWindows(Windows& windows, bool onlyValid)
{
    windows.clear();

    Contexts contexts;
    getContexts(contexts, onlyValid);
    
    for(Contexts::iterator itr = contexts.begin();
        itr != contexts.end();
        ++itr)
    {
        osgViewer::GraphicsWindow* gw = dynamic_cast<osgViewer::GraphicsWindow*>(*itr);
        if (gw) windows.push_back(gw);
    }
}

// Draw operation, that does a draw on the scene graph.
struct ViewerRenderingOperation : public osg::GraphicsOperation
{
    ViewerRenderingOperation(osgUtil::SceneView* sceneView, osgDB::DatabasePager* databasePager, osg::Timer_t startTick):
        osg::GraphicsOperation("Render",true),
        _sceneView(sceneView),
        _databasePager(databasePager),
        _startTick(startTick),
        _initialized(false),
        _aquireGPUStats(false),
        _extensions(0)
    {
        _sceneView->getCullVisitor()->setDatabaseRequestHandler(_databasePager.get());
    }
    
    typedef std::pair<GLuint, int> QueryFrameNumberPair;
    typedef std::list<QueryFrameNumberPair> QueryFrameNumberList;
    typedef std::vector<GLuint> QueryList;

    inline void checkQuery(osg::Stats* stats)
    {
        for(QueryFrameNumberList::iterator itr = _queryFrameNumberList.begin();
            itr != _queryFrameNumberList.end();
            )
        {
            GLuint query = itr->first;
            GLint available = 0;
            _extensions->glGetQueryObjectiv(query, GL_QUERY_RESULT_AVAILABLE, &available);
            if (available)
            {
                GLuint64EXT timeElapsed = 0;
                _extensions->glGetQueryObjectui64v(query, GL_QUERY_RESULT, &timeElapsed);

                double timeElapsedSeconds = double(timeElapsed)*1e-9;
                double currentTime = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());
                double estimatedEndTime = (_previousQueryTime + currentTime) * 0.5;
                double estimatedBeginTime = estimatedEndTime - timeElapsedSeconds;

                stats->setAttribute(itr->second, "GPU draw begin time", estimatedBeginTime);
                stats->setAttribute(itr->second, "GPU draw end time", estimatedEndTime);
                stats->setAttribute(itr->second, "GPU draw time taken", timeElapsedSeconds);
                

                itr = _queryFrameNumberList.erase(itr);
                _availableQueryObjects.push_back(query);
            }
            else
            {
                ++itr;
            }
            
        }
        _previousQueryTime = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());
    }
    
    inline GLuint createQueryObject()
    {
        if (_availableQueryObjects.empty())
        {
            GLuint query;
            _extensions->glGenQueries(1, &query);
            return query;
        }
        else
        {
            GLuint query = _availableQueryObjects.back();
            _availableQueryObjects.pop_back();
            return query;
        }
    }
    
    inline void beginQuery(int frameNumber)
    {
        GLuint query = createQueryObject();
        _extensions->glBeginQuery(GL_TIME_ELAPSED, query);
        _queryFrameNumberList.push_back(QueryFrameNumberPair(query, frameNumber));        
    }
    
    inline void endQuery()
    {
        _extensions->glEndQuery(GL_TIME_ELAPSED);
    }
    
    virtual void operator () (osg::GraphicsContext*)
    {
        if (!_sceneView) return;

        // osg::notify(osg::NOTICE)<<"RenderingOperation"<<std::endl;

        osg::Stats* stats = _sceneView->getCamera()->getStats();
        osg::State* state = _sceneView->getState();
        const osg::FrameStamp* fs = state->getFrameStamp();
        int frameNumber = fs ? fs->getFrameNumber() : 0;

        if (!_initialized)
        {
            _initialized = true;
            _extensions = stats ? osg::Drawable::getExtensions(state->getContextID(),true) : 0;
            _aquireGPUStats = _extensions && _extensions->isTimerQuerySupported();
            _previousQueryTime = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());
        }
        
