X-Windows/XOpenDisplay question (Possibly a dumb one)

[CelticDaddio]

I am new to X-Windows/Linux programming, so this is probably a dumb question, but...

I am working on an application that only needs a valid GL context. I don't actually need visible rendering window. The example apps I have seen call XOpenDisplay to connect to the X-Server. Is this necessary to get a GL context?

CD

[Sykotik]

From the function reference, it seems that glXCreateContext does require a Display object, so you will have to call XOpenDisplay to get a display.

~P

[CelticDaddio]

Once I have a valid context, can I call XCloseDisplay and kill the server?

CD

From the function reference, it seems that glXCreateContext does require a Display object, so you will have to call XOpenDisplay to get a display.

~P

[Sykotik]

Once I have a valid context, can I call XCloseDisplay and kill the server?

I would say no. With GLX, the OpenGL commands/data are part of the X Window Specification proper (as an extension), so you actually do need the display to operate on your back-buffer. You'll probably only be able to close the connection to the X server once you're done with whatever you need to do with the OpenGL context.

Reason for this is the whole network transparency shebang of X, I think: execute the application on the server, have it display (or in your case, render in the off-screen pixmap) on the client -- that kind of thing.

Of course, I'm just speaking off the top of my head and from prior experience with X and/or OpenGL, so I'm open to being corrected.