glReadBuffer
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## Name

glReadBuffer — select a color buffer source for pixels

## C Specification

`void `glReadBuffer`` | `(` | `GLenum `mode`);`

## Python Specification

``glReadBuffer`` | `(` | ``mode`) → `None``

## Parameters

`mode`
  Specifies 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.

## Description

`glReadBuffer` specifies a color buffer as the source for subsequent `glReadPixels`, `glCopyTexImage1D`, `glCopyTexImage2D`, `glCopyTexSubImage1D`, `glCopyTexSubImage2D`, `glCopyTexSubImage3D`, and `glCopyPixels` commands. `mode` 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`.

`mode` is initially `GL_FRONT` in single-buffered configurations, and `GL_BACK` in double-buffered configurations.

## Errors

`GL_INVALID_ENUM` is generated if `mode` is not one of the twelve (or more) accepted values.

`GL_INVALID_OPERATION` is generated if `mode` specifies a buffer that does not exist.

`GL_INVALID_OPERATION` is generated if `glReadBuffer` is executed between the execution of `glBegin` and the corresponding execution of `glEnd`.

## Associated Gets

`glGet` with argument `GL_READ_BUFFER`

## See Also

glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glDrawBuffer, glReadPixels

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