I'm trying to create a fullscreen and transparent OpenGL window in XLib, with the purpose of applying shaders to the screen. Imagine applying a blur or pixelate effect, for example. For now, i'm trying to do something really simple, such as rendering the current date in the middle, blurring the background and that's it.
What's the appropriate setup for this? Should i capture the desktop when my app launches and use that as a bitmap to manipulate in my shader? Or should i actually make some kind of transparency protocol?