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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glMultiDrawArraysIndirect - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1" /></head><body><div class="refentry"><a id="glMultiDrawArraysIndirect"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glMultiDrawArraysIndirect — render multiple sets of primitives from array data, taking parameters from memory</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glMultiDrawArraysIndirect</strong>(</code></td><td>GLenum <var class="pdparam">mode</var>, </td></tr><tr><td> </td><td>const void *<var class="pdparam">indirect</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">drawcount</var>, </td></tr><tr><td> </td><td>GLsizei <var class="pdparam">stride</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>,
<code class="constant">GL_TRIANGLES_ADJACENCY</code>, and
<code class="constant">GL_PATCHES</code>
are accepted.
</p></dd><dt><span class="term"><em class="parameter"><code>indirect</code></em></span></dt><dd><p>
Specifies the address of an array of structures containing the draw parameters.
</p></dd><dt><span class="term"><em class="parameter"><code>drawcount</code></em></span></dt><dd><p>
Specifies the the number of elements in the array of draw parameter structures.
</p></dd><dt><span class="term"><em class="parameter"><code>stride</code></em></span></dt><dd><p>
Specifies the distance in basic machine units between elements of the draw parameter array.
</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p>
<code class="function">glMultiDrawArraysIndirect</code> specifies multiple geometric primitives
with very few subroutine calls. <code class="function">glMultiDrawArraysIndirect</code> behaves
similarly to a multitude of calls to <a class="citerefentry" href="glDrawArraysInstancedBaseInstance.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArraysInstancedBaseInstance</span></span></a>,
execept that the parameters to each call to <a class="citerefentry" href="glDrawArraysInstancedBaseInstance.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArraysInstancedBaseInstance</span></span></a>
are stored in an array in memory at the address given by <em class="parameter"><code>indirect</code></em>, separated
by the stride, in basic machine units, specified by <em class="parameter"><code>stride</code></em>. If <em class="parameter"><code>stride</code></em>
is zero, then the array is assumed to be tightly packed in memory.
</p><p>
The parameters addressed by <em class="parameter"><code>indirect</code></em> are packed into an array of structures,
each element of which takes the form (in C):
</p><pre class="programlisting"> typedef struct {
uint count;
uint instanceCount;
uint first;
uint baseInstance;
} DrawArraysIndirectCommand;</pre><p>
</p><p>
A single call to <code class="function">glMultiDrawArraysIndirect</code> is equivalent, assuming no errors
are generated to:
</p><pre class="programlisting"> GLsizei n;
for (n = 0; n < drawcount; n++) {
const DrawArraysIndirectCommand *cmd;
if (stride != 0) {
cmd = (const DrawArraysIndirectCommand *)((uintptr)indirect + n * stride);
} else {
cmd = (const DrawArraysIndirectCommand *)indirect + n;
}
glDrawArraysInstancedBaseInstance(mode, cmd->first, cmd->count, cmd->instanceCount, cmd->baseInstance);
}</pre><p>
</p><p>
If a buffer is bound to the <code class="constant">GL_DRAW_INDIRECT_BUFFER</code> binding at the time
of a call to <code class="function">glMultiDrawArraysIndirect</code>, <em class="parameter"><code>indirect</code></em>
is interpreted as an offset, in basic machine units, into that buffer and the parameter
data is read from the buffer rather than from client memory.
</p><p>
In contrast to <a class="citerefentry" href="glDrawArraysInstancedBaseInstance.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArraysInstancedBaseInstance</span></span></a>,
the <code class="code">first</code> member of the parameter structure is unsigned, and out-of-range indices
do not generate an error.
</p><p>
Vertex attributes that are modified by <code class="function">glMultiDrawArraysIndirect</code> have an
unspecified value after <code class="function">glMultiDrawArraysIndirect</code> returns. Attributes that aren't
modified remain well defined.
</p></div><div class="refsect1"><a id="notes"></a><h2>Notes</h2><p>
The <em class="parameter"><code>baseInstance</code></em> member of the <em class="parameter"><code>DrawArraysIndirectCommand</code></em>
structure is defined only if the GL version is 4.2 or greater. For versions of the GL less than 4.2,
this parameter is present but is reserved and should be set to zero. On earlier versions of the GL,
behavior is undefined if it is non-zero.
</p><p>
<code class="function">glMultiDrawArraysIndirect</code> is available only if the GL version is 4.3 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 an accepted value.
</p><p>
<code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>stride</code></em> is not a multiple
of four.
</p><p>
<code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>drawcount</code></em> is negative.
</p><p>
<code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to an
enabled array or to the <code class="constant">GL_DRAW_INDIRECT_BUFFER</code> binding and the buffer object's data store is currently mapped.
</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 <em class="parameter"><code>mode</code></em> is <code class="constant">GL_PATCHES</code>
and no tessellation control shader is active.
</p></div><div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p>
<a class="citerefentry" href="glDrawArrays.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArrays</span></span></a>,
<a class="citerefentry" href="glDrawArraysInstanced.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArraysInstanced</span></span></a>,
<a class="citerefentry" href="glDrawElements.xml"><span class="citerefentry"><span class="refentrytitle">glDrawElements</span></span></a>,
<a class="citerefentry" href="glDrawRangeElements.xml"><span class="citerefentry"><span class="refentrytitle">glDrawRangeElements</span></span></a>,
<a class="citerefentry" href="glDrawArraysIndirect.xml"><span class="citerefentry"><span class="refentrytitle">glDrawArraysIndirect</span></span></a>,
<a class="citerefentry" href="glMultiDrawElementsIndirect.xml"><span class="citerefentry"><span class="refentrytitle">glMultiDrawElementsIndirect</span></span></a>
</p></div><div class="refsect1"><a id="Copyright"></a><h2>Copyright</h2><p>
Copyright <span class="trademark"></span>© 2012-2013 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="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
</p></div></div></body></html>
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