//        _aquireGPUStats = false;


        if (_aquireGPUStats) 
        {
            checkQuery(stats);
        }
        
        // do cull taversal
        osg::Timer_t beforeCullTick = osg::Timer::instance()->tick();
        _sceneView->cull();
        osg::Timer_t afterCullTick = osg::Timer::instance()->tick();

        if (state->getDynamicObjectCount()==0 && state->getDynamicObjectRenderingCompletedCallback())
        {
            state->getDynamicObjectRenderingCompletedCallback()->completed(state);
        }

        // do draw traveral
        if (_aquireGPUStats) 
        {
            checkQuery(stats);
            beginQuery(frameNumber);
        }
                
        _sceneView->draw();

        double availableTime = 0.004; // 4 ms
        if (_databasePager.valid())
        {
            _databasePager->compileGLObjects(*(_sceneView->getState()), availableTime);
        }
        _sceneView->flushDeletedGLObjects(availableTime);

        if (_aquireGPUStats)
        {
            endQuery();
            checkQuery(stats);
        }
        
        osg::Timer_t afterDrawTick = osg::Timer::instance()->tick();
        

        if (stats)
        {
            stats->setAttribute(frameNumber, "Cull traversal begin time", osg::Timer::instance()->delta_s(_startTick, beforeCullTick));
            stats->setAttribute(frameNumber, "Cull traversal end time", osg::Timer::instance()->delta_s(_startTick, afterCullTick));
            stats->setAttribute(frameNumber, "Cull traversal time taken", osg::Timer::instance()->delta_s(beforeCullTick, afterCullTick));

            stats->setAttribute(frameNumber, "Draw traversal begin time", osg::Timer::instance()->delta_s(_startTick, afterCullTick));
            stats->setAttribute(frameNumber, "Draw traversal end time", osg::Timer::instance()->delta_s(_startTick, afterDrawTick));
            stats->setAttribute(frameNumber, "Draw traversal time taken", osg::Timer::instance()->delta_s(afterCullTick, afterDrawTick));
        }
        
    }
    
    osg::observer_ptr<osgUtil::SceneView>       _sceneView;
    osg::observer_ptr<osgDB::DatabasePager>     _databasePager;

    osg::Timer_t                                _startTick;
    
    bool                                        _initialized;
    bool                                        _aquireGPUStats;
    const osg::Drawable::Extensions*            _extensions;
    QueryFrameNumberList                        _queryFrameNumberList;
    QueryList                                   _availableQueryObjects;
    double                                      _previousQueryTime;
};

void Viewer::setUpRenderingSupport()
{
#if 1
    _cameraSceneViewMap.clear();

    Contexts contexts;
    getContexts(contexts);
    
    osg::FrameStamp* frameStamp = getFrameStamp();
    osg::DisplaySettings* ds = _displaySettings.valid() ? _displaySettings.get() : osg::DisplaySettings::instance();
    osgDB::DatabasePager* dp = _scene.valid() ? _scene->getDatabasePager() : 0;

    for(Contexts::iterator gcitr = contexts.begin();
        gcitr != contexts.end();
        ++gcitr)
    {
        (*gcitr)->removeAllOperations();

        osg::GraphicsContext* gc = *gcitr;
        osg::GraphicsContext::Cameras& cameras = gc->getCameras();
        osg::State* state = gc->getState();
        
        for(osg::GraphicsContext::Cameras::iterator citr = cameras.begin();
            citr != cameras.end();
            ++citr)
        {
            osg::Camera* camera = *citr;
            
            camera->setStats(new osg::Stats("Camera"));

            osgUtil::SceneView* sceneView = new osgUtil::SceneView;
            _cameraSceneViewMap[camera] = sceneView;

            sceneView->setGlobalStateSet(_camera->getStateSet());
            sceneView->setDefaults();
            sceneView->setDisplaySettings(ds);
            sceneView->setCamera(camera);
            sceneView->setState(state);
            sceneView->setFrameStamp(frameStamp);

            if (dp) dp->setCompileGLObjectsForContextID(state->getContextID(), true);

            gc->add(new ViewerRenderingOperation(sceneView, dp, _startTick));
            
