osg剔除背面开启

//设置背部剔除看不见背面东西
    osg::ref_ptr<osg::CullFace> cullface=new osg::CullFace(osg::CullFace::BACK);
    state->setAttribute(cullface.get());
    state->setMode(GL_CULL_FACE,osg::StateAttribute::ON);