Curtains / glass texture switch

[Tattooshop]

Hello! I'm trying to make a script for window curtains - a simple plane mesh and curtain texture. The curtains should "open / close" by click. but I don’t know how to do it better. I want to keep the ability to change the texture simply by applying a new texture to the windows. Thought to make a shift with a two halfs texture curtain / glass. But I have doubts about alpha blending...

 

Advise how else can be done?

 

Added: and if I do this option with a two halfs texture, how to shift from one half to the other?

Edited April 30, 2020 by Tattooshop