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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>glClear</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /></head><body><div class="refentry"><a id="glClear"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glClear — clear buffers to preset values</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glClear</strong>(</code></td><td>GLbitfield <var class="pdparam">mask</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term">
                    <em class="parameter"><code>mask</code></em>
                </span></dt><dd><p>Bitwise OR of masks that indicate the buffers to be
                    cleared. Valid masks are
                    <code class="constant">GL_COLOR_BUFFER_BIT</code>,
                    <code class="constant">GL_DEPTH_BUFFER_BIT</code>, and
                    <code class="constant">GL_STENCIL_BUFFER_BIT</code>.</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p>
        <code class="function">glClear</code>
        sets the bitplane area of the window to values previously selected by
        <a class="citerefentry" href="glClearColor.xml"><span class="citerefentry"><span class="refentrytitle">glClearColor</span></span></a>,
        <a class="citerefentry" href="glClearDepth.xml"><span class="citerefentry"><span class="refentrytitle">glClearDepth</span></span></a>,
        and
        <a class="citerefentry" href="glClearStencil.xml"><span class="citerefentry"><span class="refentrytitle">glClearStencil</span></span></a>.
        </p><p>The pixel ownership test, the scissor test, dithering,
        and the buffer write masks affect the operation of
        <code class="function">glClear</code>.
        The scissor box bounds the cleared region. Alpha function,
        blend function, logical operation, stenciling, texture mapping,
        and depth-buffering are ignored by <code class="function">glClear</code>.</p><p>
        <code class="function">glClear</code>
        takes a single argument that is the bitwise OR of several
        values indicating which buffer is to be cleared.</p><p>The values are as follows:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">
                    <code class="constant">GL_COLOR_BUFFER_BIT</code>
                </span></dt><dd><p>Indicates the color buffer.</p></dd><dt><span class="term">
                    <code class="constant">GL_DEPTH_BUFFER_BIT</code>
                </span></dt><dd><p>Indicates the depth buffer.</p></dd><dt><span class="term">
                    <code class="constant">GL_STENCIL_BUFFER_BIT</code>
                </span></dt><dd><p>Indicates the stencil buffer.</p></dd></dl></div><p>The value to which each buffer is cleared depends on the
        setting of the clear value for that buffer.</p></div><div class="refsect1"><a id="notes"></a><h2>Notes</h2><p>If a buffer is not present, then a <code class="function">glClear</code>
        directed at that buffer has no effect.</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_VALUE</code>
        is generated if any bit other than the defined bits is set in
        <em class="parameter"><code>mask</code></em>.</p></div><div class="refsect1"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_COLOR_CLEAR_VALUE</code>
        </p><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_DEPTH_CLEAR_VALUE</code>
        </p><p>
            <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_STENCIL_CLEAR_VALUE</code>
        </p></div><div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p>
        <a class="citerefentry" href="glClearColor.xml"><span class="citerefentry"><span class="refentrytitle">glClearColor</span></span></a>,
        <a class="citerefentry" href="glClearDepth.xml"><span class="citerefentry"><span class="refentrytitle">glClearDepth</span></span></a>,
        <a class="citerefentry" href="glClearStencil.xml"><span class="citerefentry"><span class="refentrytitle">glClearStencil</span></span></a>,
        <a class="citerefentry" href="glColorMask.xml"><span class="citerefentry"><span class="refentrytitle">glColorMask</span></span></a>,
        <a class="citerefentry" href="glDepthMask.xml"><span class="citerefentry"><span class="refentrytitle">glDepthMask</span></span></a>,
        <a class="citerefentry" href="glScissor.xml"><span class="citerefentry"><span class="refentrytitle">glScissor</span></span></a>,
        <a class="citerefentry" href="glStencilMask.xml"><span class="citerefentry"><span class="refentrytitle">glStencilMask</span></span></a>
        </p></div><div class="refsect1"><a id="copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 2003-2004
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></body></html>