/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This application is open source and may be redistributed and/or modified   
 * freely and without restriction, both in commericial and non commericial applications,
 * as long as this copyright notice is maintained.
 * 
 * This application 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.
*/

#include <osgDB/ReadFile>
#include <osgUtil/Optimizer>
#include <osg/CoordinateSystemNode>

#include <osg/Switch>
#include <osgText/Text>

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

#include <osgGA/TrackballManipulator>
#include <osgGA/FlightManipulator>
#include <osgGA/DriveManipulator>
#include <osgGA/KeySwitchMatrixManipulator>
#include <osgGA/StateSetManipulator>
#include <osgGA/AnimationPathManipulator>
#include <osgGA/TerrainManipulator>
#include <osg/Material>
#include <osg/BlendFunc> 
#include <osg/CullFace> 
#include <iostream>


float currentAlpha, addinc=-0.001;
osg::ref_ptr<osg::Node> loadedModel;



void  setAlpha2()
{
	if (loadedModel.valid())
	{
        currentAlpha += addinc;
        if (currentAlpha >= 1.0)
        {
               addinc=-0.001; currentAlpha = 1;
        }
        if (currentAlpha <= 0.0)
        {
               addinc=0.001; currentAlpha = 0;
        }

		osg::StateSet *ss = loadedModel ->getOrCreateStateSet();
 		osg::Material* blendMaterial = (osg::Material*)(ss->getAttribute(osg::StateAttribute::MATERIAL));

		if(blendMaterial ==0)
        {
			blendMaterial = new osg::Material();
        }

		 
  	    blendMaterial->setAlpha( osg::Material::FRONT, currentAlpha);
		osg::BlendFunc *bl = new osg::BlendFunc();
        bl->setFunction(osg::BlendFunc::SRC_ALPHA, osg::BlendFunc::ONE_MINUS_SRC_ALPHA); 
		ss->setAttributeAndModes(bl, osg::StateAttribute::ON |osg::StateAttribute::OVERRIDE);
		ss->setAttributeAndModes(blendMaterial ,osg::StateAttribute::ON |osg::StateAttribute::OVERRIDE);
		ss->setRenderingHint(osg::StateSet::TRANSPARENT_BIN);
        osg::CullFace *cl = new osg::CullFace();
        ss->setAttributeAndModes(cl, osg::StateAttribute::ON |osg::StateAttribute::OVERRIDE);

	}
}


int main(int argc, char** argv)
{
    // use an ArgumentParser object to manage the program arguments.
    osg::ArgumentParser arguments(&argc,argv);

    arguments.getApplicationUsage()->setApplicationName(arguments.getApplicationName());
    arguments.getApplicationUsage()->setDescription(arguments.getApplicationName()+" is the standard OpenSceneGraph example which loads and visualises 3d models.");
    arguments.getApplicationUsage()->setCommandLineUsage(arguments.getApplicationName()+" [options] filename ...");
    arguments.getApplicationUsage()->addCommandLineOption("--image <filename>","Load an image and render it on a quad");
    arguments.getApplicationUsage()->addCommandLineOption("--dem <filename>","Load an image/DEM and render it on a HeightField");
    arguments.getApplicationUsage()->addCommandLineOption("-h or --help","Display command line parameters");
    arguments.getApplicationUsage()->addCommandLineOption("--help-env","Display environmental variables available");
    arguments.getApplicationUsage()->addCommandLineOption("--help-keys","Display keyboard & mouse bindings available");
    arguments.getApplicationUsage()->addCommandLineOption("--help-all","Display all command line, env vars and keyboard & mouse bindings.");
    arguments.getApplicationUsage()->addCommandLineOption("--SingleThreaded","Select SingleThreaded threading model for viewer.");
    arguments.getApplicationUsage()->addCommandLineOption("--CullDrawThreadPerContext","Select CullDrawThreadPerContext threading model for viewer.");
    arguments.getApplicationUsage()->addCommandLineOption("--DrawThreadPerContext","Select DrawThreadPerContext threading model for viewer.");
    arguments.getApplicationUsage()->addCommandLineOption("--CullThreadPerCameraDrawThreadPerContext","Select CullThreadPerCameraDrawThreadPerContext threading model for viewer.");

