<div class="refentry" title="glClear"><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" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glClear</b>(</code></td><td>GLbitfield <var class="pdparam">mask</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><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" title="Description"><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"><span class="citerefentry"><span class="refentrytitle">glClearColor</span></span></a>,

<a class="citerefentry" href="glClearDepth"><span class="citerefentry"><span class="refentrytitle">glClearDepth</span></span></a>,

and

<a class="citerefentry" href="glClearStencil"><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><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" title="Notes"><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" title="Errors"><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" title="Associated Gets"><a id="associatedgets"></a><h2>Associated Gets</h2><p>

<a class="citerefentry" href="glGet"><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"><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"><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" title="See Also"><a id="seealso"></a><h2>See Also</h2><p>

<a class="citerefentry" href="glClearColor"><span class="citerefentry"><span class="refentrytitle">glClearColor</span></span></a>,

<a class="citerefentry" href="glClearDepth"><span class="citerefentry"><span class="refentrytitle">glClearDepth</span></span></a>,

<a class="citerefentry" href="glClearStencil"><span class="citerefentry"><span class="refentrytitle">glClearStencil</span></span></a>,

<a class="citerefentry" href="glColorMask"><span class="citerefentry"><span class="refentrytitle">glColorMask</span></span></a>,

<a class="citerefentry" href="glDepthMask"><span class="citerefentry"><span class="refentrytitle">glDepthMask</span></span></a>,

<a class="citerefentry" href="glScissor"><span class="citerefentry"><span class="refentrytitle">glScissor</span></span></a>,

<a class="citerefentry" href="glStencilMask"><span class="citerefentry"><span class="refentrytitle">glStencilMask</span></span></a>

</p></div><div class="refsect1" title="Copyright"><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>