Requires shader files place in OpenSceneGraph-Data/shaders from OpenSceneGraph-Data's svn/trunk to function.
Run osgterrain example with --shader command line option to select displacement mapping shader approach.
git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14458 16af8721-9629-0410-8352-f15c8da7e697