New sf::RenderTexture is black

[jamesk]

I'm using the code from this example here:
https://github.com/SFML/SFML/wiki/Source:-HeatHazeShader

And I have the texture distorting correctly. Now I'm placing it in my scene and all alpha transparency is missing. The entire render target (besides the distorted sprite) is black. Without using blend modes is there a way to set the default texture buffer to transparent?

[eXpl0it3r]

Clear it with a transparent color and display it.

The default behavior is undefined.

[jamesk]

There's no way to clear it from the API:
https://www.sfml-dev.org/documentation/2.5.0/classsf_1_1RenderTexture.php

And the texture instance I get back would be read-only.

[eXpl0it3r]

What about the function called clear()?

[jamesk]

goddamnit