I am unable to find an answer to my question, because apparently it's not well enough defined to separate itself from a similar one. So I have to ask here.
My problem is quite simple. I have multiple shaderpasses and want to render each output into the same texture, which apparently isn't possible even using discard to, ahem, discard empty pixels each shaderpass isn't rendering to anyway. Each pass is supposed to only draw its own part to the texture.
I can use other methods of rendering only the necessary parts. I picked "discard", because it was the quickest to implement... and it's probably a bad idea compared to stencil.
Anyhow: The output-texture only contains one pass, which means it works, but not how I hoped.
Is it even possible to render multiple shaderpasses to the same texture without having each pass overwrite the output of the preceding pass?
And if it is... how?