How to create a custom texture from a scene?

Question

Hello, I have a scene composed of several Node2Ds. Each of them are parent of several Sprites. The goal of my scene is to add variety by randomly showing a Sprite for each Node2D, and hiding the others.
Here is an example :

I would like to save the result as a texture, to repeat in a Polygon2D from my main scene.
However, I don't want to show the scene, then I cannot use get_viewport().get_screen_capture().

Do you have any idea on how to save the result as a texture ?

If I can't figure out a way, I will launch the scene and take several screenshots to reuse them afterwhile, but I'd like to do it by code ;)
Thank you :)

Comments

http://www.godotengine.org/qa/3313/capture-frame-and-show-it-as-sprite
http://www.godotengine.org/qa/2116/how-to-draw-a-mask-on-a-sprite

it doesn't help?

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Thank you, I already tried the first method, which is not quite adapted, because of "getscreencapture()"

However the second one seems interesting, I will try it tonight and keep you advised :)

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have you ever got anywhere with this? might answer your own question for posterity.

I'm wondering how to draw a custom texture from the ground up, however without using _draw.