glReadBuffer(3)

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 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(3G),      glCopyTexImage1D(3G),      glCopyTexImage2D(3G),
       glCopyTexSubImage1D(3G),                       glCopyTexSubImage2D(3G),
       glCopyTexSubImage3D(3G), glDrawBuffer(3G), glReadPixels(3G)

                                                              GLREADBUFFER(3G)