A RenderTexture is not a texture, it creates a texture as a result of draw calls. You cannot play with the internal texture; you're not even supposed to know that there's one, it could perfectly be created only when you call getTexture().
Okay, good, so my assumption was correct, there is a technical reason the texture reference is const only.
It's not really a show stopper or anything. I just thought I could be a little bit more efficient.
I don't know why all your textures have to be a render-target, but this is not how the RenderTexture class is meant to be used. Maybe you could explain us what you do with textures?
Well, I need to implement
this interface. At first I was going to use sf::Image for it, but for a couple reasons (ie. stretched blitting, text rendering, hue shifting) it is more efficient to do everything directly on the GPU.
Edit: Oh, almost forgot. Is there a way to render the results of a RenderTexture in repeat mode,
without creating a copy of the internal texture everytime?