/* OpenSceneGraph example, osgtext.
*
*  Permission is hereby granted, free of charge, to any person obtaining a copy
*  of this software and associated documentation files (the "Software"), to deal
*  in the Software without restriction, including without limitation the rights
*  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
*  copies of the Software, and to permit persons to whom the Software is
*  furnished to do so, subject to the following conditions:
*
*  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
*  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
*  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
*  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
*  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
*  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
*  THE SOFTWARE.
*/

#include <osgUtil/Optimizer>

#include <osgDB/ReadFile>
#include <osgDB/WriteFile>
#include <osgDB/Registry>

#include <osgGA/StateSetManipulator>
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>

#include <osg/Geode>
#include <osg/Camera>
#include <osg/ShapeDrawable>
#include <osg/Sequence>
#include <osg/PolygonMode>
#include <osg/io_utils>

#include <osgText/Font>
#include <osgText/Text>

osg::Group* createHUDText()
{

    osg::Group* rootNode = new osg::Group;

    osg::ref_ptr<osgText::Font> font = osgText::readRefFontFile("fonts/arial.ttf");

    //osg::setNotifyLevel(osg::INFO);

    osg::Geode* geode  = new osg::Geode;
    rootNode->addChild(geode);

    float windowHeight = 1024.0f;
    float windowWidth = 1280.0f;
    float margin = 50.0f;

////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Examples of how to set up different text layout
//

    osg::Vec4 layoutColor(1.0f,1.0f,0.0f,1.0f);
    float layoutCharacterSize = 20.0f;

    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(layoutColor);
        text->setCharacterSize(layoutCharacterSize);
        text->setPosition(osg::Vec3(margin,windowHeight-margin,0.0f));

        // the default layout is left to right, typically used in languages
        // originating from europe such as English, French, German, Spanish etc..
        text->setLayout(osgText::Text::LEFT_TO_RIGHT);

        text->setText("text->setLayout(osgText::Text::LEFT_TO_RIGHT);");
        geode->addDrawable(text);
    }

    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(layoutColor);
        text->setCharacterSize(layoutCharacterSize);
        text->setPosition(osg::Vec3(windowWidth-margin,windowHeight-margin,0.0f));

        // right to left layouts would be used for hebrew or arabic fonts.
        text->setLayout(osgText::Text::RIGHT_TO_LEFT);
        text->setAlignment(osgText::Text::RIGHT_BASE_LINE);

        text->setText("text->setLayout(osgText::Text::RIGHT_TO_LEFT);");
        geode->addDrawable(text);
    }

    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(layoutColor);
        text->setPosition(osg::Vec3(margin,windowHeight-margin,0.0f));
        text->setCharacterSize(layoutCharacterSize);

        // vertical font layout would be used for asian fonts.
        text->setLayout(osgText::Text::VERTICAL);

        text->setText("text->setLayout(osgText::Text::VERTICAL);");
        geode->addDrawable(text);
    }


////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Examples of how to set up different font resolution
//

    osg::Vec4 fontSizeColor(0.0f,1.0f,1.0f,1.0f);
    float fontSizeCharacterSize = 30;

    osg::Vec3 cursor = osg::Vec3(margin*2,windowHeight-margin*2,0.0f);

    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(fontSizeColor);
        text->setCharacterSize(fontSizeCharacterSize);
        text->setPosition(cursor);

        // use text that uses 10 by 10 texels as a target resolution for fonts.
        text->setFontResolution(10,10); // blocky but small texture memory usage

        text->setText("text->setFontResolution(10,10); // blocky but small texture memory usage");
        geode->addDrawable(text);
    }

    cursor.y() -= fontSizeCharacterSize;
    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(fontSizeColor);
        text->setCharacterSize(fontSizeCharacterSize);
        text->setPosition(cursor);

        // use text that uses 20 by 20 texels as a target resolution for fonts.
        text->setFontResolution(20,20); // smoother but higher texture memory usage (but still quite low).

        text->setText("text->setFontResolution(20,20); // smoother but higher texture memory usage (but still quite low).");
        geode->addDrawable(text);
    }

    cursor.y() -= fontSizeCharacterSize;
    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(fontSizeColor);
        text->setCharacterSize(fontSizeCharacterSize);
        text->setPosition(cursor);

