PlaceNode is visible but not reachable when selecting

[AhmedAredah]

I have more than 800 point to show on the OSGEarthWidget. The widget is very slow if i added these 800 points of PlaceNode to the view root node directly so i group every 5~10 points under a new group node and add these group nodes to the root node. now, I want the user to be able to pick one of these PlaceNodes but it seems OSG does not find it by the IntersectionVisitor.
Below is a simplified version of the code

        osgViewer::Viewer::Views views;
        getOsgViewer()->getViews(views);
        for (auto view: views) {
                 PortClickHandler* clickHandler = PortClickHandler::getInstance();
                 view->addEventHandler(clickHandler);
         }
         
        // read in the Earth file:
        osg::ref_ptr<osg::Node> node =
            osgDB::readRefNodeFile(filename.toStdString());
        osg::Node* n = node.get();
        auto mapNode = osgEarth::MapNode::get(n);

        // a root node to hold everything:
        root->addChild(mapNode);

        // open the map node:
        if (!mapNode->open())
        {
            qDebug() << "Failed to open MapNode";
            return;
        } 

        osg::ref_ptr<osg::Group> parentGroup = new osg::Group();     // hold all labels groups
        osg::ref_ptr<osg::Group> countryGroup = new osg::Group();  // hold 5~10 labels

        // this is how i create the placeNode. detailed code is removed for clarification and reduce complexity 
        auto label = new osgEarth::PlaceNode(
                    osgEarth::GeoPoint(
                        geoSRS,
                        port->getPortCoordinate().getLongitude().value(),
                        port->getPortCoordinate().getLatitude().value(), 0,
                        osgEarth::AltitudeMode::ALTMODE_ABSOLUTE),
                    "custom name",
                    pm);
       label->setStyle(labelStyle);
       label->setName("Port");
       countryGroup->addChild(label);
       parentGroup->addChild(countryGroup);
       mapNode->addChild(parentGroup);   // add the labels group to the mapNode

----------------------------------------------------------------
        
class PortClickHandler : public QObject, public osgGA::GUIEventHandler
{
    Q_OBJECT
    bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)
    {
        if (ea.getEventType() == osgGA::GUIEventAdapter::RELEASE &&
            ea.getButton() == osgGA::GUIEventAdapter::LEFT_MOUSE_BUTTON)
        {
            osgViewer::View* view = dynamic_cast<osgViewer::View*>(&aa);
            if (view)
            {
                osg::ref_ptr<osgUtil::LineSegmentIntersector> intersector =
                    new osgUtil::LineSegmentIntersector(
                    osgUtil::Intersector::WINDOW, ea.getX(), ea.getY());

                osgUtil::IntersectionVisitor iv(intersector.get());
                iv.setTraversalMask(osg::Node::NodeMask(~0));
                view->getCamera()->accept(iv);
                if (intersector->containsIntersections())
                {
                    for (const auto& intersection :
                         intersector->getIntersections())
                    {
                        for (auto& node : intersection.nodePath) {
                            if (node) {
                                std::cout << "Node in Path: " << node->getName() << node->className() << std::endl;   // I do not get the port nodes that i added here when i click on the label on OSGEarth widget
                            }
                        }
                    }
                }
            }
        }
        return false; // Event not handled
    }
}

[gwaldron]

PlaceNodes (and other osgEarth annotations like LabelNodes) don't work with the OSG intersect visitor because they are screen-space objects. Instead you can try the osgEarth RTTPicker. There's example usage in the osgearth_pick application. Good luck.

[AhmedAredah]

Thank you.

[AhmedAredah]

@gwaldron , can i set the PlaceNode id to a value other than 0. I always get the id = 0 and then the function does not continue executing:
Also is there any documentation i can refer to in these little details? Thank you :)

         // when adding the PlaceNode label
         osgEarth::Registry::objectIndex()->tagNode(label, label);



        osgEarth::Util::ObjectIDPicker* picker = new ObjectIDPicker();
        picker->setView(getOsgViewer());
        picker->setGraph(preloadedMapRoot.get());
        preloadedMapRoot->addChild(picker);

        ObjectIDPicker::Function pick = [&](ObjectID id)
        {
            if (id > 0)
               std::cout << id;
        }

[gwaldron]

You don't set the ID yourself. tagNode will generate an ID and return it. If you are getting id==0 then something is not right. If you can provide a minimal example we can take a look.

Sorry - not really much documentation on this stuff besides the examples.