upstream-man-pages/manglsl/gl_SamplePosition.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="gl_SamplePosition">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>gl_SamplePosition</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>gl_SamplePosition</refname>
  17         <refpurpose>contains the location of the current sample within the current fragment</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <function>in vec2 gl_SamplePosition;</function>
  22         </funcsynopsis>
  23     </refsynopsisdiv>
  24     <refsect1 id="description"><title>Description</title>
  25         <para>
  26             <function>gl_SamplePosition</function> is a fragment language input variable that contains
  27             the location within a fragment of the sample currently being processed. The x and y components
  28             of <function>gl_SamplePosition</function> contain the sub-pixel coordinate of the current
  29             sample and will have values in the range 0.0 to 1.0. The sub-pixel coordinates of the center
  30             of the pixel are always (0.5, 0.5). Any static use of <function>gl_SamplePosition</function>
  31             causes the entire fragment shader to be evaluated per-sample rather than per-fragment. When rendering
  32             to a non-multisample buffer, or if multisample rasterization is disabled, <function>gl_SamplePosition</function>
  33             will be (0.5, 0.5).
  34         </para>
  35     </refsect1>
  36     <refsect1 id="versions"><title>Version Support</title>
  37         <informaltable frame="topbot">
  38             <tgroup cols="3" align="left">
  39                 <colspec colwidth="1.1*" />
  40                 <colspec colwidth="1*" align="center" />
  41                 <colspec colwidth="1*" align="center" />
  42                 <colspec colwidth="1*" align="center" />
  43                 <colspec colwidth="1*" align="center" />
  44                 <colspec colwidth="1*" align="center" />
  45                 <colspec colwidth="1*" align="center" />
  46                 <colspec colwidth="1*" align="center" />
  47                 <colspec colwidth="1*" align="center" />
  48                 <thead>
  49                     <row>
  50                         <entry rowsep="1" align="left"><emphasis role="bold">
  51                         Variable
  52                         </emphasis></entry>
  53                         <entry rowsep="1" align="left"><emphasis role="bold">
  54                         Version 1.10
  55                         </emphasis></entry>
  56                         <entry rowsep="1" align="left"><emphasis role="bold">
  57                         Version 1.20
  58                         </emphasis></entry>
  59                         <entry rowsep="1" align="left"><emphasis role="bold">
  60                         Version 1.30
  61                         </emphasis></entry>
  62                         <entry rowsep="1" align="left"><emphasis role="bold">
  63                         Version 1.40
  64                         </emphasis></entry>
  65                         <entry rowsep="1" align="left"><emphasis role="bold">
  66                         Version 1.50
  67                         </emphasis></entry>
  68                         <entry rowsep="1" align="left"><emphasis role="bold">
  69                         Version 3.30
  70                         </emphasis></entry>
  71                         <entry rowsep="1" align="left"><emphasis role="bold">
  72                         Version 4.00
  73                         </emphasis></entry>
  74                         <entry rowsep="1" align="left"><emphasis role="bold">
  75                         Version 4.10
  76                         </emphasis></entry>
  77                     </row>
  78                     <row>
  79                         <entry>
  80                             gl_SamplePosition
  81                         </entry>
  82                         <entry>
  83                             <emphasis>-</emphasis>  <!-- 1.10, OpenGL 2.0 -->
  84                         </entry>
  85                         <entry>
  86                             <emphasis>-</emphasis>  <!-- 1.20, OpenGL 2.1 -->
  87                         </entry>
  88                         <entry>
  89                             <emphasis>-</emphasis>  <!-- 1.30, OpenGL 3.0 -->
  90                         </entry>
  91                         <entry>
  92                             <emphasis>-</emphasis>  <!-- 1.40, OpenGL 3.1 -->
  93                         </entry>
  94                         <entry>
  95                             <emphasis>-</emphasis>  <!-- 1.50, OpenGL 3.2 -->
  96                         </entry>
  97                         <entry>
  98                             <emphasis>-</emphasis>  <!-- 3.30, OpenGL 3.3 -->
  99                         </entry>
 100                         <entry>
 101                             <emphasis>Y</emphasis>  <!-- 4.00, OpenGL 4.0 -->
 102                         </entry>
 103                         <entry>
 104                             <emphasis>Y</emphasis>  <!-- 4.10, OpenGL 4.1 -->
 105                         </entry>
 106                     </row>
 107                 </thead>
 108             </tgroup>
 109         </informaltable>
 110     </refsect1>
 111     <refsect1 id="seealso"><title>See Also</title>
 112         <para>
 113             <citerefentry><refentrytitle>gl_SampleID</refentrytitle></citerefentry>,
 114             <citerefentry><refentrytitle>gl_SampleMask</refentrytitle></citerefentry>,
 115             <citerefentry><refentrytitle>gl_FragCoord</refentrytitle></citerefentry>
 116         </para>
 117     </refsect1>
 118     <refsect1 id="Copyright"><title>Copyright</title>
 119         <para>
 120             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 121             This material may be distributed subject to the terms and conditions set forth in
 122             the Open Publication License, v 1.0, 8 June 1999.
 123             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 124         </para>
 125     </refsect1>
 126 </refentry>