Three.js
 

Hi,

How to make sure that I could rendering 3D graphic using three.js.?

This is not a Sigil question at all. 3-D rendering would not be supported the majority of e-readers. You should be asking this question on the three.js website.

What I meant from the my previous posting, is that javascript with three.js can be integrated in sigil? If it can be integrated in sigil, how to make it?

Same way you would any javascript with any browser but it won't help as Sigil's Preview javascript is limited. Again 3D-animation will not be supported by most readers so I would not bother with it. So use it with Electron or a browser, not Sigil.

And all of this is discussed on the three.js website. This is not the right place for this discussion.