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"opengl-man.css" /><title>barrier - OpenGL Shading Language (GLSL)
</title><meta name=
"generator" content=
"DocBook XSL Stylesheets V1.69.1" /></head><body><div class=
"refentry" lang=
"en" xml:
lang=
"en"><a id=
"barrier"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>barrier — synchronize execution of multiple shader invocations
</p></div><div class=
"refsynopsisdiv"><h2>Declaration
</h2><div class=
"funcsynopsis"><p><code class=
"funcdef">void
<b class=
"fsfunc">barrier
</b>(
</code>void
<code>)
</code>;
</p></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
5 <span class=
"emphasis"><em>Available only in the Tessellation Control and Compute Shaders
</em></span>,
<code class=
"function">barrier
</code> provides
6 a partially defined order of execution between shader invocations. For any given static instance of
<code class=
"function">barrier
</code>,
7 in a tessellation control shader, all invocations for a single input patch must enter it before any will be allowed
8 to continue beyond it. For any given static instance of
<code class=
"function">barrier
</code> in a compute shader, all invocations
9 within a single work group must enter it before any are allowed to continue beyond it.
10 This ensures that values written by one invocation prior to a given static instance
11 of
<code class=
"function">barrier
</code> can be safely read by other invocations after their call to the same static
12 instance of
<code class=
"function">barrier
</code>. Because invocations may execute in undefined order between these
13 <code class=
"function">barrier
</code> calls, the values of a per-vertex or per-patch output variable, or any shared variable will be undefined
16 <code class=
"function">barrier
</code> may only be placed inside the function
<code class=
"code">main()
</code> of the tessellation
17 control shader, but may be placed anywhere in a compute shader. Calls to
<code class=
"function">barrier
</code> may not
18 be placed within any control flow. Barriers are also disallowed after a return
19 statement in the function
<code class=
"code">main()
</code>.
20 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"versions"></a><h2>Version Support
</h2><div class=
"informaltable"><table border=
"1"><colgroup><col align=
"left" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /></colgroup><thead><tr><th align=
"left"><span class=
"bold"><strong>Function
</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.10</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.20</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.30</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.40</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.50</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
3.30</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.00</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.10</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.20</strong></span></th><th align=
"center"><span class=
"bold"><strong>Version
4.30</strong></span></th></tr><tr><th align=
"left">barrier
</th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th></tr></thead></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
21 Copyright
<span class=
"trademark"></span>©
2011-
2012 Khronos Group.
22 This material may be distributed subject to the terms and conditions set forth in
23 the Open Publication License, v
1.0,
8 June
1999.
24 <a href=
"http://opencontent.org/openpub/" target=
"_top">http://opencontent.org/openpub/
</a>.
25 </p></div></div></body></html>