<div class="refentry" id="glClear">

<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 style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">

<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" id="parameters">

<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.

The three 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" id="description">

<h2>Description</h2>

<p>

<code class="function">glClear</code> sets the bitplane area of the window to values previously selected

by <code class="function">glClearColor</code>, <code class="function">glClearDepthf</code>, and

<code class="function">glClearStencil</code>.

Multiple color buffers can be cleared simultaneously by selecting

more than one buffer at a time using <a class="citerefentry" href="glDrawBuffers"><span class="citerefentry"><span class="refentrytitle">glDrawBuffers</span></span></a>.

</p>

<p>

The pixel ownership test,

the scissor test,

sRGB conversion,

dithering, and the buffer writemasks affect the operation of <code class="function">glClear</code>.

The scissor box bounds the cleared region.

Alpha function,

blend function,

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 buffers currently enabled for color

writing.

</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" id="notes">

<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" id="errors">

<h2>Errors</h2>

<p>

<code class="constant">GL_INVALID_VALUE</code> is generated if any bit other than the three defined

bits is set in <em class="parameter"><code>mask</code></em>.

</p>

</div>

<div class="refsect1" id="associatedgets">

<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_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_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_STENCIL_CLEAR_VALUE</code>

</p>

</div>

{$pipelinestall}{$examples}

<div class="refsect1" id="versions">

<h2>API Version Support</h2>

<div class="informaltable">

<table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">

<colgroup>

<col style="text-align: left; "/>

<col style="text-align: center; " class="firstvers"/>

<col style="text-align: center; "/>

<col style="text-align: center; " class="lastvers"/>

</colgroup>

<thead>

<tr>

<th style="text-align: left; border-right: 2px solid ; ">

</th>

<th style="text-align: center; border-bottom: 2px solid ; " colspan="3">

<span class="bold"><strong>OpenGL ES API Version</strong></span>

</th>

</tr>

<tr>

<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">

<span class="bold"><strong>Function Name</strong></span>

</th>

<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">

<span class="bold"><strong>2.0</strong></span>

</th>

<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">

<span class="bold"><strong>3.0</strong></span>

</th>

<th style="text-align: center; border-bottom: 2px solid ; ">

<span class="bold"><strong>3.1</strong></span>

</th>

</tr>

</thead>

<tbody>

<tr>

<td style="text-align: left; border-right: 2px solid ; ">glClear</td>

<td style="text-align: center; border-right: 2px solid ; ">✔</td>

<td style="text-align: center; border-right: 2px solid ; ">✔</td>

<td style="text-align: center; ">✔</td>

</tr>

</tbody>

</table>

</div>

</div>

<div class="refsect1" id="seealso">

<h2>See Also</h2>

<p>

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

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

<a class="citerefentry" href="glClearDepthf"><span class="citerefentry"><span class="refentrytitle">glClearDepthf</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="glDrawBuffers"><span class="citerefentry"><span class="refentrytitle">glDrawBuffers</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" id="Copyright">

<h2>Copyright</h2>

<p>

Copyright © 1991-2006 Silicon Graphics, Inc.

Copyright © 2010-2014 Khronos Group.

This document is licensed under the SGI Free Software B License.

For details, see

<a class="link" href="https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/" target="_top">https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/</a>.

</p>

</div>

</div>