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<title>gl_FragDepth - OpenGL 4 Reference Pages</title>
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<div class="refentry" id="gl_FragDepth">
<div class="titlepage"/>
<div class="refnamediv">
<h2>Name</h2>
<p>gl_FragDepth — establishes a depth value for the current fragment</p>
</div>
<div class="refsynopsisdiv">
<h2>Declaration</h2>
<code class="fieldsynopsis"><span class="modifier">out </span><span class="type">float </span><span class="varname">gl_FragDepth </span>;</code>
</div>
<div class="refsect1" id="description">
<h2>Description</h2>
<p>
Available only in the fragment language, <code class="varname">gl_FragDepth</code> is an output variable
that is used to establish the depth value for the current fragment. If depth buffering is enabled
and no shader writes to <code class="varname">gl_FragDepth</code>, then the fixed function value for
depth will be used (this value is contained in the z component of <a class="citerefentry" href="gl_FragCoord.xhtml"><span class="citerefentry"><span class="refentrytitle">gl_FragCoord</span></span></a>)
otherwise, the value written to <code class="varname">gl_FragDepth</code> is used.
If a shader statically assigns to <code class="varname">gl_FragDepth</code>, then the value of the fragment's depth
may be undefined for executions of the shader that take that path. That is, if the set of linked fragment
shaders statically contain a write to <code class="varname">gl_FragDepth</code>, then it is responsible for always
writing it.
</p>
</div>
<div class="refsect1" id="versions">
<h2>Version Support</h2>
<div class="informaltable">
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<span class="bold"><strong>Variable Name</strong></span>
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<span class="bold"><strong>1.10</strong></span>
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<span class="bold"><strong>1.20</strong></span>
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<span class="bold"><strong>4.10</strong></span>
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<span class="bold"><strong>4.20</strong></span>
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<span class="bold"><strong>4.30</strong></span>
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<span class="bold"><strong>4.40</strong></span>
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<span class="bold"><strong>4.50</strong></span>
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<td style="text-align: left; border-right: 2px solid ; ">gl_FragDepth</td>
<td style="text-align: center; border-right: 2px solid ; ">✔</td>
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<td style="text-align: center; ">✔</td>
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<div class="refsect1" id="seealso">
<h2>See Also</h2>
<p>
<a class="citerefentry" href="gl_FragCoord.xhtml"><span class="citerefentry"><span class="refentrytitle">gl_FragCoord</span></span></a>
</p>
</div>
<div class="refsect1" id="Copyright">
<h2>Copyright</h2>
<p>
Copyright <span class="trademark"/>© 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="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
</p>
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