osg::ref_ptr<osgGA::KeySwitchMatrixManipulator> _manipulator;
_manipulator = new osgGA::KeySwitchMatrixManipulator;
_manipulator->addMatrixManipulator( '1', "Trackball", new osgGA::TrackballManipulator() );
_manipulator->addMatrixManipulator( '2', "Flight", new osgGA::FlightManipulator() );
_manipulator->addMatrixManipulator( '3', "Drive", new osgGA::DriveManipulator() );
_manipulator->addMatrixManipulator( '4', "Terrain", new osgGA::TerrainManipulator() );
_manipulator->addMatrixManipulator( '5', "Orbit", new osgGA::OrbitManipulator() );
_manipulator->addMatrixManipulator( '6', "FirstPerson", new osgGA::FirstPersonManipulator() );
_manipulator->addMatrixManipulator( '7', "Spherical", new osgGA::SphericalManipulator() );
// _viewer->setCameraManipulator( _manipulator.get() );
_viewer->setCameraManipulator( new osgGA::TrackballManipulator() );