OsgEarth繪製多邊形，壓平多邊形區域的功能

osgEarth::Drivers::OGRFeatureOptions ogrData;
    osgEarth::Symbology::Polygon* Polygon = new osgEarth::Symbology::Polygon();
    Polygon->push_back(osg::Vec3d(106.047,37.59,5000));
    Polygon->push_back(osg::Vec3d(106.048,37.59,5000));
    Polygon->push_back(osg::Vec3d(106.072,37.60,5000));
    Polygon->push_back(osg::Vec3d(106.066,37.60,5000));
    ogrData.geometry() = Polygon;

    osgEarth::Util::FlatteningLayerOptions flaOption;
    flaOption.minLevel() = 11;
    flaOption.maxLevel() = 18;
    flaOption.name() = "Fla-Data";
    flaOption.featureSource() = ogrData;
    map->addLayer(new osgEarth::Util::FlatteningLayer(flaOption));

使用的是FlatteningLayer ，但是效果出不來？求大神解釋