/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 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 <osgUtil/Optimizer>
#include <osgDB/ReadFile>
#include <osgProducer/Viewer>

#include <osg/Material>
#include <osg/Geode>
#include <osg/BlendFunc>
#include <osg/Depth>
#include <osg/Projection>
#include <osg/MatrixTransform>

#include <osgText/Text>


osg::Node* createHUD()
{
    osg::Geode* geode = new osg::Geode();
    
    std::string timesFont("fonts/times.ttf");

    // turn lighting off for the text and disable depth test to ensure its always ontop.
    osg::StateSet* stateset = geode->getOrCreateStateSet();
    stateset->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
    stateset->setMode(GL_DEPTH_TEST,osg::StateAttribute::OFF);

    osg::Vec3 position(150.0f,800.0f,0.0f);
    osg::Vec3 delta(0.0f,-120.0f,0.0f);

    {
        osgText::Text* text = new  osgText::Text;
        geode->addDrawable( text );

        text->setFont(timesFont);
        text->setText("Head Up Displays are simple :-)");
        text->setPosition(position);
        
        position += delta;
    }    


    {
        osgText::Text* text = new  osgText::Text;
        geode->addDrawable( text );

        text->setFont(timesFont);
        text->setText("All you need to do is create your text in a subgraph.");
        text->setPosition(position);
        
        position += delta;
    }    


    {
        osgText::Text* text = new  osgText::Text;
        geode->addDrawable( text );

        text->setFont(timesFont);
        text->setText("Disable depth test in this subgraph to ensure its always ontop.");
        text->setPosition(position);
        
        position += delta;
    }    

    {
        osgText::Text* text = new  osgText::Text;
        geode->addDrawable( text );

        text->setFont(timesFont);
        text->setText("Then place a osg::Projection node above the subgraph\nto create an othrograph projection.");
        text->setPosition(position);
        
        position += delta;
    }    

    {
        osgText::Text* text = new  osgText::Text;
        geode->addDrawable( text );

        text->setFont(timesFont);
        text->setText("And add an osg::ModelViewMatrix set to ABSOLUTE to ensure\nit remains independent from any external model view matrices.");
        text->setPosition(position);
        
        position += delta;
    }    

    // create the hud.
    osg::MatrixTransform* modelview_abs = new osg::MatrixTransform;
    modelview_abs->setReferenceFrame(osg::Transform::RELATIVE_TO_ABSOLUTE);
    modelview_abs->setMatrix(osg::Matrix::identity());
    modelview_abs->addChild(geode);

    osg::Projection* projection = new osg::Projection;
    projection->setMatrix(osg::Matrix::ortho2D(0,1280,0,1024));
    projection->addChild(modelview_abs);

    return projection;

}

int main( int argc, char **argv )
{

    // use an ArgumentParser object to manage the program arguments.
    osg::ArgumentParser arguments(&argc,argv);
    
    // set up the usage document, in case we need to print out how to use this program.
    arguments.getApplicationUsage()->setCommandLineUsage(arguments.getProgramName()+" [options] [filename] ...");
    arguments.getApplicationUsage()->addCommandLineOption("-h or --help","Display this information");
    

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

    // set up the value with sensible default event handlers.
    viewer.setUpViewer(osgProducer::Viewer::STANDARD_SETTINGS);

    // get details on keyboard and mouse bindings used by the viewer.
    viewer.getUsage(*arguments.getApplicationUsage());

    // if user request help write it out to cout.
    if (arguments.read("-h") || arguments.read("--help"))
    {
        arguments.getApplicationUsage()->write(cout);
        return 1;
    }

    // any option left unread are converted into errors to write out later.
    arguments.reportRemainingOptionsAsUnrecognized();

    // report any errors if they have occured when parsing the program aguments.
    if (arguments.errors())
    {
        arguments.writeErrorMessages(cout);
        return 1;
    }


    // read the scene from the list of file specified commandline args.
    osg::ref_ptr<osg::Node> scene = osgDB::readNodeFiles(arguments);

    osg::ref_ptr<osg::Group> group = dynamic_cast<osg::Group*>(scene.get());
    if (!group)
    {
        group = new osg::Group;
        group->addChild(scene.get());
    }

    // add the HUD subgraph.    
    group->addChild(createHUD());

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

    // create the windows and run the threads.
    viewer.realize(Producer::CameraGroup::ThreadPerCamera);

    while( !viewer.done() )
    {
        // wait for all cull and draw threads to complete.
        viewer.sync();

        // update the scene by traversing it with the the update visitor which will
        // call all node update callbacks and animations.
        viewer.update();
         
        // fire off the cull and draw traversals of the scene.
        viewer.frame();
        
    }
    
    return 0;
}