<div class="refentry"><a id="glDrawElementsInstanced"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glDrawElementsInstanced — draw multiple instances of a set of elements</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glDrawElementsInstanced</strong>(</code></td><td>GLenum <var class="pdparam">mode</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">count</var>, </td></tr><tr><td> </td><td>GLenum <var class="pdparam">type</var>, </td></tr><tr><td> </td><td>const void * <var class="pdparam">indices</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">primcount</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>mode</code></em></span></dt><dd><p>

Specifies what kind of primitives to render.

Symbolic constants

<code class="constant">GL_POINTS</code>,

<code class="constant">GL_LINE_STRIP</code>,

<code class="constant">GL_LINE_LOOP</code>,

<code class="constant">GL_LINES</code>,

<code class="constant">GL_LINE_STRIP_ADJACENCY</code>,

<code class="constant">GL_LINES_ADJACENCY</code>,

<code class="constant">GL_TRIANGLE_STRIP</code>,

<code class="constant">GL_TRIANGLE_FAN</code>,

<code class="constant">GL_TRIANGLES</code>,

<code class="constant">GL_TRIANGLE_STRIP_ADJACENCY</code> and

<code class="constant">GL_TRIANGLES_ADJACENCY</code>

are accepted.

</p></dd><dt><span class="term"><em class="parameter"><code>count</code></em></span></dt><dd><p>

Specifies the number of elements to be rendered.

</p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>

Specifies the type of the values in <em class="parameter"><code>indices</code></em>. Must be one of <code class="constant">GL_UNSIGNED_BYTE</code>,

<code class="constant">GL_UNSIGNED_SHORT</code>, or <code class="constant">GL_UNSIGNED_INT</code>.

</p></dd><dt><span class="term"><em class="parameter"><code>indices</code></em></span></dt><dd><p>

Specifies a pointer to the location where the indices are stored.

</p></dd><dt><span class="term"><em class="parameter"><code>primcount</code></em></span></dt><dd><p>

Specifies the number of instances of the specified range of indices to be rendered.

</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p>

<code class="function">glDrawElementsInstanced</code> behaves identically to <a class="citerefentry" href="glDrawElements"><span class="citerefentry"><span class="refentrytitle">glDrawElements</span></span></a>

except that <em class="parameter"><code>primcount</code></em> instances of the set of elements are executed and the value of the internal counter

<em class="parameter"><code>instanceID</code></em> advances for each iteration. <em class="parameter"><code>instanceID</code></em> is an internal 32-bit integer counter

that may be read by a vertex shader as <code class="constant">gl_InstanceID</code>.

</p><p>

<code class="function">glDrawElementsInstanced</code> has the same effect as:

</p><pre class="programlisting"> if (mode, count, or type is invalid )

generate appropriate error

else {

for (int i = 0; i &lt; primcount ; i++) {

instanceID = i;

glDrawElements(mode, count, type, indices);

}

instanceID = 0;

}</pre><p>

</p></div><div class="refsect1"><a id="notes"></a><h2>Notes</h2><p>

<code class="function">glDrawElementsInstanced</code> is available only if the GL version is 3.1 or greater.

</p><p>

<code class="constant">GL_LINE_STRIP_ADJACENCY</code>,

<code class="constant">GL_LINES_ADJACENCY</code>,

<code class="constant">GL_TRIANGLE_STRIP_ADJACENCY</code> and

<code class="constant">GL_TRIANGLES_ADJACENCY</code>

are available only if the GL version is 3.2 or greater.

</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p>

<code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>mode</code></em> is not one of <code class="constant">GL_POINTS</code>,

<code class="constant">GL_LINE_STRIP</code>, <code class="constant">GL_LINE_LOOP</code>, <code class="constant">GL_LINES</code>,

<code class="constant">GL_TRIANGLE_STRIP</code>, <code class="constant">GL_TRIANGLE_FAN</code>, or <code class="constant">GL_TRIANGLES</code>.

</p><p>

<code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>count</code></em> or <em class="parameter"><code>primcount</code></em> are negative.

</p><p>

<code class="constant">GL_INVALID_OPERATION</code> is generated if a geometry shader is active and <em class="parameter"><code>mode</code></em>

is incompatible with the input primitive type of the geometry shader in the currently installed program object.

</p><p>

<code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to an

enabled array and the buffer object's data store is currently mapped.

</p></div>

{$pipelinestall}{$examples}

<div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p>

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

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

</p></div><div class="refsect1"><div id="Copyright"><h2>Copyright</h2><p>

Copyright © 2010 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="ulink" href="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.

</p></div></div></div>