osg三维场景修改相机视点失败，代码如下

唐朝

下面这段代码无法修改相机的视点：
        osgViewer::Viewer* OSGViewer = p3DRenderEngine->getViewer();
        osg::Node* sceneData = OSGViewer->getSceneData();
        osg::Group* root = dynamic_cast<osg::Group*>(sceneData);
        osg::Node* scene = root->getNumChildren() > 0 ? root->getChild(0) : nullptr;
        osg::ComputeBoundsVisitor boundVisitor;
        scene->accept(boundVisitor);
        osg::BoundingBox bb = boundVisitor.getBoundingBox();
        osg::Vec3d center = bb.center();
        double distance = bb.radius() * 2;
        osg::Vec3d target = osg::Vec3(center.x(), center.y(), 0);
        osg::Vec3d eye = target + osg::Vec3(0, 0, distance);
        osg::Vec3d up = osg::Vec3(0, 0, 1);
        OSGViewer->getCamera()->setViewMatrixAsLookAt(eye, target, up);
        OSGViewer->getCamera()->setProjectionMatrixAsOrtho(-distance, distance, -distance, distance, 1, 100);
下面这段代码可以：
        osg::Node* sceneData = OSGViewer->getSceneData();
        osg::Group* root = dynamic_cast<osg::Group*>(sceneData);
        osg::Node* scene = root->getNumChildren() > 0 ? root->getChild(0) : nullptr;
        osg::ComputeBoundsVisitor boundVisitor;
        scene->accept(boundVisitor);
        osg::BoundingBox bb = boundVisitor.getBoundingBox();
        osg::Vec3d center = bb.center();
        double distance = bb.radius() * 2;
        osg::Matrixd matrix;
        matrix.makeRotate(osg:uat(osg:I_2, osg::Vec3d(0, 0, 1)));
        matrix.preMultTranslate(osg::Vec3d(0, 0, distance));
        matrix.preMultScale(osg::Vec3d(1, 1, 1));
        OSGViewer->getCameraManipulator()->setByMatrix(matrix);
        osg::Matrixd projMatrix;
        projMatrix = osg::Matrixd:rtho2D(-distance, distance, -distance, distance);
        OSGViewer->getCamera()->setProjectionMatrix(projMatrix);
上面两端代码主要是为了实现俯视图的效果，但是仅仅通过相机来设置结果是不正确的，只有投影的效果，不管怎么该eye,target都没有作用!请教一下哪位大佬可以解答一下？