DESCRIPTION
       Different  GL implementations buffer commands in several different loca‐
       tions, including network buffers and the  graphics  accelerator  itself.
       glFlush  empties all of these buffers, causing all issued commands to be
       executed as quickly as they are accepted by the actual rendering engine.
       Though  this  execution  may not be completed in any particular time pe‐
       riod, it does complete in finite time.

       Because any GL program might be executed over a network, or on an accel‐
       erator  that buffers commands, all programs should call glFlush whenever
       they count on having all of their previously issued commands  completed.
       For  example, call glFlush before waiting for user input that depends on
       the generated image.

NOTES
       glFlush can return at any time.  It does not wait until the execution of
       all previously issued GL commands is complete.

ERRORS
       GL_INVALID_OPERATION is generated if glFlush is executed between the ex‐
       ecution of glBegin and the corresponding execution of glEnd.

SEE ALSO
       glFinish

                                                                    GLFLUSH(3G)