glFlush - force execution of GL commands in finite time

voidglFlush(void);

       Copyright © 1991-2006 Silicon Graphics, Inc.
       Copyright © 2010-2014 Khronos Group

[FIXME: source]                                    11/18/2024                                        GLFLUSH(3G)

       Different GL implementations buffer commands in several different locations, 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 period, it does complete in finite time.

       Because any GL program might be executed over a network, or on an accelerator 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.

       glFlush - force execution of GL commands in finite time

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

glFinish()

       ┌──────────┬───────────────────────────────────────────────────────────────────────┐
       │          │                OpenGLVersion                                         │
       ├──────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │ Function │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
       │ /        │     │     │     │     │     │     │     │     │     │     │     │     │
       │ Feature  │     │     │     │     │     │     │     │     │     │     │     │     │
       │ Name     │     │     │     │     │     │     │     │     │     │     │     │     │
       ├──────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │ glFlush  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       └──────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