I'd like to create a window with transparent background and then render something onto it using OpenGL. I don't want to use the trick where whatever is behind the window is captured and then painted as a background - I want real transparency (I have composition manager running). I'm not using any GUI library (GTK, QT, ...), just raw xlib and glx.
Anyone knows how to do it?
Take a look at these patches to Neverball and SDL. They seem to be based on NVidia's driver documentation.
I haven't tried it, but it looks as if you just select the correct GLX config (GLX_RGBA_BIT), clear your window appropriately, and have a compositor running, it should Just Work™.
来源：https://stackoverflow.com/questions/4066245/how-to-create-opengl-enabled-window-with-transparent-background-using-xlib-and-g