'\"! eqn | mmdoc
'\"macro stdmacro
.ds Vn Version 1.2
.ds Dt 6 March 1997
.ds Re Release 1.1.0
.ds Dp Mar 17 18:08
.ds Dm  Mar  6 20:0
.ds Xs 53287 5 readbuffer.gl
.TH GLREADBUFFER
.SH NAME
.B "glReadBuffer
\- select a color buffer source for pixels

.SH C SPECIFICATION
void \f3glReadBuffer\fP(
GLenum \fImode\fP )
.nf
.fi

.SH PARAMETERS
.TP \w'\f2mode\fP\ \ 'u 
\f2mode\fP
Specifies a color buffer.
Accepted values are
\f3GL_FRONT_LEFT\fP,
\f3GL_FRONT_RIGHT\fP,
\f3GL_BACK_LEFT\fP,
\f3GL_BACK_RIGHT\fP,
\f3GL_FRONT\fP,
\f3GL_BACK\fP,
\f3GL_LEFT\fP,
\f3GL_RIGHT\fP, and
\f3GL_AUX\fP\f2i\fP,
where \f2i\fP is between 0 and \f3GL_AUX_BUFFERS\fP \-1.
.SH DESCRIPTION
\f3glReadBuffer\fP specifies a color buffer as the source for subsequent
\f3glReadPixels\fP, \f3glCopyTexImage1D\fP, \f3glCopyTexImage2D\fP,
\f3glCopyTexSubImage1D\fP, \f3glCopyTexSubImage2D\fP, and
\f3glCopyPixels\fP commands. 
\f2mode\fP accepts one of twelve or more predefined values.
(\f3GL_AUX0\fP through \f3GL_AUX3\fP are always defined.)
In a fully configured system,
\f3GL_FRONT\fP,
\f3GL_LEFT\fP, and
\f3GL_FRONT_LEFT\fP all name the front left buffer,
\f3GL_FRONT_RIGHT\fP and
\f3GL_RIGHT\fP name the front right buffer, and
\f3GL_BACK_LEFT\fP and
\f3GL_BACK\fP name the back left buffer.
.P
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 \f3glReadBuffer\fP.
.P
\f2mode\fP is initially \f3GL_FRONT\fP in single-buffered configurations,
and \f3GL_BACK\fP in double-buffered configurations.
.SH ERRORS
\f3GL_INVALID_ENUM\fP is generated if \f2mode\fP is not one of the twelve
(or more) accepted values.
.P
\f3GL_INVALID_OPERATION\fP is generated if \f2mode\fP specifies a buffer
that does not exist.
.P
\f3GL_INVALID_OPERATION\fP is generated if \f3glReadBuffer\fP
is executed between the execution of \f3glBegin\fP
and the corresponding execution of \f3glEnd\fP.
.SH ASSOCIATED GETS
\f3glGet\fP with argument \f3GL_READ_BUFFER\fP
.SH SEE ALSO
\f3glCopyPixels\fP,
\f3glCopyTexImage1D\fP,
\f3glCopyTexImage2D\fP,
\f3glCopyTexSubImage1D\fP,
\f3glCopyTexSubImage2D\fP,
\f3glDrawBuffer\fP,
\f3glReadPixels\fP