OSG 裁剪回调

struct DrawableCullCallback : public osg::Drawable::CullCallback//自定义裁剪回调节点{/** do customized cull code.*/virtual bool cull(osg::NodeVisitor*, osg::Drawable* drawable, osg::State* /*state*/) const{std::cout<<"Drawable cull callback "<<drawable<<std::endl;return false;}};geode.getDrawable(i)->setCullCallback(new DrawableCullCallback());//为节点设置裁剪回调void ViewerBase::frame(double simulationTime){renderingTraversals();//从渲染回调更新开始} void ViewerBase::renderingTraversals(){for(Cameras::iterator camItr = cameras.begin();camItr != cameras.end();++camItr){osg::Camera* camera = *camItr;Renderer* renderer = dynamic_cast<Renderer*>(camera->getRenderer());if (renderer){if (!renderer->getGraphicsThreadDoesCull() && !(camera->getCameraThread())){renderer->cull();}}}} void Renderer::cull(){sceneView->cull();// osgUtil::SceneView* sceneView } void SceneView::cull(){bool computeNearFar = cullStage(getProjectionMatrix(),getViewMatrix(),_cullVisitor.get(),_stateGraph.get(),_renderStage.get(),getViewport());} bool SceneView::cullStage(const osg::Matrixd& projection,const osg::Matrixd& modelview,   osgUtil::CullVisitor* cullVisitor, osgUtil::StateGraph* rendergraph,   osgUtil::RenderStage* renderStage, osg::Viewport *viewport){// traverse the scene graph to generate the rendergraph.    // If the camera has a cullCallback execute the callback which has the  // requirement that it must traverse the camera's children.{osg::NodeCallback* callback = _camera->getCullCallback();if (callback) (*callback)(_camera.get(), cullVisitor);else cullVisitor->traverse(*_camera);}} inline void NodeVistor:: traverse(Node& node)//裁剪回调的Vistor{if (_traversalMode==TRAVERSE_PARENTS) node.ascend(*this);else if (_traversalMode!=TRAVERSE_NONE) node.traverse(*this);} inline void CullVisitor:: handle_cull_callbacks_and_traverse(osg::Node& node){osg::NodeCallback* callback = node.getCullCallback();//调用的Node的Callback，再经过一系列的过程，调用Node下Drawable的callback，如下if (callback) (*callback)(&node,this);else traverse(node);} void CullVisitor::apply(Geode& node){for(unsigned int i=0;i<node.getNumDrawables();++i){Drawable* drawable = node.getDrawable(i);const BoundingBox &bb =drawable->getBound();if( drawable->getCullCallback() ){if( drawable->getCullCallback()->cull( this, drawable, &_renderInfo ) == true )continue;}}  }virtual bool Drawable::cull(osg::NodeVisitor* nv, osg::Drawable* drawable, osg::RenderInfo* renderInfo) const{ return cull(nv, drawable, renderInfo? renderInfo->getState():0); }