I found an easy way how to draw lines on the earth surface. It can be done with osgEarth::Symbology::MeshSubdivider, which subdivides (any?) geometry according to ellipsoid surface. It's very easy to use - just call one method on your geometry and specify wheter you want to interpolate according to great circle or not. ...I send screenshot (in attachment) of declaration of 25000km FAI triangle :-) T.
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