Creating procedural texture to pass into shader

[Xorboo]

I’m planning to create a color swap shader for sprites (something like this). For this to work i have to procedurally create a bunch of 1x256 textures, in which i could randomize pixel colors from code.
Currently i managed to find following stuff:

1. gui.new_texture and gui.set_texture_data, which are for gui and i suppose there are no way to pass them to sprite shader?
2. render.render_target, which, if i understand correctly, will create a texture, but will draw the scene into it, so i can’t change pixels there.

Is it actually not possible to procedurally create the texture? Or any other way to do randomizable color swapping on sprites?

[Yaroslav_Kravtsov]

Yes, it can be very useful to have an option to manipulate with color tables on the fly. Like old games doing it. And avoid resource duplicating.