when scene is really rendered out using three.js

问题

I'm making a progress bar such as "loading" in a scene with three.js. But when is the scene really loaded?Render is doing its work all the time and the Loader's callback option just work when the images get loaded from network.And i can't find a callback function option where the scene is really loaded or rendered out. So where or when is the callback function should be called?

来源：https://stackoverflow.com/questions/28229618/when-scene-is-really-rendered-out-using-three-js