        }
    }

#else
    _cameraSceneViewMap.clear();

    Contexts contexts;
    getContexts(contexts);
    
    osg::FrameStamp* frameStamp = getFrameStamp();
    osg::DisplaySettings* ds = _displaySettings.valid() ? _displaySettings.get() : osg::DisplaySettings::instance();
    osgDB::DatabasePager* dp = _scene.valid() ? _scene->getDatabasePager() : 0;

    // clear out all the previously assigned operations
    for(Contexts::iterator gcitr = contexts.begin();
        gcitr != contexts.end();
        ++gcitr)
    {
        (*gcitr)->removeAllOperations();
    }

    if (_camera.valid() && _camera->getGraphicsContext())
    {
        _camera->setStats(new osg::Stats("Camera"));

        osgUtil::SceneView* sceneView = new osgUtil::SceneView;
        _cameraSceneViewMap[_camera] = sceneView;

        sceneView->setGlobalStateSet(_camera->getStateSet());
        sceneView->setDefaults();
        sceneView->setDisplaySettings(ds);
        sceneView->setCamera(_camera.get());
        sceneView->setState(_camera->getGraphicsContext()->getState());
        sceneView->setSceneData(getSceneData());
        sceneView->setFrameStamp(frameStamp);
        
        if (dp) dp->setCompileGLObjectsForContextID(_camera->getGraphicsContext()->getState()->getContextID(), true);

        _camera->getGraphicsContext()->add(new ViewerRenderingOperation(sceneView, dp));        
    }
    
    for(unsigned i=0; i<getNumSlaves(); ++i)
    {
        Slave& slave = getSlave(i);
        if (slave._camera.valid() && slave._camera->getGraphicsContext())
        {
            _camera->setStats(new osg::Stats("Slave Camera"));

            osgUtil::SceneView* sceneView = new osgUtil::SceneView;
            _cameraSceneViewMap[slave._camera] = sceneView;

            sceneView->setGlobalStateSet(_camera->getStateSet());
            sceneView->setDefaults();
            sceneView->setCamera(slave._camera.get());
            sceneView->setDisplaySettings(ds);
            sceneView->setState(slave._camera->getGraphicsContext()->getState());
            sceneView->setSceneData(getSceneData());
            sceneView->setFrameStamp(frameStamp);

            if (dp) dp->setCompileGLObjectsForContextID(slave._camera->getGraphicsContext()->getState()->getContextID(), true);

            slave._camera->getGraphicsContext()->add(new ViewerRenderingOperation(sceneView, dp));
        }
    }
#endif
}


void Viewer::realize()
{
    //osg::notify(osg::INFO)<<"Viewer::realize()"<<std::endl;
    
    setCameraWithFocus(0);

    Contexts contexts;
    getContexts(contexts);
    
    if (contexts.empty())
    {
        osg::notify(osg::INFO)<<"Viewer::realize() - No valid contexts found, setting up view across all screens."<<std::endl;
    
        // no windows are already set up so set up a default view        
        setUpViewAcrossAllScreens();
        getContexts(contexts);
    }

    if (contexts.empty())
    {
        osg::notify(osg::NOTICE)<<"Viewer::realize() - failed to set up any windows"<<std::endl;
        _done = true;
        return;
    }
    
    setUpRenderingSupport();
    
    for(Contexts::iterator citr = contexts.begin();
        citr != contexts.end();
        ++citr)
    {
        osg::GraphicsContext* gc = *citr;
        gc->realize();
        
        if (_realizeOperation.valid())
        {
            gc->makeCurrent();
            
            (*_realizeOperation)(gc);
            
            gc->releaseContext();
        }
    }
    
    bool grabFocus = true;
    if (grabFocus)
    {
        for(Contexts::iterator citr = contexts.begin();
            citr != contexts.end();
            ++citr)
        {
            osgViewer::GraphicsWindow* gw = dynamic_cast<osgViewer::GraphicsWindow*>(*citr);
            if (gw)
            {
                gw->grabFocusIfPointerInWindow();    
            }
        }
    }
    
