怎么将osgViewer::Viewer嵌入ui->openGLWidget

将 `osgViewer::Viewer` 嵌入到 `QOpenGLWidget` 中，可以通过以下步骤实现：

1. 继承 `QOpenGLWidget` 类，并实现以下虚函数：

class OsgWidget : public QOpenGLWidget, protected QOpenGLFunctions
{
public:
    OsgWidget(QWidget* parent = nullptr);
    virtual ~OsgWidget();

protected:
    void initializeGL() override;
    void resizeGL(int w, int h) override;
    void paintGL() override;
    void paintEvent(QPaintEvent* event) override;
    void keyPressEvent(QKeyEvent* event) override;
    void keyReleaseEvent(QKeyEvent* event) override;
    void mousePressEvent(QMouseEvent* event) override;
    void mouseReleaseEvent(QMouseEvent* event) override;
    void mouseMoveEvent(QMouseEvent* event) override;
    bool event(QEvent* event) override;
};

其中，`initializeGL`、`resizeGL` 和 `paintGL` 函数用于初始化 OpenGL 上下文并绘制场景，`paintEvent` 函数用于处理重绘事件，`keyPressEvent`、`keyReleaseEvent`、`mousePressEvent`、`mouseReleaseEvent` 和 `mouseMoveEvent` 函数用于处理键盘和鼠标事件，`event` 函数用于处理其他事件。

2. 在 `initializeGL` 函数中创建 `osgViewer::GraphicsWindow` 对象，并将其关联到 `osgViewer::Viewer` 对象中：

void OsgWidget::initializeGL()
{
    // Create an OSG graphics context
    osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
    traits->windowName = "OSG Widget";
    traits->x = 0;
    traits->y = 0;
    traits->width = width();
    traits->height = height();
    traits->doubleBuffer = true;
    traits->windowDecoration = false;
    traits->sharedContext = 0;

    // Create an OSG graphics window
    osg::ref_ptr<osgViewer::GraphicsWindow> gw = osg::GraphicsContext::createGraphicsWindow(traits.get());

    // Create an OSG viewer
    osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer;
    viewer->getCamera()->setGraphicsContext(gw);
    viewer->getCamera()->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));

    // Set the viewer's scene data
    osg::ref_ptr<osg::Node> scene = createSceneGraph();
    viewer->setSceneData(scene.get());

    // Save the viewer pointer for later use
    m_viewer = viewer;
}

其中，`createSceneGraph` 函数用于创建 OSG 场景图。

3. 在 `paintGL` 函数中将 `osgViewer::Viewer` 的帧缓冲区绑定到 `QOpenGLWidget` 的帧缓冲区，并使用 `osgViewer::Viewer::frame` 函数绘制一帧：

void OsgWidget::paintGL()
{
    // Bind OSG's frame buffer object to the OpenGL context
    m_viewer->getCamera()->getGraphicsContext()->realizeOpenGLContext();
    m_viewer->getCamera()->getGraphicsContext()->makeCurrent();
    m_viewer->getCamera()->getGraphicsContext()->bindPBufferToTexture();

    // Draw a frame
    m_viewer->frame();

    // Swap the buffers
    m_viewer->getCamera()->getGraphicsContext()->swapBuffers();
}

4. 在 `resizeGL` 函数中更新 `osgViewer::Viewer` 的视口：

void OsgWidget::resizeGL(int w, int h)
{
    // Update OSG's viewport
    m_viewer->getCamera()->setViewport(new osg::Viewport(0, 0, w, h));
}

5. 在 `paintEvent` 函数中强制刷新 `QOpenGLWidget`：

void OsgWidget::paintEvent(QPaintEvent* event)
{
    // Force redraw
    update();
}

6. 将 `OsgWidget` 添加到 `QMainWindow` 中：

int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    QMainWindow mainWindow;

    // Create an OSG widget
    OsgWidget* osgWidget = new OsgWidget(&mainWindow);

    // Add the OSG widget to the main window
    mainWindow.setCentralWidget(osgWidget);

    mainWindow.show();

    return app.exec();
}

通过以上步骤，就可以将 `osgViewer::Viewer` 嵌入到 `QOpenGLWidget` 中，并在 Qt 应用程序中显示 OSG 场景图了。