osg鼠标点击获取经纬度

获取OSG场景中鼠标点击位置的经纬度可以通过以下步骤实现：

1. 获取窗口坐标系下鼠标点击位置：

osgViewer::Viewer* viewer = new osgViewer::Viewer;
// 设置鼠标事件处理程序
viewer->addEventHandler(new osgViewer::StatsHandler);
viewer->addEventHandler(new osgGA::StateSetManipulator(viewer->getCamera()->getOrCreateStateSet()));
viewer->addEventHandler(new osgViewer::WindowSizeHandler);
viewer->addEventHandler(new osgViewer::ThreadingHandler);
viewer->addEventHandler(new osgViewer::LODScaleHandler);
viewer->addEventHandler(new osgViewer::ScreenCaptureHandler);
viewer->addEventHandler(new osgViewer::RecordCameraPathHandler);
viewer->addEventHandler(new osgViewer::TabBoxHandler);
viewer->addEventHandler(new osgViewer::HelpHandler);
viewer->addEventHandler(new osgViewer::TrackballManipulator());
osg::ref_ptr<osgGA::GUIEventHandler> mouseHandler = new MouseHandler;
viewer->addEventHandler(mouseHandler);

// 定义自定义的鼠标事件处理程序
class MouseHandler : public osgGA::GUIEventHandler
{
public:
    virtual bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa)
    {
        if (ea.getEventType() == osgGA::GUIEventAdapter::PUSH)
        {
            float x = ea.getX(), y = ea.getY();
            // 获取窗口坐标系下的鼠标点击位置
            osg::ref_ptr<osgViewer::Viewer> viewer = dynamic_cast<osgViewer::Viewer*>(&aa);
            if (viewer.valid())
            {
                osg::ref_ptr<osg::Viewport> viewport = viewer->getCamera()->getViewport();
                x = viewport->x() + x;
                y = viewport->y() + y;
            }
            // ...
        }
        return false;
    }
};

2. 将窗口坐标系下的鼠标点击位置转换为场景坐标系下的位置：

osg::Vec3d worldPos;
osgUtil::LineSegmentIntersector::Intersections intersections;
if (viewer->computeIntersections(x, y, intersections))
{
    worldPos = intersections.begin()->getWorldIntersectPoint();
}

3. 将场景坐标系下的位置转换为经纬度：

// 获取当前视角下的经纬度
osgEarth::GeoPoint geoPoint;
if (viewer->getCamera()->getViewMatrixAsLookAt(geoPoint, osg::Vec3d(), osg::Vec3d(0, 0, 1)))
{
    // 获取场景坐标系下的局部坐标
    osg::Vec3d localPos = geoPoint.inverse(osgEarth::SpatialReference::get("wgs84")) * worldPos;
    // 将局部坐标转换为经纬度
    geoPoint.fromWorld(osgEarth::SpatialReference::get("wgs84"), worldPos);
    double lon = geoPoint.x(), lat = geoPoint.y();
}

这样就可以通过鼠标点击事件获取到OSG场景中的经纬度了。注意，前提是场景中已经加载了地球模型，并使用了osgEarth库进行地理坐标转换。