osg学习（四十四）读取earth文件的几种方式

1、

osg::Group* node = MapNodeHelper().load(arguments, &viewer);

2、

    osg::ref_ptr<osgDB::Options> myReadOptions = osgEarth::Registry::cloneOrCreateOptions(0);
    Config c;
    c.add("elevation_smoothing", false);
    TerrainOptions to(c);
    MapNodeOptions defMNO;
    defMNO.setTerrainOptions( to );
    myReadOptions->setPluginStringData("osgEarth.defaultOptions", defMNO.getConfig().toJSON());
    osg::ref_ptr<osg::Node> node = osgDB::readNodeFile("D:\\OSG_OAGEARTH_x86\\tests\\mb_tiles_test.earth",myReadOptions);

还可以进一步简化为

    osg::ref_ptr<osgDB::Options> myReadOptions = osgEarth::Registry::cloneOrCreateOptions(0);    
    osg::ref_ptr<osg::Node> node = osgDB::readNodeFile("D:\\OSG_OAGEARTH_x86\\tests\\mb_tiles_test.earth",myReadOptions);

第二种方法的viewpoints显示不出来，