        // use text that uses 40 by 40 texels as a target resolution for fonts.
        text->setFontResolution(40,40); // even smoother but again higher texture memory usage.

        text->setText("text->setFontResolution(40,40); // even smoother but again higher texture memory usage.");
        geode->addDrawable(text);
    }


////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Examples of how to set up different sized text
//

    osg::Vec4 characterSizeColor(1.0f,0.0f,1.0f,1.0f);

    cursor.y() -= fontSizeCharacterSize*2.0f;

    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(characterSizeColor);
        text->setFontResolution(20,20);
        text->setPosition(cursor);

        // use text that is 20 units high.
        text->setCharacterSize(20); // small

        text->setText("text->setCharacterSize(20.0f); // small");
        geode->addDrawable(text);
    }

    cursor.y() -= 30.0f;
    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(characterSizeColor);
        text->setFontResolution(30,30);
        text->setPosition(cursor);

        // use text that is 30 units high.
        text->setCharacterSize(30.0f); // medium

        text->setText("text->setCharacterSize(30.0f); // medium");
        geode->addDrawable(text);
    }

    cursor.y() -= 50.0f;
    {
        osgText::Text* text = new osgText::Text;
        text->setFont(font);
        text->setColor(characterSizeColor);
        text->setFontResolution(40,40);
        text->setPosition(cursor);

        // use text that is 60 units high.
        text->setCharacterSize(60.0f); // large

        text->setText("text->setCharacterSize(60.0f); // large");
        geode->addDrawable(text);
    }


////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Examples of how to set up different alignments
//

    osg::Vec4 alignmentSizeColor(0.0f,1.0f,0.0f,1.0f);
    float alignmentCharacterSize = 25.0f;
    cursor.x() = 640;
    cursor.y() = margin*4.0f;

    typedef std::pair<osgText::Text::AlignmentType,std::string> AlignmentPair;
    typedef std::vector<AlignmentPair> AlignmentList;
    AlignmentList alignmentList;
    alignmentList.push_back(AlignmentPair(osgText::Text::LEFT_TOP,"text->setAlignment(\nosgText::Text::LEFT_TOP);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::LEFT_CENTER,"text->setAlignment(\nosgText::Text::LEFT_CENTER);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::LEFT_BOTTOM,"text->setAlignment(\nosgText::Text::LEFT_BOTTOM);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::CENTER_TOP,"text->setAlignment(\nosgText::Text::CENTER_TOP);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::CENTER_CENTER,"text->setAlignment(\nosgText::Text::CENTER_CENTER);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::CENTER_BOTTOM,"text->setAlignment(\nosgText::Text::CENTER_BOTTOM);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::RIGHT_TOP,"text->setAlignment(\nosgText::Text::RIGHT_TOP);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::RIGHT_CENTER,"text->setAlignment(\nosgText::Text::RIGHT_CENTER);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::RIGHT_BOTTOM,"text->setAlignment(\nosgText::Text::RIGHT_BOTTOM);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::LEFT_BASE_LINE,"text->setAlignment(\nosgText::Text::LEFT_BASE_LINE);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::CENTER_BASE_LINE,"text->setAlignment(\nosgText::Text::CENTER_BASE_LINE);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::RIGHT_BASE_LINE,"text->setAlignment(\nosgText::Text::RIGHT_BASE_LINE);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::LEFT_BOTTOM_BASE_LINE,"text->setAlignment(\nosgText::Text::LEFT_BOTTOM_BASE_LINE);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::CENTER_BOTTOM_BASE_LINE,"text->setAlignment(\nosgText::Text::CENTER_BOTTOM_BASE_LINE);"));
    alignmentList.push_back(AlignmentPair(osgText::Text::RIGHT_BOTTOM_BASE_LINE,"text->setAlignment(\nosgText::Text::RIGHT_BOTTOM_BASE_LINE);"));


    osg::Sequence* sequence = new osg::Sequence;
    {
        for(AlignmentList::iterator itr=alignmentList.begin();
            itr!=alignmentList.end();
            ++itr)
        {
            osg::Geode* alignmentGeode = new osg::Geode;
            sequence->addChild(alignmentGeode);
            sequence->setTime(sequence->getNumChildren(), 1.0f);

            osgText::Text* text = new osgText::Text;
            text->setFont(font);
            text->setColor(alignmentSizeColor);
            text->setCharacterSize(alignmentCharacterSize);
            text->setPosition(cursor);
            text->setDrawMode(osgText::Text::TEXT|osgText::Text::ALIGNMENT|osgText::Text::BOUNDINGBOX);

            text->setAlignment(itr->first);
            text->setText(itr->second);

            alignmentGeode->addDrawable(text);


