为了满足shapefile 编辑，实现键鼠对地理要素的增删改。

读取shapefile，用Geometry Feature FeatureNode绘制在osgEarth上；

自定义osgGA::GUIEventHandler，handle函数中监测osgGA::GUIEventAdapter::PUSH

之前疑惑在拾取，看过许多例子，比如：osgEarth 拾取示例，最后还是老老实实用的射线拾取（osgUtil::LineSegmentIntersector）

大佬们多多指点，在此做个记录。

①拾取选中的featureNode确定距离鼠标最近的顶点。

// 使用射线拾取，找到 FeatureNode
osg::ref_ptr<osgEarth::FeatureNode> FeatureEditorHandler::pickFeatureNode(osgViewer::View* view, float x, float y) {
    osg::ref_ptr<osgUtil::LineSegmentIntersector> intersector = new osgUtil::LineSegmentIntersector(osgUtil::Intersector::WINDOW, x, y);
    osgUtil::IntersectionVisitor iv(intersector);
    view->getCamera()->accept(iv);

    if (intersector->containsIntersections()) {
        // 获取所有交叉点
        auto intersections = intersector->getIntersections();

        double minDistance = std::numeric_limits<double>::max();
        osg::ref_ptr<osgEarth::FeatureNode> nearestFeatureNode = nullptr;

        for (const auto& intersection : intersections) {
            osg::NodePath  nodePath = intersection.nodePath;

            for (osg::Node* node : nodePath) {
                osg::Group* groupNode = dynamic_cast<osg::Group*>(node);
                if (groupNode) {
                    for (unsigned int i = 0; i < groupNode->getNumChildren(); ++i) {
                        osgEarth::FeatureNode* childFeatureNode = dynamic_cast<osgEarth::FeatureNode*>(groupNode->getChild(i));
                        if (childFeatureNode) {
                            Feature* feature = childFeatureNode->getFeature();
                            Geometry* geometry = feature->getGeometry();

                            if (geometry) {
                                // 将交叉点转换为地理坐标
                                GeoPoint _GeoPoint;
                                _GeoPoint.fromWorld(_mapNode->getMapSRS(), intersection.getWorldIntersectPoint());
                                osg::Vec3d clickPoint(_GeoPoint.x(), _GeoPoint.y(), _GeoPoint.z());

                                // 遍历顶点并找到与点击点最近的顶点
                                for (unsigned int j = 0; j < geometry->size(); ++j) {
                                    osg::Vec3d vertex = geometry->operator[](j);
                                    double distance = (vertex - clickPoint).length();

                                    if (distance < minDistance) {
                                        minDistance = distance;
                                        nearestFeatureNode = childFeatureNode;
                                        _nearestVertexIndex = j;  // 更新最近的顶点索引
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }

        return nearestFeatureNode;  // 返回最近的 FeatureNode
    }

    return nullptr;  // 未找到返回空
}

②修改顶点

// 更新几何体的顶点位置
void FeatureEditorHandler::updateFeatureGeometry( osgViewer::View* view, osgEarth::FeatureNode* featureNode, float x, float y) {
    osg::Vec3d worldPos = screenToWorld(view, x, y);  // 将屏幕坐标转换为世界坐标

    if (featureNode) {
        osgEarth::Geometry* geometry = featureNode->getFeature()->getGeometry();
        if (geometry) {

            int iCnt = geometry->size();

            GeoPoint _GeoPoint;

            _GeoPoint.fromWorld(_mapNode->getMapSRS(), worldPos);

            // qDebugV5()<<"_nearestVertexIndex："<<_nearestVertexIndex;

            if(_nearestVertexIndex>=0 &&_nearestVertexIndex<iCnt){
                // 修改几何体的第一个顶点（可以根据需求修改其他顶点）
                geometry->at(_nearestVertexIndex) = osg::Vec3d(_GeoPoint.x(), _GeoPoint.y(), _GeoPoint.z());

                // 更新FeatureNode
                featureNode->dirty();
            }
            else{
                //qDebugV5()<<"_nearestVertexIndex 不合理：";
            }
        }
    }
}

③删除顶点

// 删除选中的 FeatureNode
void FeatureEditorHandler::deleteFeatureNode(osgEarth::FeatureNode* featureNode) {

    _mapNode->removeChild(featureNode);

}