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glBeginTransformFeedback.xhtml
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<div class="refentry" id="glBeginTransformFeedback">
<div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>glBeginTransformFeedback — start transform feedback operation</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">glBeginTransformFeedback</strong>(</code>
</td>
<td>GLenum <var class="pdparam">primitiveMode</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
</div>
<div class="funcsynopsis">
<table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
<tr>
<td>
<code class="funcdef">void <strong class="fsfunc">glEndTransformFeedback</strong>(</code>
</td>
<td><var class="pdparam">void</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
</div>
</div>
<div class="refsect1" id="parameters">
<h2>Parameters for <code class="function">glBeginTransformFeedback</code></h2>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<em class="parameter">
<code>primitiveMode</code>
</em>
</span>
</dt>
<dd>
<p>
Specify the output type of the primitives that will be recorded into the
buffer objects that are bound for transform feedback.
</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="description">
<h2>Description</h2>
<p>
Transform feedback mode captures the values of varying variables written by the vertex shader (or, if active, the geometry shader).
Transform feedback is said to be active after a call to <code class="function">glBeginTransformFeedback</code>
until a subsequent call to <a class="citerefentry" href="glEndTransformFeedback"><span class="citerefentry"><span class="refentrytitle">glEndTransformFeedback</span></span></a>.
Transform feedback commands must be paired.
</p>
<p>
If no geometry shader is present, while transform feedback is active the <em class="parameter"><code>mode</code></em> parameter to
<a class="citerefentry" href="glDrawArrays"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a> must match those specified
in the following table:
</p>
<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: left; "/>
</colgroup>
<thead>
<tr>
<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>
Transform Feedback <em class="parameter"><code>primitiveMode</code></em>
</strong></span>
</th>
<th style="text-align: left; border-bottom: 2px solid ; ">
<span class="bold"><strong>
Allowed Render Primitive <em class="parameter"><code>modes</code></em>
</strong></span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; "> <code class="constant">GL_POINTS</code> </td>
<td style="text-align: left; border-bottom: 2px solid ; "> <code class="constant">GL_POINTS</code> </td>
</tr>
<tr>
<td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; "> <code class="constant">GL_LINES</code> </td>
<td style="text-align: left; border-bottom: 2px solid ; ">
<code class="constant">GL_LINES</code>,
<code class="constant">GL_LINE_LOOP</code>,
<code class="constant">GL_LINE_STRIP</code>,
<code class="constant">GL_LINES_ADJACENCY</code>,
<code class="constant">GL_LINE_STRIP_ADJACENCY</code>
</td>
</tr>
<tr>
<td style="text-align: left; border-right: 2px solid ; ">
<code class="constant">GL_TRIANGLES</code>
</td>
<td style="text-align: left; ">
<code class="constant">GL_TRIANGLES</code>,
<code class="constant">GL_TRIANGLE_STRIP</code>,
<code class="constant">GL_TRIANGLE_FAN</code>,
<code class="constant">GL_TRIANGLES_ADJACENCY</code>,
<code class="constant">GL_TRIANGLE_STRIP_ADJACENCY</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
If a geometry shader is present, the output primitive type from the geometry shader must match those
provided in the following table:
</p>
<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: left; "/>
</colgroup>
<thead>
<tr>
<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>
Transform Feedback <em class="parameter"><code>primitiveMode</code></em>
</strong></span>
</th>
<th style="text-align: left; border-bottom: 2px solid ; ">
<span class="bold"><strong>
Allowed Geometry Shader Output Primitive Type
</strong></span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; "> <code class="constant">GL_POINTS</code> </td>
<td style="text-align: left; border-bottom: 2px solid ; "> <code class="constant">points</code> </td>
</tr>
<tr>
<td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; "> <code class="constant">GL_LINES</code> </td>
<td style="text-align: left; border-bottom: 2px solid ; "> <code class="constant">line_strip</code> </td>
</tr>
<tr>
<td style="text-align: left; border-right: 2px solid ; "> <code class="constant">GL_TRIANGLES</code> </td>
<td style="text-align: left; "> <code class="constant">triangle_strip</code> </td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="refsect1" id="notes">
<h2>Notes</h2>
<p>
Geometry shaders, and the <code class="constant">GL_TRIANGLES_ADJACENCY</code>, <code class="constant">GL_TRIANGLE_STRIP_ADJACENCY</code>,
<code class="constant">GL_LINES_ADJACENCY</code> and <code class="constant">GL_LINE_STRIP_ADJACENCY</code> primtive modes are available
only if the GL version is 3.2 or greater.
</p>
</div>
<div class="refsect1" id="errors">
<h2>Errors</h2>
<p>
<code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glBeginTransformFeedback</code> is executed
while transform feedback is active.
</p>
<p>
<code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glEndTransformFeedback</code> is executed
while transform feedback is not active.
</p>
<p>
<code class="constant">GL_INVALID_OPERATION</code> is generated by <a class="citerefentry" href="glDrawArrays"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a>
if no geometry shader is present, transform feedback is active and <em class="parameter"><code>mode</code></em> is not one of the allowed modes.
</p>
<p>
<code class="constant">GL_INVALID_OPERATION</code> is generated by <a class="citerefentry" href="glDrawArrays"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a>
if a geometry shader is present, transform feedback is active and the output primitive type of the geometry shader does not
match the transform feedback <em class="parameter"><code>primitiveMode</code></em>.
</p>
<p>
<code class="constant">GL_INVALID_OPERATION</code> is generated by <code class="function">glEndTransformFeedback</code> if any binding
point used in transform feedback mode does not have a buffer object bound.
</p>
<p>
<code class="constant">GL_INVALID_OPERATION</code> is generated by <code class="function">glEndTransformFeedback</code> if no binding
points would be used, either because no program object is active of because the active program object has specified
no varying variables to record.
</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; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<col style="text-align: center; "/>
<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="12">
<span class="bold"><strong>OpenGL Version</strong></span>
</th>
</tr>
<tr>
<th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>Function / Feature 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>2.1</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-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>3.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.0</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.1</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.2</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.3</strong></span>
</th>
<th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.4</strong></span>
</th>
<th style="text-align: center; border-bottom: 2px solid ; ">
<span class="bold"><strong>4.5</strong></span>
</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
<code class="function">glBeginTransformFeedback</code>
</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">-</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">✔</td>
<td style="text-align: center; border-bottom: 2px solid ; ">✔</td>
</tr>
<tr>
<td style="text-align: left; border-right: 2px solid ; ">
<code class="function">glEndTransformFeedback</code>
</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; 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>
</div>
<div class="refsect1" id="Copyright">
<h2>Copyright</h2>
<p>
Copyright © 2010-2014 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>