/* OpenSceneGraph example, osgdepthpartion.
*
*  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/UpdateVisitor>

#include <osgDB/ReadFile>

#include <osg/ShapeDrawable>
#include <osg/PositionAttitudeTransform>

#include <osgGA/TrackballManipulator>
#include <osgGA/StateSetManipulator>

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

const double r_earth = 6378.137;
const double r_sun = 695990.0;
const double AU = 149697900.0;

osg::Node* createScene()
{
    // Create the Earth, in blue
    osg::ShapeDrawable *earth_sd = new osg::ShapeDrawable;
    osg::Sphere* earth_sphere = new osg::Sphere;
    earth_sphere->setName("EarthSphere");
    earth_sphere->setRadius(r_earth);
    earth_sd->setShape(earth_sphere);
    earth_sd->setColor(osg::Vec4(0, 0, 1.0, 1.0));

    osg::Geode* earth_geode = new osg::Geode;
    earth_geode->setName("EarthGeode");
    earth_geode->addDrawable(earth_sd);
    
    // Create the Sun, in yellow
    osg::ShapeDrawable *sun_sd = new osg::ShapeDrawable;
    osg::Sphere* sun_sphere = new osg::Sphere;
    sun_sphere->setName("SunSphere");
    sun_sphere->setRadius(r_sun);
    sun_sd->setShape(sun_sphere);
    sun_sd->setColor(osg::Vec4(1.0, 0.0, 0.0, 1.0));

    osg::Geode* sun_geode = new osg::Geode;
    sun_geode->setName("SunGeode");
    sun_geode->addDrawable(sun_sd);

    // Move the sun behind the earth
    osg::PositionAttitudeTransform *pat = new osg::PositionAttitudeTransform;
    pat->setPosition(osg::Vec3d(0.0, AU, 0.0));
    pat->addChild(sun_geode);
    
    osg::Geometry * unitCircle = new osg::Geometry();
    {
      osg::Vec4Array * colours = new osg::Vec4Array(1);
      (*colours)[0] = osg::Vec4d(1.0,1.0,1.0,1.0);
      unitCircle->setColorArray(colours);
      unitCircle->setColorBinding(osg::Geometry::BIND_OVERALL);
      const unsigned int n_points = 1024;
      osg::Vec3Array * coords = new osg::Vec3Array(n_points);
      const double dx = 2.0*osg::PI/n_points;
      double s,c;
      for (unsigned int j=0; j<n_points; ++j) {
    s = sin(dx*j);
    c = cos(dx*j);
    (*coords)[j].set(osg::Vec3d(c,s,0.0));
      }
      unitCircle->setVertexArray(coords);
      unitCircle->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
      unitCircle->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP,0,n_points));
    }

    osg::Geometry *axes = new osg::Geometry;
    {
      osg::Vec4Array *colours = new osg::Vec4Array(1);
      (*colours)[0] = osg::Vec4d(1.0,0.0,0.0,1.0);
      axes->setColorArray(colours);
      axes->setColorBinding(osg::Geometry::BIND_OVERALL);
      osg::Vec3Array *coords = new osg::Vec3Array(6);
      (*coords)[0].set(osg::Vec3d(0.0, 0.0, 0.0));
      (*coords)[1].set(osg::Vec3d(0.5, 0.0, 0.0));
      (*coords)[2].set(osg::Vec3d(0.0, 0.0, 0.0));
      (*coords)[3].set(osg::Vec3d(0.0, 0.5, 0.0));
      (*coords)[4].set(osg::Vec3d(0.0, 0.0, 0.0));
      (*coords)[5].set(osg::Vec3d(0.0, 0.0, 0.5));
      axes->setVertexArray(coords);
      axes->getOrCreateStateSet()->setMode(GL_LIGHTING,osg::StateAttribute::OFF);
      axes->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::LINES,0,6));
    }
    
    // Earth orbit
    osg::Geode * earthOrbitGeode = new osg::Geode;
    earthOrbitGeode->addDrawable(unitCircle);
    earthOrbitGeode->addDrawable(axes);
    earthOrbitGeode->setName("EarthOrbitGeode");
    
    osg::PositionAttitudeTransform * earthOrbitPAT = new osg::PositionAttitudeTransform;
    earthOrbitPAT->setScale(osg::Vec3d(AU,AU,AU));
    earthOrbitPAT->setPosition(osg::Vec3d(0.0, AU, 0.0));
    earthOrbitPAT->addChild(earthOrbitGeode);
    earthOrbitPAT->setName("EarthOrbitPAT");
    
    osg::Group* scene = new osg::Group;
    scene->setName("SceneGroup");
    scene->addChild(earth_geode);
    scene->addChild(pat);
    scene->addChild(earthOrbitPAT);
    
    return scene;
}

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

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

    // construct the viewer.
    osgViewer::Viewer viewer;

    // add the state manipulator
    viewer.addEventHandler( new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()) );

    // add stats
    viewer.addEventHandler( new osgViewer::StatsHandler() );

    bool needToSetHomePosition = false;

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

    // if one hasn't been loaded create an earth and sun test model.
    if (!scene) 
    {
        scene = createScene(); 
        needToSetHomePosition = true;
    }
    // pass the loaded scene graph to the viewer.
    viewer.setSceneData(scene.get());

    viewer.setCameraManipulator(new osgGA::TrackballManipulator);

    if (needToSetHomePosition)
    {
        viewer.getCameraManipulator()->setHomePosition(osg::Vec3d(0.0,-5.0*r_earth,0.0),osg::Vec3d(0.0,0.0,0.0),osg::Vec3d(0.0,0.0,1.0));
    }
    
    double zNear=1.0, zMid=10.0, zFar=1000.0;
    if (arguments.read("--depth-partition",zNear, zMid, zFar))
    {
        // set up depth partitioning
        osg::ref_ptr<osgViewer::DepthPartitionSettings> dps = new osgViewer::DepthPartitionSettings;
        dps->_mode = osgViewer::DepthPartitionSettings::FIXED_RANGE;
        dps->_zNear = zNear;
        dps->_zMid = zMid;
        dps->_zFar = zFar;
        viewer.setUpDepthPartition(dps.get());
    }
    else
    {
        // set up depth partitioning with default settings
        viewer.setUpDepthPartition();
    }
    

    return viewer.run();
}