        }

    }

    sequence->setMode(osg::Sequence::START);
    sequence->setInterval(osg::Sequence::LOOP, 0, -1);
    sequence->setDuration(1.0f, -1);

    rootNode->addChild(sequence);


////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Examples of how to set up different fonts...
//

    cursor.x() = margin*2.0f;
    cursor.y() = margin*2.0f;

    osg::Vec4 fontColor(1.0f,0.5f,0.0f,1.0f);
    float fontCharacterSize = 20.0f;
    float spacing = 40.0f;

    {
        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setColor(fontColor);
        text->setPosition(cursor);
        text->setCharacterSize(fontCharacterSize);

        text->setFont(0);
        text->setText("text->setFont(0); // inbuilt font.");
        geode->addDrawable(text);

        cursor.x() = text->getBoundingBox().xMax() + spacing ;
    }

    {
        osg::ref_ptr<osgText::Font> arial = osgText::readRefFontFile("fonts/arial.ttf");

        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setColor(fontColor);
        text->setPosition(cursor);
        text->setCharacterSize(fontCharacterSize);

        text->setFont(arial);
        text->setText(arial!=0?
                      "text->setFont(\"fonts/arial.ttf\");":
                      "unable to load \"fonts/arial.ttf\"");
        geode->addDrawable(text);

        cursor.x() = text->getBoundingBox().xMax() + spacing ;
    }

    {
        osg::ref_ptr<osgText::Font> times = osgText::readRefFontFile("fonts/times.ttf");

        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setColor(fontColor);
        text->setPosition(cursor);
        text->setCharacterSize(fontCharacterSize);

        geode->addDrawable(text);
        text->setFont(times);
        text->setText(times!=0?
                      "text->setFont(\"fonts/times.ttf\");":
                      "unable to load \"fonts/times.ttf\"");

        cursor.x() = text->getBoundingBox().xMax() + spacing ;
    }

    cursor.x() = margin*2.0f;
    cursor.y() = margin;

    {
        osg::ref_ptr<osgText::Font> dirtydoz = osgText::readRefFontFile("fonts/dirtydoz.ttf");

        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setColor(fontColor);
        text->setPosition(cursor);
        text->setCharacterSize(fontCharacterSize);

        text->setFont(dirtydoz);
        text->setText(dirtydoz!=0?
                      "text->setFont(\"fonts/dirtydoz.ttf\");":
                      "unable to load \"fonts/dirtydoz.ttf\"");
        geode->addDrawable(text);

        cursor.x() = text->getBoundingBox().xMax() + spacing ;
    }

    {
        osg::ref_ptr<osgText::Font> fudd = osgText::readRefFontFile("fonts/fudd.ttf");

        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setColor(fontColor);
        text->setPosition(cursor);
        text->setCharacterSize(fontCharacterSize);

        text->setFont(fudd);
        text->setText(fudd!=0?
                      "text->setFont(\"fonts/fudd.ttf\");":
                      "unable to load \"fonts/fudd.ttf\"");
        geode->addDrawable(text);

        cursor.x() = text->getBoundingBox().xMax() + spacing ;
    }

    return rootNode;
}




// create text which sits in 3D space such as would be inserted into a normal model
osg::Group* create3DText(const osg::Vec3& center,float radius)
{

    osg::Geode* geode  = new osg::Geode;

