Irrlicht - Using SMesh, SMeshBuffer and SceneManager->AddOctreeSceneNode(...)

I need to draw a very large number of 3d lines. If I use开发者_StackOverflow driver->draw3dLine(...), the performance drops very badly. I heard that using the Octree we can optimize the drawing by displaying only what we need to see but I'm confused as to how to use it to solve my problem.