    // initialize the global timer to be relative to the current time.
    osg::Timer::instance()->setStartTick();

    // pass on the start tick to all the associated eventqueues
    setStartTick(osg::Timer::instance()->getStartTick());

    startThreading();

}


void Viewer::frame(double simulationTime)
{
    if (_done) return;

    // osg::notify(osg::NOTICE)<<std::endl<<"Viewer::frame()"<<std::endl<<std::endl;

    if (_firstFrame)
    {
        init();
        
        if (!isRealized())
        {
            realize();
        }
        
        _firstFrame = false;
    }
    advance(simulationTime);
    
    eventTraversal();
    updateTraversal();
    renderingTraversals();
}

void Viewer::advance(double simulationTime)
{
    if (_done) return;

    double prevousReferenceTime = _frameStamp->getReferenceTime();
    int previousFrameNumber = _frameStamp->getFrameNumber();

    _frameStamp->setFrameNumber(_frameStamp->getFrameNumber()+1);

    _frameStamp->setReferenceTime( osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick()) );

    if (simulationTime==USE_REFERENCE_TIME)
    {
        _frameStamp->setSimulationTime(_frameStamp->getReferenceTime());
    }
    else
    {
        _frameStamp->setSimulationTime(simulationTime);
    }
    
    if (getStats())
    {
        // update previous frame stats
        double deltaFrameTime = _frameStamp->getReferenceTime() - prevousReferenceTime;
        getStats()->setAttribute(previousFrameNumber, "Frame duration", deltaFrameTime);
        getStats()->setAttribute(previousFrameNumber, "Frame rate", 1.0/deltaFrameTime);

        // update current frames stats
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Reference time", _frameStamp->getReferenceTime());
    }
}

void Viewer::eventTraversal()
{
    if (_done) return;

    double beginEventTraversal = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());

    // osg::notify(osg::NOTICE)<<"Viewer::frameEventTraversal()."<<std::endl;
    
    // need to copy events from the GraphicsWindow's into local EventQueue;
    osgGA::EventQueue::Events events;

    Contexts contexts;
    getContexts(contexts);

    osgGA::GUIEventAdapter* eventState = getEventQueue()->getCurrentEventState(); 
    osg::Matrix masterCameraVPW = getCamera()->getViewMatrix() * getCamera()->getProjectionMatrix();
    if (getCamera()->getViewport()) 
    {
        osg::Viewport* viewport = getCamera()->getViewport();
        masterCameraVPW *= viewport->computeWindowMatrix();
        eventState->setInputRange( viewport->x(), viewport->y(), viewport->x() + viewport->width(), viewport->y() + viewport->height());
    }
    else
    {
        eventState->setInputRange(-1.0, -1.0, 1.0, 1.0);
    }


    for(Contexts::iterator citr = contexts.begin();
        citr != contexts.end();
        ++citr)
    {
        osgViewer::GraphicsWindow* gw = dynamic_cast<osgViewer::GraphicsWindow*>(*citr);
        if (gw)
        {
            gw->checkEvents();
            
            osgGA::EventQueue::Events gw_events;
            gw->getEventQueue()->takeEvents(gw_events);
            
            osgGA::EventQueue::Events::iterator itr;
            for(itr = gw_events.begin();
                itr != gw_events.end();
                ++itr)
            {
                osgGA::GUIEventAdapter* event = itr->get();
                
                bool pointerEvent = false;

                float x = event->getX();
                float y = event->getY();
                
                bool invert_y = event->getMouseYOrientation()==osgGA::GUIEventAdapter::Y_INCREASING_DOWNWARDS;
                if (invert_y && gw->getTraits()) y = gw->getTraits()->height - y;
                
                switch(event->getEventType())
                {
                    case(osgGA::GUIEventAdapter::PUSH):
                    case(osgGA::GUIEventAdapter::RELEASE):
                    case(osgGA::GUIEventAdapter::DRAG):
                    case(osgGA::GUIEventAdapter::MOVE):
                    {
                        pointerEvent = true;
                        
