使用osg::TriangleFunction仿函数求交

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();
}

}