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

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

<div class="refnamediv">

<h2>Name</h2>

<p>gl_SampleID — contains the index of the sample currently being processed</p>

</div>

<div class="refsynopsisdiv">

<h2>Declaration</h2>

<code class="fieldsynopsis"><span class="modifier">in </span><span class="type">int </span><span class="varname">gl_SampleID </span>;</code>

</div>

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

<h2>Description</h2>

<p>

<code class="varname">gl_SampleID</code> is a fragment language input variable that contains

the index of the sample currently being processed. This variable is in the range

0 to <a class="citerefentry" href="gl_NumSamples"><span class="citerefentry"><span class="refentrytitle">gl_NumSamples</span></span></a> - 1, where

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

is the total number of samples in each fragment for the current framebuffer (and thus 1 if

rendering to a non-multisample buffer). Any static use of this variable in a fragment

shader causes the entire shader to be evaluated per-sample rather than per-fragment.

</p>

<p>

When rendering to a non-multisample buffer, or if multisample rasterization is disabled,

<code class="varname">gl_SampleID</code> will always be zero. <a class="citerefentry" href="gl_NumSamples"><span class="citerefentry"><span class="refentrytitle">gl_NumSamples</span></span></a>

is the sample count of the framebuffer regardless of whether multisample rasterization is

enabled or not.

</p>

</div>

{$pipelinestall}{$examples}

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

<h2>Version Support</h2>

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<span class="bold"><strong>OpenGL Shading Language Version</strong></span>

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

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

<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>1.30</strong></span>

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<span class="bold"><strong>1.40</strong></span>

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<span class="bold"><strong>1.50</strong></span>

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<span class="bold"><strong>3.30</strong></span>

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<span class="bold"><strong>4.00</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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<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">

<span class="bold"><strong>4.30</strong></span>

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

<span class="bold"><strong>4.40</strong></span>

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

<span class="bold"><strong>4.50</strong></span>

</th>

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</thead>

<tbody>

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

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

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<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; border-right: 2px solid ; ">✔</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; 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="gl_SamplePosition"><span class="citerefentry"><span class="refentrytitle">gl_SamplePosition</span></span></a>,

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