////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Examples of how to set up axis/orientation alignments
//

    float characterSize=radius*0.2f;


    osg::Vec3 pos(center.x()-radius*.5f,center.y()-radius*.5f,center.z()-radius*.5f);

    osgText::Text* text1 = new osgText::Text;
    text1->setFont("fonts/times.ttf");
    text1->setCharacterSize(characterSize);
    text1->setPosition(pos);
    text1->setAxisAlignment(osgText::Text::XY_PLANE);
    text1->setText("XY_PLANE");
    geode->addDrawable(text1);

    osgText::Text* text2 = new osgText::Text;
    text2->setFont("fonts/times.ttf");
    text2->setCharacterSize(characterSize);
    text2->setPosition(pos);
    text2->setAxisAlignment(osgText::Text::YZ_PLANE);
    text2->setText("YZ_PLANE");
    geode->addDrawable(text2);

    osgText::Text* text3 = new osgText::Text;
    text3->setFont("fonts/times.ttf");
    text3->setCharacterSize(characterSize);
    text3->setPosition(pos);
    text3->setAxisAlignment(osgText::Text::XZ_PLANE);
    text3->setText("XZ_PLANE");
    geode->addDrawable(text3);

    osg::Vec4 characterSizeModeColor(1.0f,0.0f,0.5f,1.0f);

    osgText::Text* text4 = new osgText::Text;
    text4->setFont("fonts/times.ttf");
    text4->setCharacterSize(characterSize);
    text4->setPosition(center);
    text4->setAxisAlignment(osgText::Text::SCREEN);

    // reproduce outline bounding box compute problem with backdrop on.
    text4->setBackdropType(osgText::Text::OUTLINE);
    text4->setDrawMode(osgText::Text::TEXT | osgText::Text::BOUNDINGBOX);

    text4->setText("SCREEN");
    geode->addDrawable(text4);

    osgText::Text* text5 = new osgText::Text;
    text5->setColor(characterSizeModeColor);
    text5->setFont("fonts/times.ttf");
    //text5->setCharacterSize(characterSize);
    text5->setCharacterSize(32.0f); // medium
    text5->setPosition(center - osg::Vec3(0.0, 0.0, 0.2));
    text5->setAxisAlignment(osgText::Text::SCREEN);
    text5->setCharacterSizeMode(osgText::Text::SCREEN_COORDS);
    text5->setDrawMode(osgText::Text::TEXT | osgText::Text::BOUNDINGBOX);
    text5->setText("CharacterSizeMode SCREEN_COORDS(size 32.0)");
    geode->addDrawable(text5);

    osgText::Text* text6 = new osgText::Text;
    text6->setColor(characterSizeModeColor);
    text6->setFont("fonts/times.ttf");
    text6->setCharacterSize(characterSize);
    text6->setPosition(center - osg::Vec3(0.0, 0.0, 0.4));
    text6->setAxisAlignment(osgText::Text::SCREEN);
    text6->setCharacterSizeMode(osgText::Text::OBJECT_COORDS_WITH_MAXIMUM_SCREEN_SIZE_CAPPED_BY_FONT_HEIGHT);
    text6->setText("CharacterSizeMode OBJECT_COORDS_WITH_MAXIMUM_SCREEN_SIZE_CAPPED_BY_FONT_HEIGHT");
    geode->addDrawable(text6);

    osgText::Text* text7 = new osgText::Text;
    text7->setColor(characterSizeModeColor);
    text7->setFont("fonts/times.ttf");
    text7->setCharacterSize(characterSize);
    text7->setPosition(center - osg::Vec3(0.0, 0.0, 0.6));
    text7->setAxisAlignment(osgText::Text::SCREEN);
    text7->setCharacterSizeMode(osgText::Text::OBJECT_COORDS);
    text7->setText("CharacterSizeMode OBJECT_COORDS (default)");
    geode->addDrawable(text7);


#if 0
    osg::ShapeDrawable* shape = new osg::ShapeDrawable(new osg::Sphere(center,characterSize*0.2f));
    shape->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::ON);
    geode->addDrawable(shape);
#endif

    osg::Group* rootNode = new osg::Group;
    rootNode->addChild(geode);

    return rootNode;
}

class UpdateTextOperation : public osg::Operation
{
public:

