怎样设置投影矩阵

liyang2014

//得到cameraMaster(主相机)
        osg::ref_ptr<osg::Camera> cameraMaster = viewer->getCamera();
        //设置图形环境
        cameraMaster->setGraphicsContext(gc.get());

        //根据分辨率来确定合适的投影来保证显示的图形不变形
        double fovy, aspectRatio, zNear, zFar;
        cameraMaster->getProjectionMatrixAsPerspective(fovy, aspectRatio, zNear, zFar);
        double newAspectRatio = double(traits->width) / double(traits->height);
        double aspectRatioChange = newAspectRatio / aspectRatio;
        if (aspectRatioChange != 1.0)
        {
                cameraMaster->getProjectionMatrix() *= osg::Matrix::scale(1.0/aspectRatioChange,1.0,1.0);
        }

        //设置视口
        cameraMaster->setViewport(new osg::Viewport(0,0, width, height));
        GLenum bufferMaster = traits->doubleBuffer ? GL_BACK : GL_FRONT;
        //设置缓冲区
        cameraMaster->setDrawBuffer(bufferMaster);
        cameraMaster->setReadBuffer(bufferMaster);

        //创建从属相机
        osg::ref_ptr<osg::Camera> cameraClient = new osg::Camera();
        cameraClient->setGraphicsContext(gc.get());
        cameraClient->setViewport(new osg::Viewport(0,0, 400, 400));
        GLenum bufferClient = traits->doubleBuffer ? GL_BACK : GL_FRONT;
        cameraClient->setDrawBuffer(bufferClient);
        cameraClient->setReadBuffer(bufferClient);

        //添加从属相机
        viewer->addSlave(cameraClient,osg::Matrix::scale(aspectRatio,1.0,1.0),osg::Matrix()) ;

liyang2014

为什么主摄像机设置投影矩阵，从摄像机不用设置投影矩阵呢
osg编程指南有一段话：
如果View仅仅有一个主相机，则该主相机用来负责控制和渲染视图场景。如果包含从属相机，则主相机用来负责控制管理视图，则从相机用于渲染场景。
管理视图和渲染场景分别是做什么的？体现在哪部分？

liyang2014

动鼠标，2个视图跟着动？