目標：（十七）中問題47

osgEarth/TerrainTileModelFactory.cpp
TerrainTileModel*
TerrainTileModelFactory::createTileModel(const MapFrame&                  frame,
                                         const TileKey&                   key,
                                         const CreateTileModelFilter&     filter,
                                         const TerrainEngineRequirements* requirements,
                                         ProgressCallback*                progress)
{
    // Make a new model:
    osg::ref_ptr<TerrainTileModel> model = new TerrainTileModel(
        key,
        frame.getRevision() );

    // assemble all the components:
    //addImageLayers(model.get(), frame, requirements, key, filter, progress);
    addColorLayers(model.get(), frame, requirements, key, filter, progress);

    addPatchLayers(model.get(), frame, key, filter, progress);

    if ( requirements == 0L || requirements->elevationTexturesRequired() )
    {
        unsigned border = requirements->elevationBorderRequired() ? 1u : 0u;

        addElevation( model.get(), frame, key, filter, border, progress );
    }

#if 0
    if ( requirements == 0L || requirements->normalTexturesRequired() )
    {
        addNormalMap( model.get(), frame, key, progress );
    }
#endif

    // done.
    return model.release();
}