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 non‐
       stereo.  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

                                                               GLREADBUFFER(3G)