upstream-man-pages/man4/xhtml/glDispatchComputeIndirect.xml

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   4 <?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>glDispatchComputeIndirect - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glDispatchComputeIndirect"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glDispatchComputeIndirect — launch one or more compute work groups using parameters stored in a buffer</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glDispatchComputeIndirect</b>(</code></td><td>GLintptr  </td><td><var class="pdparam">indirect</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>indirect</code></em></span></dt><dd><p>
   5                     The offset into the buffer object currently bound to the
   6                     <code class="constant">GL_DISPATCH_INDIRECT_BUFFER</code> buffer target at
   7                     which the dispatch parameters are stored.
   8                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
   9             <code class="function">glDispatchComputeIndirect</code> launches one or more compute
  10             work groups using parameters stored in the buffer object currently bound
  11             to the <code class="constant">GL_DISPATCH_INDIRECT_BUFFER</code> target.
  12             Each work group is processed by the active program object for the compute
  13             shader stage. While the individual shader invocations within a work group are
  14             executed as a unit, work groups are executed completely independently and in
  15             unspecified order. <em class="parameter"><code>indirect</code></em> contains the offset
  16             into the data store of the buffer object bound to the <code class="constant">GL_DISPATCH_INDIRECT_BUFFER</code>
  17             target at which the parameters are stored.
  18         </p><p>
  19             The parameters addressed by <em class="parameter"><code>indirect</code></em> are packed a structure,
  20             which takes the form (in C):
  21             </p><pre class="programlisting">    typedef  struct {
  22         uint  num_groups_x;
  23         uint  num_groups_y;
  24         uint  num_groups_z;
  25     } DispatchIndirectCommand;</pre><p>
  26         </p><p>
  27             A call to <code class="function">glDispatchComputeIndirect</code> is equivalent, assuming no
  28             errors are generated, to:
  29             </p><pre class="programlisting">    cmd = (const DispatchIndirectCommand  *)indirect;
  30     glDispatchComputeIndirect(cmd-&gt;num_groups_x, cmd-&gt;num_groups_y, cmd-&gt;num_groups_z);
  31     }</pre><p>
  32         </p><p>
  33             Unlike <a href="glDispatchCompute.xml"><span class="citerefentry"><span class="refentrytitle">glDispatchCompute</span></span></a>,
  34             no error is generated if any of the <code class="code">num_groups_x</code>,
  35             <code class="code">num_groups_y</code> or <code class="code">num_groups_z</code> members
  36             of the <code class="code">DispatchIndirectCommand</code> is larger than the
  37             value of <code class="constant">GL_MAX_COMPUTE_WORK_GROUP_COUNT</code> for the
  38             corresponding dimension. In such circumstances, behavior is undefined and
  39             may lead to application termination.
  40         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
  41             <code class="constant">GL_INVALID_OPERATION</code> is generated if there is no active program
  42             for the compute shader stage.
  43         </p><p>
  44             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>indirect</code></em> is
  45             less than zero or not a multiple of four.
  46         </p><p>
  47             <code class="constant">GL_INVALID_OPERATION</code> is generated if no buffer is bound to the
  48             <code class="constant">GL_DISPATCH_INDIRECT_BUFFER</code> target or if the command would
  49             source data beyond the end of the buffer object's data store.
  50         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
  51             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAX_COMPUTE_WORK_GROUP_COUNT</code>
  52         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  53             <a href="glDispatchCompute.xml"><span class="citerefentry"><span class="refentrytitle">glDispatchCompute</span></span></a>.
  54         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  55             Copyright <span class="trademark"></span>© 2012 Khronos Group.
  56             This material may be distributed subject to the terms and conditions set forth in
  57             the Open Publication License, v 1.0, 8 June 1999.
  58             <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
  59         </p></div></div></body></html>