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<?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>gl_SamplePosition - 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="gl_SamplePosition"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>gl_SamplePosition — contains the location of the current sample within the current fragment</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><div class="funcsynopsis"><code class="function">in vec2 gl_SamplePosition;</code></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            <code class="function">gl_SamplePosition</code> is a fragment language input variable that contains
            the location within a fragment of the sample currently being processed. The x and y components
            of <code class="function">gl_SamplePosition</code> contain the sub-pixel coordinate of the current
            sample and will have values in the range 0.0 to 1.0. The sub-pixel coordinates of the center
            of the pixel are always (0.5, 0.5). Any static use of <code class="function">gl_SamplePosition</code>
            causes the entire fragment shader to be evaluated per-sample rather than per-fragment. When rendering
            to a non-multisample buffer, or if multisample rasterization is disabled, <code class="function">gl_SamplePosition</code>
            will be (0.5, 0.5).
        </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" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
                        Variable
                        </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></tr><tr><th align="left">
                            gl_SamplePosition
                        </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></tr></thead></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a href="gl_SampleID.xml"><span class="citerefentry"><span class="refentrytitle">gl_SampleID</span></span></a>,
            <a href="gl_SampleMask.xml"><span class="citerefentry"><span class="refentrytitle">gl_SampleMask</span></span></a>,
            <a href="gl_FragCoord.xml"><span class="citerefentry"><span class="refentrytitle">gl_FragCoord</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 2011 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 href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p></div></div></body></html>