    // if user request help write it out to cout.
    bool helpAll = arguments.read("--help-all");
    unsigned int helpType = ((helpAll || arguments.read("-h") || arguments.read("--help"))? osg::ApplicationUsage::COMMAND_LINE_OPTION : 0 ) |
                            ((helpAll ||  arguments.read("--help-env"))? osg::ApplicationUsage::ENVIRONMENTAL_VARIABLE : 0 ) |
                            ((helpAll ||  arguments.read("--help-keys"))? osg::ApplicationUsage::KEYBOARD_MOUSE_BINDING : 0 );
    if (helpType)
    {
        arguments.getApplicationUsage()->write(std::cout, helpType);
        return 1;
    }

    osgViewer::Viewer viewer(arguments);
    
    // report any errors if they have occurred when parsing the program arguments.
    if (arguments.errors())
    {
        arguments.writeErrorMessages(std::cout);
        return 1;
    }
    
    if (arguments.argc()<=1)
    {
        arguments.getApplicationUsage()->write(std::cout,osg::ApplicationUsage::COMMAND_LINE_OPTION);
        return 1;
    }

    // set up the camera manipulators.
    {
        osg::ref_ptr<osgGA::KeySwitchMatrixManipulator> keyswitchManipulator = new osgGA::KeySwitchMatrixManipulator;

        keyswitchManipulator->addMatrixManipulator( '1', "Trackball", new osgGA::TrackballManipulator() );
        keyswitchManipulator->addMatrixManipulator( '2', "Flight", new osgGA::FlightManipulator() );
        keyswitchManipulator->addMatrixManipulator( '3', "Drive", new osgGA::DriveManipulator() );
        keyswitchManipulator->addMatrixManipulator( '4', "Terrain", new osgGA::TerrainManipulator() );

        std::string pathfile;
        char keyForAnimationPath = '5';
        while (arguments.read("-p",pathfile))
        {
            osgGA::AnimationPathManipulator* apm = new osgGA::AnimationPathManipulator(pathfile);
            if (apm || !apm->valid()) 
            {
                unsigned int num = keyswitchManipulator->getNumMatrixManipulators();
                keyswitchManipulator->addMatrixManipulator( keyForAnimationPath, "Path", apm );
                keyswitchManipulator->selectMatrixManipulator(num);
                ++keyForAnimationPath;
            }
        }

        viewer.setCameraManipulator( keyswitchManipulator.get() );
    }

    // add the state manipulator
    viewer.addEventHandler( new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()) );
    
    // add the thread model handler
    viewer.addEventHandler(new osgViewer::ThreadingHandler);

    // add the window size toggle handler
    viewer.addEventHandler(new osgViewer::WindowSizeHandler);
        
    // add the stats handler
    viewer.addEventHandler(new osgViewer::StatsHandler);

    // add the help handler
    viewer.addEventHandler(new osgViewer::HelpHandler(arguments.getApplicationUsage()));

    // add the record camera path handler
    viewer.addEventHandler(new osgViewer::RecordCameraPathHandler);

    // add the LOD Scale handler
    viewer.addEventHandler(new osgViewer::LODScaleHandler);

    // load the data
     loadedModel = osgDB::readNodeFiles(arguments);
    if (!loadedModel) 
    {
        std::cout << arguments.getApplicationName() <<": No data loaded" << std::endl;
        return 1;
    }

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

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


    // optimize the scene graph, remove redundant nodes and state etc.
    osgUtil::Optimizer optimizer;
    optimizer.optimize(loadedModel.get());

    viewer.setSceneData( loadedModel.get() );

    
    viewer.realize();

	currentAlpha = 1.0;

	while(!viewer.done()  )
    {
		setAlpha2();

		viewer.frame();
		
	}
    //return viewer.run();

}