Q:

How to load kml files into osgEarth using .earth file? 

I want to simply show some kml files with osgearth_viewer.exe. 
I've read the osgEarth documentation and get nothing about how to load a lot of KML files by using .earth file with osgearth_viewer.exe. 
I know how to load one kml file using comand line parameter --kml , but I wanna to show all kml files once. 
Any help would be gratefully appreciated and sorry for my poor English. 

A:

The example here: 
http://code.metager.de/source/xref/osgearth/src/applications/osgearth_kml/osgearth_kml.cpp#63
Shows pretty clearly how you do it.  Just do the 
        osg::Node* kml = osgDB::readNodeFile( kmlFile, options.get() );
        if ( kml )
            root->addChild( kml );

steps as many times as you want for as many KML files as you want.