OSG绘制的部分流程(待修改完善)？？？？？？？？？？？？

void Viewer::updateTraversal()

{//主相机

if (_camera.valid() && _camera->getUpdateCallback()) _camera->accept(*_updateVisitor);

//从相机

for(unsigned int i=0; i<getNumSlaves(); ++i)

{  osg::Camera* camera = getSlave(i)._camera.get();

if (camera && camera->getUpdateCallback()) camera->accept(*_updateVisitor);

}

//主相机

if (_cameraManipulator.valid())

{ ……

_camera->setViewMatrix(_cameraManipulator->getInverseMatrix());

}

//从相机

updateSlaves();

}

void RenderStage::draw(osg::RenderInfo& renderInfo,RenderLeaf*& previous)

{

drawPreRenderStages(renderInfo,previous);

if (_camera && _camera->getPreDrawCallback())

    {

        // if we have a camera with a pre draw callback invoke it.

        (*(_camera->getPreDrawCallback()))(renderInfo);

    }

glFlush();

if (_camera && _camera->getPostDrawCallback())

    {

        // i