                        if (event->getEventType()!=osgGA::GUIEventAdapter::DRAG || !getCameraWithFocus())
                        {
                            osg::GraphicsContext::Cameras& cameras = gw->getCameras();
                            for(osg::GraphicsContext::Cameras::iterator citr = cameras.begin();
                                citr != cameras.end();
                                ++citr)
                            {
                                osg::Camera* camera = *citr;
                                if (camera->getView()==this)
                                {
                                    osg::Viewport* viewport = camera ? camera->getViewport() : 0;
                                    if (viewport && 
                                        x >= viewport->x() && y >= viewport->y() &&
                                        x <= (viewport->x()+viewport->width()) && y <= (viewport->y()+viewport->height()) )
                                    {
                                        setCameraWithFocus(camera);
                                    }
                                }
                            }
                        }
                        
                        break;
                    }
                    default:
                        break;
                }
                
                if (pointerEvent)
                {
                    if (getCameraWithFocus())
                    {
                        osg::Viewport* viewport = getCameraWithFocus()->getViewport();
                        osg::Matrix localCameraVPW = getCameraWithFocus()->getViewMatrix() * getCameraWithFocus()->getProjectionMatrix();
                        if (viewport) localCameraVPW *= viewport->computeWindowMatrix();

                        osg::Matrix matrix( osg::Matrix::inverse(localCameraVPW) * masterCameraVPW );

                        osg::Vec3d new_coord = osg::Vec3d(x,y,0.0) * matrix;

                        x = new_coord.x();
                        y = new_coord.y();                                

                        event->setInputRange(eventState->getXmin(), eventState->getYmin(), eventState->getXmax(), eventState->getYmax());
                        event->setX(x);
                        event->setY(y);
                        event->setMouseYOrientation(osgGA::GUIEventAdapter::Y_INCREASING_UPWARDS);

                    }
                    // pass along the new pointer events details to the eventState of the viewer 
                    eventState->setX(x);
                    eventState->setY(y);
                    eventState->setButtonMask(event->getButtonMask());
                    eventState->setMouseYOrientation(osgGA::GUIEventAdapter::Y_INCREASING_UPWARDS);

                }
                else
                {
                    event->setInputRange(eventState->getXmin(), eventState->getYmin(), eventState->getXmax(), eventState->getYmax());
                    event->setX(eventState->getX());
                    event->setY(eventState->getY());
                    event->setButtonMask(eventState->getButtonMask());
                    event->setMouseYOrientation(eventState->getMouseYOrientation());
                }
                //osg::notify(osg::NOTICE)<<"   mouse x = "<<event->getX()<<" y="<<event->getY()<<std::endl;
                // osg::notify(osg::NOTICE)<<"   mouse Xmin = "<<event->getXmin()<<" Ymin="<<event->getYmin()<<" xMax="<<event->getXmax()<<" Ymax="<<event->getYmax()<<std::endl;
            }

            for(itr = gw_events.begin();
                itr != gw_events.end();
                ++itr)
            {
                osgGA::GUIEventAdapter* event = itr->get();
                switch(event->getEventType())
                {
                    case(osgGA::GUIEventAdapter::CLOSE_WINDOW):
                    {
                        // stopThreading();
                        
                        gw->close();
                        
                        // startThreading();
                        
                        break;
                    }
                    default:
                        break;
                }
            }

            events.insert(events.end(), gw_events.begin(), gw_events.end());

        }
    }
    

    // osg::notify(osg::NOTICE)<<"mouseEventState Xmin = "<<eventState->getXmin()<<" Ymin="<<eventState->getYmin()<<" xMax="<<eventState->getXmax()<<" Ymax="<<eventState->getYmax()<<std::endl;


