glReadBuffer(3G)

NAME
     glReadBuffer - select a color buffer source for pixels


C SPECIFICATION
     void glReadBuffer( GLenum mode )


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_AUXi, 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