    UpdateTextOperation(const osg::Vec3& center, float diameter, osg::Group* group):
        osg::Referenced(true),
        Operation("UpdateTextOperation", true),
        _center(center),
        _diameter(diameter),
        _maxNumChildren(200),
        _maxNumTextPerGeode(10),
        _group(group)
    {
    }

    virtual void operator () (osg::Object* callingObject)
    {
        // decided which method to call according to whole has called me.
        osgViewer::Viewer* viewer = dynamic_cast<osgViewer::Viewer*>(callingObject);

        if (viewer) update();
        else load();
    }

    void update()
    {
        // osg::notify(osg::NOTICE)<<"*** Doing update"<<std::endl;

        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);

        if (_mergeSubgraph.valid())
        {
            _group->addChild(_mergeSubgraph.get());

            _mergeSubgraph = 0;

            if (_group->getNumChildren()>_maxNumChildren)
            {
                osg::Geode* geode = dynamic_cast<osg::Geode*>(_group->getChild(0));
                if (geode)
                {
                    _availableSubgraph.push_back(geode);
                    geode->removeDrawables(0,geode->getNumDrawables());
                }
                _group->removeChild(0,1);
            }

            _waitOnMergeBlock.release();
        }
    }

    void load()
    {

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

        osg::ref_ptr<osg::Geode> geode;
        {
            OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
            if (!_availableSubgraph.empty())
            {
                geode = _availableSubgraph.front();
                _availableSubgraph.pop_front();
            }
        }

        if (!geode) geode = new osg::Geode;

        for(unsigned int i=0; i<_maxNumTextPerGeode; ++i)
        {
            float x = float(rand()) / float(RAND_MAX) - 0.5f;
            float y = float(rand()) / float(RAND_MAX) - 0.5f;
            float z = float(i)      / float(_maxNumTextPerGeode) - 0.5f;
            osg::Vec3 position(x, y, z);

            std::string str;
            unsigned int _numCharacters = 5;
            for(unsigned int ni=0; ni<_numCharacters;++ni)
            {
                str.push_back(char(32.0 + (float(rand())/float(RAND_MAX))*128.0f));
            }

            osgText::Text* text = new osgText::Text;
            text->setDataVariance(osg::Object::DYNAMIC);
            text->setPosition(_center + position * _diameter);
            text->setFont("times.ttf");
            text->setText(str);
            text->setCharacterSize(0.025f * _diameter);
            text->setAxisAlignment(osgText::Text::SCREEN);

            geode->addDrawable(text);
        }


        {
            OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
            _mergeSubgraph = geode;
        }

        // osg::notify(osg::NOTICE)<<"Waiting on merge"<<std::endl;

        _waitOnMergeBlock.block();

    }

    virtual void release()
    {
        _waitOnMergeBlock.release();
    }

    typedef std::list< osg::ref_ptr<osg::Geode> > AvailableList;

    osg::Vec3                   _center;
    float                       _diameter;
    unsigned int                _maxNumChildren;
    unsigned int                _maxNumTextPerGeode;

    OpenThreads::Mutex          _mutex;
    osg::ref_ptr<osg::Group>    _group;
    osg::ref_ptr<osg::Geode>    _mergeSubgraph;
    AvailableList               _availableSubgraph;
    OpenThreads::Block          _waitOnMergeBlock;

    unsigned int                _counter;

};


struct TextCounterCallback : public osg::NodeCallback
{
    unsigned int _textCounter;

    TextCounterCallback():
        _textCounter(100000) {}

    virtual void operator()(osg::Node* node, osg::NodeVisitor*)
    {
        osgText::Text* text = dynamic_cast<osgText::Text*>(node);
        if (text)
        {
            std::stringstream str;
            str <<"Text Counter "<<_textCounter<<std::endl;
            OSG_NOTICE<<"Udating text"<<str.str()<<std::endl;

            text->setText(str.str());

            ++_textCounter;
        }
    }
};


int main(int argc, char** argv)
{
    osg::ArgumentParser arguments(&argc, argv);

    // construct the viewer.
    osgViewer::Viewer viewer(arguments);

    typedef std::list< osg::ref_ptr<osg::OperationThread> > Threads;