    _eventQueue->frame( getFrameStamp()->getReferenceTime() );
    _eventQueue->takeEvents(events);


#if 0
    // osg::notify(osg::NOTICE)<<"Events "<<events.size()<<std::endl;
    for(osgGA::EventQueue::Events::iterator itr = events.begin();
        itr != events.end();
        ++itr)
    {
        osgGA::GUIEventAdapter* event = itr->get();
        switch(event->getEventType())
        {
            case(osgGA::GUIEventAdapter::PUSH):
                osg::notify(osg::NOTICE)<<"  PUSH "<<event->getButton()<<" x="<<event->getX()<<" y="<<event->getY()<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::RELEASE):
                osg::notify(osg::NOTICE)<<"  RELEASE "<<event->getButton()<<" x="<<event->getX()<<" y="<<event->getY()<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::DRAG):
                osg::notify(osg::NOTICE)<<"  DRAG "<<event->getButtonMask()<<" x="<<event->getX()<<" y="<<event->getY()<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::MOVE):
                osg::notify(osg::NOTICE)<<"  MOVE "<<event->getButtonMask()<<" x="<<event->getX()<<" y="<<event->getY()<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::SCROLL):
                osg::notify(osg::NOTICE)<<"  SCROLL "<<event->getScrollingMotion()<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::KEYDOWN):
                osg::notify(osg::NOTICE)<<"  KEYDOWN '"<<(char)event->getKey()<<"'"<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::KEYUP):
                osg::notify(osg::NOTICE)<<"  KEYUP '"<<(char)event->getKey()<<"'"<<std::endl;
                break;
            case(osgGA::GUIEventAdapter::RESIZE):
                osg::notify(osg::NOTICE)<<"  RESIZE "<<event->getWindowX()<<"/"<<event->getWindowY()<<" x "<<event->getWindowWidth()<<"/"<<event->getWindowHeight() << std::endl;
                break;
            case(osgGA::GUIEventAdapter::QUIT_APPLICATION):
                osg::notify(osg::NOTICE)<<"  QUIT_APPLICATION " << std::endl;
                break;
            case(osgGA::GUIEventAdapter::FRAME):
                // osg::notify(osg::NOTICE)<<"  FRAME "<<std::endl;
                break;
            default:
                // osg::notify(osg::NOTICE)<<"  Event not handled"<<std::endl;
                break;
        }
    }
#endif

    // osg::notify(osg::NOTICE)<<"Events "<<events.size()<<std::endl;
    
    if ((_keyEventSetsDone!=0) || _quitEventSetsDone)
    {
        for(osgGA::EventQueue::Events::iterator itr = events.begin();
            itr != events.end();
            ++itr)
        {
            osgGA::GUIEventAdapter* event = itr->get();
            switch(event->getEventType())
            {
                case(osgGA::GUIEventAdapter::KEYUP):
                    if (_keyEventSetsDone && event->getKey()==_keyEventSetsDone) _done = true;
                    break;
                
                case(osgGA::GUIEventAdapter::QUIT_APPLICATION):
                    if (_quitEventSetsDone) _done = true;
                    break;
                    
                default:
                    break;
            }
        }
    }
        
    if (_done) return;

    for(osgGA::EventQueue::Events::iterator itr = events.begin();
        itr != events.end();
        ++itr)
    {
        osgGA::GUIEventAdapter* event = itr->get();

        if (_cameraManipulator.valid())
        {
            if (_cameraManipulator->handle( *event, *this)) event->setHandled(true);
        }
        
        for(EventHandlers::iterator hitr = _eventHandlers.begin();
            hitr != _eventHandlers.end();
            ++hitr)
        {
            if ((*hitr)->handle( *event, *this, 0, 0)) event->setHandled(true);
        }
    }

    if (_eventVisitor.valid() && _scene.valid())
    {
        _eventVisitor->setFrameStamp(getFrameStamp());
        _eventVisitor->setTraversalNumber(getFrameStamp()->getFrameNumber());

        for(osgGA::EventQueue::Events::iterator itr = events.begin();
            itr != events.end();
            ++itr)
        {
            osgGA::GUIEventAdapter* event = itr->get();

