# Method GL.glReadBuffer()

Method glReadBuffer

  `void glReadBuffer(int mode)`

Description

  glReadBuffer specifies a color buffer as the source for subsequent glReadPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, 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.

Parameter `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_AUXi, where i is between 0 and GL_AUX_BUFFERS -1.

Throws

  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.