    Threads operationThreads;
    osg::ref_ptr<UpdateTextOperation> updateOperation;
    unsigned int numThreads = 0;

    if (arguments.read("--simple"))
    {
        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setFont("fonts/times.ttf");
        text->setAxisAlignment(osgText::Text::XZ_PLANE);
        text->setDrawMode(osgText::Text::TEXT|osgText::Text::ALIGNMENT|osgText::Text::BOUNDINGBOX|osgText::Text::FILLEDBOUNDINGBOX);
        text->setText("This is a simple test");

        viewer.setSceneData(text.get());
    }
    else if (arguments.read("--plain"))
    {
        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setFont("fonts/times.ttf");
        text->setAxisAlignment(osgText::Text::XZ_PLANE);
        text->setText("This is a plain test");

        viewer.setSceneData(text.get());
    }
    else if (arguments.read("--counter"))
    {
        osg::ref_ptr<osgText::Text> text = new osgText::Text;
        text->setUpdateCallback(new TextCounterCallback());
        text->setFont("fonts/times.ttf");
        text->setAxisAlignment(osgText::Text::XZ_PLANE);
        text->setText("This is a counter test");

        viewer.setSceneData(text.get());
    }
    else if (arguments.read("--mt", numThreads) || arguments.read("--mt"))
    {
        // construct a multi-threaded text updating test.
        if (numThreads==0) numThreads = 1;

        // create a group to add everything into.
        osg::Group* mainGroup = new osg::Group;

        osg::Vec3 center(0.5f,0.5f,0.5f);
        float diameter = 1.0f;

        osg::ref_ptr<osg::Node> loadedModel = osgDB::readRefNodeFiles(arguments);
        if (loadedModel.valid())
        {
            mainGroup->addChild(loadedModel);

            center = loadedModel->getBound().center();
            diameter = loadedModel->getBound().radius() * 2.0f;
        }

        for(unsigned int i=0; i<numThreads; ++i)
        {
            osg::Group* textGroup = new osg::Group;
            mainGroup->addChild(textGroup);

            // create the background thread
            osg::OperationThread* operationThread = new osg::OperationThread;

            operationThreads.push_back(operationThread);

            // create the operation that will run in the background and
            // sync once per frame with the main viewer loop.
            updateOperation = new UpdateTextOperation(center, diameter, textGroup);

            // add the operation to the operation thread and start it.
            operationThread->add(updateOperation.get());
            operationThread->startThread();

            // add the operation to the viewer to sync once per frame.
            viewer.addUpdateOperation(updateOperation.get());


            // add a unit cube for the text to appear within.
            osg::Geode* geode = new osg::Geode;
            geode->getOrCreateStateSet()->setAttribute(new osg::PolygonMode(osg::PolygonMode::FRONT_AND_BACK,osg::PolygonMode::LINE));
            geode->addDrawable(new osg::ShapeDrawable(new osg::Box(center,diameter)));

            mainGroup->addChild(geode);
        }

        viewer.setSceneData(mainGroup);
    }
    else
    {
        // prepare scene.
        osg::Vec3 center(0.0f,0.0f,0.0f);
        float radius = 1.0f;

        // make sure the root node is group so we can add extra nodes to it.
        osg::Group* group = new osg::Group;

        if (true)
        {
            // create the hud.
            osg::Camera* camera = new osg::Camera;
            camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
            camera->setProjectionMatrixAsOrtho2D(0,1280,0,1024);
            camera->setViewMatrix(osg::Matrix::identity());
            camera->setClearMask(GL_DEPTH_BUFFER_BIT);
            camera->addChild(createHUDText());
            camera->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::OFF);

            group->addChild(camera);
        }

        if (true)
        {
            group->addChild(create3DText(center,radius));
        }

        // set the scene to render
        viewer.setSceneData(group);
    }

    std::string filename;
    if (arguments.read("-o",filename))
    {
        osgDB::writeNodeFile(*viewer.getSceneData(),filename);
        return 0;
    }

    viewer.addEventHandler( new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()) );
    viewer.addEventHandler(new osgViewer::StatsHandler());

    viewer.run();

    if (!operationThreads.empty())
    {
        for(Threads::iterator itr = operationThreads.begin();
            itr != operationThreads.end();
            ++itr)
        {
            (*itr)->cancel();
        }
    }

    return 0;
}