1991-2006 Silicon Graphics, Inc.

glXSwapBuffers

3G

glXSwapBuffers

exchange front and back buffers

# C Specification

                    void glXSwapBuffers
                    Display * dpy
                    GLXDrawable drawable

## Parameters

`dpy`

- Specifies the connection to the X server.

`drawable`

- Specifies the drawable whose buffers are to be swapped.

## Description

`glXSwapBuffers` promotes the contents of the back buffer of `drawable` to become the contents of the front buffer of `drawable`. The contents of the back buffer then become undefined. The update typically takes place during the vertical retrace of the monitor, rather than immediately after `glXSwapBuffers` is called.

`glXSwapBuffers` performs an implicit

glFlush

before it returns. Subsequent OpenGL commands may be issued immediately after calling `glXSwapBuffers`, but are not executed until the buffer exchange is completed.

If `drawable` was not created with respect to a double-buffered visual, `glXSwapBuffers` has no effect, and no error is generated.

## Notes

The contents of the back buffer become undefined after a swap. Note that this applies to pixel buffers as well as windows.

All GLX rendering contexts share the same notion of which are front buffers and which are back buffers. One consequence is that when multiple clients are rendering to the same double-buffered window, all of them should finish rendering before one of them issues the command to swap buffers. The clients are responsible for implementing this synchronization. Typically this is accomplished by executing

glFinish

and then using a semaphore in shared memory to rendezvous before swapping.

## Errors

`GLXBadDrawable` is generated if `drawable` is not a valid GLX drawable.

`GLXBadCurrentWindow` is generated if `dpy` and `drawable` are respectively the display and drawable associated with the current context of the calling thread, and `drawable` identifies a window that is no longer valid.

## See Also

glFlush

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.