Drawing elevation lines

[sebalaig]

Hi and thank you in advanced for your help.

I have a TMSElevationLayer, and I would like to display some contour lines for a given interval [altitudeMin, altitudeMax] with a given altitude interval, e.g drawing altitude lines between 0m and 1000m with a step of 200m.

Is there anything in osgearth to do that ? What class/set of class should I use ?

I try to overried FeatureSource and particularly the method createFeatureCursorImplementation, but this function is not called. Am I missing something. I set the tiled profile as the following :

Status ElevationContourFeatureSource::openImplementation()
{
    Status parent = FeatureSource::openImplementation();
    if (parent.isError())
        return parent;

    // Establish the feature profile.
    osg::ref_ptr<const Profile> globalGeodetic = Profile::create(Profile::GLOBAL_GEODETIC);

    const GeoExtent& extent = globalGeodetic->getExtent();
    FeatureProfile* profile = new FeatureProfile(extent);
    profile->setTilingProfile(Profile::create(extent.getSRS(), extent.xMin(), extent.yMin(), extent.xMax(), extent.yMax(), 1, 1));
    profile->setFirstLevel(_minLevel);
    profile->setMaxLevel(_maxLevel);

    setFeatureProfile(profile);

    return Status::NoError;
}

I'm using VTK to polygonize the altitude height map (in createFeatureCursorImplementation)

Thank you in advanced for you help 🙏 .