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<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glDrawBuffer">
    <info>
        <copyright>
            <year>1991-2006</year>
            <holder>Silicon Graphics, Inc.</holder>
        </copyright>
        <copyright>
            <year>2010-2013</year>
            <holder>Khronos Group</holder>
        </copyright>
    </info>
    <refmeta>
        <refentrytitle>glDrawBuffer</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glDrawBuffer</refname>
        <refpurpose>specify which color buffers are to be drawn into</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glDrawBuffer</function></funcdef>
                <paramdef>GLenum <parameter>mode</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 xml:id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>mode</parameter></term>
            <listitem>
                <para>
                    Specifies up to four color buffers to be drawn into.
                    Symbolic constants
                    <constant>GL_NONE</constant>,
                    <constant>GL_FRONT_LEFT</constant>,
                    <constant>GL_FRONT_RIGHT</constant>,
                    <constant>GL_BACK_LEFT</constant>,
                    <constant>GL_BACK_RIGHT</constant>,
                    <constant>GL_FRONT</constant>,
                    <constant>GL_BACK</constant>,
                    <constant>GL_LEFT</constant>,
                    <constant>GL_RIGHT</constant>, and
                    <constant>GL_FRONT_AND_BACK</constant>
                    are accepted.
                    The initial value is <constant>GL_FRONT</constant> for single-buffered contexts,
                    and <constant>GL_BACK</constant> for double-buffered contexts.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 xml:id="description"><title>Description</title>
        <para>
            When colors are written to the frame buffer,
            they are written into the color buffers specified by <function>glDrawBuffer</function>.
            The specifications are as follows:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_NONE</constant></term>
                <listitem>
                    <para>
                        No color buffers are written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_FRONT_LEFT</constant></term>
                <listitem>
                    <para>
                        Only the front left color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_FRONT_RIGHT</constant></term>
                <listitem>
                    <para>
                        Only the front right color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BACK_LEFT</constant></term>
                <listitem>
                    <para>
                        Only the back left color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BACK_RIGHT</constant></term>
                <listitem>
                    <para>
                        Only the back right color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_FRONT</constant></term>
                <listitem>
                    <para>
                        Only the front left and front right color buffers are written.
                        If there is no front right color buffer,
                        only the front left color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_BACK</constant></term>
                <listitem>
                    <para>
                        Only the back left and back right color buffers are written.
                        If there is no back right color buffer,
                        only the back left color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_LEFT</constant></term>
                <listitem>
                    <para>
                        Only the front left and back left color buffers are written.
                        If there is no back left color buffer,
                        only the front left color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_RIGHT</constant></term>
                <listitem>
                    <para>
                        Only the front right and back right color buffers are written.
                        If there is no back right color buffer,
                        only the front right color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_FRONT_AND_BACK</constant></term>
                <listitem>
                    <para>
                        All the front and back color buffers
                        (front left, front right, back left, back right)
                        are written.
                        If there are no back color buffers,
                        only the front left and front right color buffers are written.
                        If there are no right color buffers,
                        only the front left and back left color buffers are written.
                        If there are no right or back color buffers,
                        only the front left color buffer is written.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
            If more than one color buffer is selected for drawing,
            then blending or logical operations are computed and applied independently
            for each color buffer and can produce different results in each buffer.
        </para>
        <para>
            Monoscopic contexts include only
            <emphasis>left</emphasis>
            buffers, and stereoscopic contexts include both
            <emphasis>left</emphasis>
            and
            <emphasis>right</emphasis>
            buffers.
            Likewise, single-buffered contexts include only
            <emphasis>front</emphasis>
            buffers, and double-buffered contexts include both
            <emphasis>front</emphasis>
            and
            <emphasis>back</emphasis>
            buffers.
            The context is selected at GL initialization.
        </para>
    </refsect1>
    <refsect1 xml:id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not an accepted value.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if none of the buffers indicated
            by <parameter>mode</parameter> exists.
        </para>
    </refsect1>
    <refsect1 xml:id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DRAW_BUFFER</constant>
        </para>
    </refsect1>
    <refsect1 xml:id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBlendFunc</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glColorMask</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawBuffers</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glLogicOp</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glReadBuffer</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 xml:id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"/> 1991-2006 Silicon Graphics, Inc.
            Copyright <trademark class="copyright"/> 2010-2013 Khronos Group.
            This document is licensed under the SGI Free Software B License.
            For details, see
            <link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</link>.
        </para>
    </refsect1>
</refentry>
