为什么这儿可以重复定义？
看，InteractiveManipulator *cam 不是定义了两次？
if(pluginManager->getInputPlugin()->loaded())
{
InteractiveManipulator *cam = ((InteractiveManipulator*)camera.get());
cam->setPanLeftButton(5);
}
callbackManager->registerCallback(new KeyboardCallback<TestEnvironment>(this, &TestEnvironment::rightCallback, osgGA::GUIEventAdapter::KEYDOWN, '4', 1.0));
InteractiveManipulator *cam = dynamic_cast<InteractiveManipulator*>(camera.get());
