Referencing R0J0hound 's canvas plugin, you will find that
1. create a private canvas element
2. draw on this private canvas element
3. in "instanceProto.draw()", or "instanceProto.drawGL()", paste ctx of the private canvas element ( just copy these 2 functions )
- set variable "this.runtime.redraw", and "this.update_tex" to true to enable updating
I had tested fabric.js (add image) in C2, it worked.