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

<div class="titlepage"></div>

<div class="refnamediv">

<h2>Name</h2>

<p>faceforward — return a vector pointing in the same direction as another</p>

</div>

<div class="refsynopsisdiv">

<h2>Declaration</h2>

<div class="funcsynopsis">

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

<tr>

<td>

<code class="funcdef">genType <strong class="fsfunc">faceforward</strong>(</code>

</td>

<td>genType <var class="pdparam">N</var>, </td>

</tr>

<tr>

<td> </td>

<td>genType <var class="pdparam">I</var>, </td>

</tr>

<tr>

<td> </td>

<td>genType <var class="pdparam">Nref</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>N</code>

</em>

</span>

</dt>

<dd>

<p>

Specifies the vector to orient.

</p>

</dd>

<dt>

<span class="term">

<em class="parameter">

<code>I</code>

</em>

</span>

</dt>

<dd>

<p>

Specifies the incident vector.

</p>

</dd>

<dt>

<span class="term">

<em class="parameter">

<code>Nref</code>

</em>

</span>

</dt>

<dd>

<p>

Specifies the reference vector.

</p>

</dd>

</dl>

</div>

</div>

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

<h2>Description</h2>

<p>

<code class="function">faceforward</code> orients a vector to point away from a surface as defined by its normal.

If <a class="citerefentry" href="dot"><span class="citerefentry"><span class="refentrytitle">dot</span></span></a><code class="code">(<em class="parameter"><code>Nref</code></em>, <em class="parameter"><code>I</code></em>) &lt; 0</code>

<code class="function">faceforward</code> returns <em class="parameter"><code>N</code></em>, otherwise it returns <code class="code">-<em class="parameter"><code>N</code></em></code>.

</p>

</div>

{$pipelinestall}{$examples}

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

<h2>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 Shading Language 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>1.00</strong></span>

</th>

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

<span class="bold"><strong>3.00</strong></span>

</th>

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

<span class="bold"><strong>3.10</strong></span>

</th>

</tr>

</thead>

<tbody>

<tr>

<td style="text-align: left; border-right: 2px solid ; ">faceforward (genType)</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="reflect"><span class="citerefentry"><span class="refentrytitle">reflect</span></span></a>,

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

</p>

</div>

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

<h2>Copyright</h2>

<p>

Copyright © 2011-2014 Khronos Group.

This material may be distributed subject to the terms and conditions set forth in

the Open Publication License, v 1.0, 8 June 1999.

<a class="link" href="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.

</p>

</div>

</div>