- select a color buffer source for pixels



C SPECIFICATION


PARAMETERS

       _param1  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.   _param1  accepts  one of twelve or more prede-
       fined  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 configura-
       tions 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.

       _param1  is initially GL_FRONT in single-buffered configu-
       rations, and GL_BACK in double-buffered configurations.


ERRORS

       GL_INVALID_ENUM is generated if _param1 is not one of  the
       twelve (or more) accepted values.

       GL_INVALID_OPERATION  is  generated if _param1 specifies a
       buffer that does not exist.

       GL_INVALID_OPERATION is generated if glReadBuffer is  exe-
       cuted between the execution of glBegin and the correspond-
       ing execution of glEnd.


ASSOCIATED GETS

       glGet with argument GL_READ_BUFFER


SEE ALSO

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