osg::ref_ptr<osg::Node> loadedModel = osgDB::readNodeFile("cow.osg");

 osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;

 {

  osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;

  traits->x = 40;

  traits->y = 40;

  traits->width = 600;

  traits->height = 480;

  traits->windowDecoration = true;

  traits->doubleBuffer = true;

  traits->sharedContext = 0;

  osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits.get());

  osg::ref_ptr<osg::Camera> camera = new osg::Camera;

  camera->setGraphicsContext(gc.get());

  camera->setViewport(new osg::Viewport(0,0, traits->width, traits->height));

  GLenum buffer = traits->doubleBuffer ? GL_BACK : GL_FRONT;

  camera->setDrawBuffer(buffer);

  camera->setReadBuffer(buffer);

  // add this slave camera to the viewer, with a shift left of the projection matrix

  viewer->addSlave(camera.get());

 }

 osgUtil::Optimizer optimizer;

 optimizer.optimize(loadedModel.get());

 viewer->setSceneData(loadedModel.get());

//viewer->setUpViewOnSingleScreen(0);//这里是单屏幕显示

 return viewer->run();