I want to make application an application with a splash screen on Linux.
I want to use X11 and glx (OpenGL application).
I've found a way to remove the border around the window, but I can't find how to make it transparent. How can I accomplish this?
This is definitely something that you will want to offload to the GPU. I would not recommend directly using the X11 lib for performance reasons. Let OpenGL do it. I did find the following link for glXChooseVisual.
Also, here is another S.O. question that may be helpful.
Furthermore, this is for windows, but it should still apply.