glReadBuffer function

Article
12/11/2020

The glReadBuffer function selects a color buffer source for pixels.

Syntax

void WINAPI glReadBuffer(
   GLenum mode
);

Parameters

mode: A color buffer. Accepted values are GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, GL_BACK_RIGHT, GL_FRONT, GL_BACK, GL_LEFT, GL_RIGHT, and GL_AUX i, where i is between 0 and GL_AUX_BUFFERS 1.

Return value

This function does not return a value.

Error codes

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

Name	Meaning
GL_INVALID_ENUM	mode was not an one of the twelve (or more) accepted values.
GL_INVALID_OPERATION	mode specified a buffer that does not exist.
GL_INVALID_OPERATION	The function was called between a call to glBegin and the corresponding call to glEnd.

Remarks

The glReadBuffer function specifies a color buffer as the source for subsequent glReadPixels and glCopyPixels commands. The mode parameter accepts one of twelve or more predefined values. (GL_AUX0 through GL_AUX3 are always defined.) In a fully configured system, GL_FRONT, GL_LEFT, and GL_FRONT_LEFT all name the front-left buffer, GL_FRONT_RIGHT and GL_RIGHT name the front-right buffer, and GL_BACK_LEFT and GL_BACK name the back-left buffer.

Nonstereo double-buffered configurations have only a front-left and a back-left buffer. Single-buffered configurations have a front-left and a front-right buffer if stereo, and only a front-left buffer if nonstereo. It is an error to specify a nonexistent buffer to glReadBuffer.

By default, mode is GL_FRONT in single-buffered configurations, and GL_BACK in double-buffered configurations.

The following function retrieves information related to glReadBuffer:

glGet with argument GL_READ_BUFFER

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