class PickEvent : public osgGA::GUIEventHandler

{

public:

 PickEvent(osg::Geometry* drawable) : _drawable(drawable){}

 ~PickEvent(){}

public:

 bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)

 {

  if (ea.getEventType() == osgGA::GUIEventAdapter::PUSH)

  {

     osgViewer::Viewer* viewer = dynamic_cast<osgViewer::Viewer*>(&aa);

      double x = ea.getX();

      double y = ea.getY();

   osg::Matrix mat = viewer->getCamera()->getViewMatrix() * viewer->getCamera()->getProjectionMatrix();

   mat = mat  * viewer->getCamera()->getViewport()->computeWindowMatrix();

   osg::Matrix inversemat = osg::Matrix::inverse(mat);

   osg::Vec3d v3start = osg::Vec3d(ea.getX(), ea.getY(), 0.0) * inversemat;

   osg::Vec3d v3end = osg::Vec3d(ea.getX(), ea.getY(), 1.0) * inversemat;

   

   osg::TriangleFunctor<MyTestPicker::TriangleIntersector> intersector;

   intersector.set(v3start, v3end);

            _drawable->accept(intersector);

   MyTestPicker::TriangleIntersections::iterator it = intersector._intersections.begin();

   std::pair<const float,MyTestPicker::TriangleIntersection> ps = *it;

   osg::Vec3d v1 =  *(ps.second._v1);

   osg::Vec3d v2 = *(ps.second._v2);

   osg::Vec3d v3 = *(ps.second._v3);

  

   osg::Sphere* sphere = new osg::Sphere;

   sphere->setCenter(v1);

   sphere->setRadius(1);

  

   osg::ShapeDrawable* shapeDrawable = new osg::ShapeDrawable(sphere);

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

   geode->addDrawable(shapeDrawable);

   osg::Camera* camera = viewer->getCamera();

   camera->addChild(geode);

  }

  return false;

  

 }

public:

 osg::Transform* _transform;

 osg::Geometry* _drawable;

};

 

 

void main()

{

     osgViewer::Viewer viewer;

    osg::Node* node = osgDB::readNodeFile("D://cow.osg");

    osg::Group* group = dynamic_cast<osg::Group*>(node);

    osg::Node* child = group->getChild(0);

    osg::Geode* geode = dynamic_cast<osg::Geode*>(child);

    osg::Geometry* drawable = (osg::Geometry*)geode->getDrawable(0);

    viewer.addEventHandler(new PickEvent(drawable));

    viewer.setSceneData(group);

   

    return viewer.run();

}

 

}