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<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glIndexMask</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glIndexMask"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glIndexMask — control the writing of individual bits in the color index buffers</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><p><code class="funcdef">void <b class="fsfunc">glIndexMask</b>(</code>GLuint <var class="pdparam">mask</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="id4782015"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>mask</code></em></span></dt><dd><p>
                    Specifies a bit mask to enable and disable the writing of individual bits
                    in the color index buffers.
                    Initially, the mask is all 1's.
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="id4782046"></a><h2>Description</h2><p>
            <code class="function">glIndexMask</code> controls the writing of individual bits in the color index buffers.
            The least significant 
            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
            bits of <em class="parameter"><code>mask</code></em>,
            where 
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            is the number of bits in a color index buffer,
            specify a mask.
            Where a 1 (one) appears in the mask,
            it's possible to write to the corresponding bit in the color index
            buffer (or buffers).
            Where a 0 (zero) appears,
            the corresponding bit is write-protected.
        </p><p>
            This mask is used only in color index mode,
            and it affects only the buffers currently selected for writing
            (see <a href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>).
            Initially, all bits are enabled for writing.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="id4768520"></a><h2>Errors</h2><p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glIndexMask</code>
            is executed between the execution of <a href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
            and the corresponding execution of <a href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="id4768549"></a><h2>Associated Gets</h2><p>
            <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_INDEX_WRITEMASK</code>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="id4768566"></a><h2>See Also</h2><p>
            <a href="glColorMask.xml"><span class="citerefentry"><span class="refentrytitle">glColorMask</span></span></a>,
            <a href="glDepthMask.xml"><span class="citerefentry"><span class="refentrytitle">glDepthMask</span></span></a>,
            <a href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>,
            <a href="glIndex.xml"><span class="citerefentry"><span class="refentrytitle">glIndex</span></span></a>,
            <a href="glIndexPointer.xml"><span class="citerefentry"><span class="refentrytitle">glIndexPointer</span></span></a>,
            <a href="glStencilMask.xml"><span class="citerefentry"><span class="refentrytitle">glStencilMask</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="id4768606"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></body></html>
