glFlush function

Article
12/11/2020

The glFlush function forces execution of OpenGL functions in finite time.

Syntax

void WINAPI glFlush(void);

Parameters

This function has no parameters.

Return value

This function does not return a value.

Error codes

The following error code can be retrieved by the glGetError function.

Name	Meaning
GL_INVALID_OPERATION	The function was called between a call to glBegin and the corresponding call to glEnd.

Remarks

Different OpenGL implementations buffer commands in several different locations, including network buffers and the graphics accelerator itself. The glFlush function empties all 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 a finite amount of time.

Because any OpenGL program might be executed over a network, or on an accelerator that buffers commands, be sure to call glFlush in any programs requiring that all of their previously issued commands have been completed. For example, call glFlush before waiting for user input that depends on the generated image.

The glFlush function can return at any time. It does not wait until the execution of all previously issued OpenGL functions is complete.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Gl.h
Library	Opengl32.lib
DLL	Opengl32.dll