glFlush — force execution of GL commands in finite time
void glFlush( | void) ; |
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
can return at any time.
It does not wait until the execution of all previously
issued GL commands is complete.
GL_INVALID_OPERATION
is generated if glFlush
is executed between the execution of glBegin
and the corresponding execution of glEnd.
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