Among examples of three.js, I want to change the teapot of material/nodes example to my obj file

The example uses NodeMaterials, but it is difficult to understand because the source code of the example is long and there is no way to use even if you try Googling. And this example uses the teapotBufferGeometry, and I want to use my obj file. Here’s the source code for the Material/nodes.

And another question is, can I use the obj called from the obj loader in Global?

Give me an advice.

I’m trying to this. but gui button is not working. what is matter to me? This is a live demo.