            _eventVisitor->reset();
            _eventVisitor->addEvent( event );

            getSceneData()->accept(*_eventVisitor);
        }
    }

    
    if (getStats())
    {
        double endEventTraversal = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());

        // update current frames stats
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Event traversal begin time", beginEventTraversal);
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Event traversal end time", endEventTraversal);
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Event traversal time taken", endEventTraversal-beginEventTraversal);
    }


}

void Viewer::updateTraversal()
{
    if (_done) return;

    double beginUpdateTraversal = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());

    if (_scene.valid()) _scene->frameUpdateTraversal();

    if (_cameraManipulator.valid())
    {
        _camera->setViewMatrix(_cameraManipulator->getInverseMatrix());
    }

    updateSlaves();

    if (getStats())
    {
        double endUpdateTraversal = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());

        // update current frames stats
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Update traversal begin time", beginUpdateTraversal);
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Update traversal end time", endUpdateTraversal);
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Update traversal time taken", endUpdateTraversal-beginUpdateTraversal);
    }
}

void Viewer::renderingTraversals()
{
    // check to see if windows are still valid
    checkWindowStatus();

    if (_done) return;

    double beginRenderingTraversals = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());

    osgDB::DatabasePager* dp = _scene.valid() ? _scene->getDatabasePager() : 0;
    if (dp)
    {
        dp->signalBeginFrame(getFrameStamp());
    }

    // osg::notify(osg::NOTICE)<<std::endl<<"Joing _startRenderingBarrier block"<<std::endl;
    

    Contexts contexts;
    getContexts(contexts);
    
    Contexts::iterator itr;
    if (_endDynamicDrawBlock.valid())
    {
        unsigned int numToBlock = 0;
        for(itr = contexts.begin();
            itr != contexts.end();
            ++itr)
        {
            if (((*itr)->getGraphicsThread())) ++numToBlock;
        }

        _endDynamicDrawBlock->set(numToBlock);
    }

    // dispatch the the rendering threads
    if (_startRenderingBarrier.valid()) _startRenderingBarrier->block();

    for(itr = contexts.begin();
        itr != contexts.end();
        ++itr)
    {
        if (_done) return;
        if (!((*itr)->getGraphicsThread()))
        { 
            (*itr)->makeCurrent();
            (*itr)->runOperations();
            (*itr)->releaseContext();
        }
    }

    // osg::notify(osg::NOTICE)<<"Joing _endRenderingDispatchBarrier block"<<std::endl;

    // wait till the dynamic draw is complete.
    if (_endDynamicDrawBlock.valid()) 
    {
        // osg::Timer_t startTick = osg::Timer::instance()->tick();
        _endDynamicDrawBlock->block();
        // osg::notify(osg::NOTICE)<<"Time waiting "<<osg::Timer::instance()->delta_m(startTick, osg::Timer::instance()->tick())<<std::endl;;
    }

    // wait till the rendering dispatch is done.
    if (_endRenderingDispatchBarrier.valid()) _endRenderingDispatchBarrier->block();

    for(itr = contexts.begin();
        itr != contexts.end();
        ++itr)
    {
        if (_done) return;

        if (!((*itr)->getGraphicsThread()))
        { 
            (*itr)->makeCurrent();
            (*itr)->swapBuffers();
            (*itr)->releaseContext();
        }
    }

    if (dp)
    {
        dp->signalEndFrame();
    }

    if (getStats())
    {
        double endRenderingTraversals = osg::Timer::instance()->delta_s(_startTick, osg::Timer::instance()->tick());

        // update current frames stats
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Rendering traversals begin time ", beginRenderingTraversals);
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Rendering traversals end time ", endRenderingTraversals);
        getStats()->setAttribute(_frameStamp->getFrameNumber(), "Rendering traversals time taken", endRenderingTraversals-beginRenderingTraversals);
    }
}