upstream-man-pages/manglsl/gl_SampleID.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_SampleID">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>gl_SampleID</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>gl_SampleID</refname>
  17         <refpurpose>contains the index of the sample currently being processed</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <function>in int gl_SampleID;</function>
  22         </funcsynopsis>
  23     </refsynopsisdiv>
  24     <refsect1 id="description"><title>Description</title>
  25         <para>
  26             <function>gl_SampleID</function> is a fragment language input variable that contains
  27             the index of the sample currently being processed. This variable is in the range
  28             0 to <citerefentry><refentrytitle>gl_NumSamples</refentrytitle></citerefentry> - 1, where
  29             <citerefentry><refentrytitle>gl_NumSamples</refentrytitle></citerefentry>
  30             is the total number of samples in each fragment for the current framebuffer (and thus 1 if
  31             rendering to a non-multisample buffer). Any static use of this variable in a fragment
  32             shader causes the entire shader to be evaluated per-sample rather than per-fragment.
  33         </para>
  34         <para>
  35             When rendering to a non-multisample buffer, or if multisample rasterization is disabled,
  36             <function>gl_SampleID</function> will always be zero. <citerefentry><refentrytitle>gl_NumSamples</refentrytitle></citerefentry>
  37             is the sample count of the framebuffer regardless of whether multisample rasterization is
  38             enabled or not.
  39         </para>
  40     </refsect1>
  41     <refsect1 id="versions"><title>Version Support</title>
  42         <informaltable frame="topbot">
  43             #VARTABLECOLS#
  44                 <thead>
  45                     #VARTABLEHEADER#
  46                     <row>
  47                         <entry>gl_SampleID</entry>#newin40#
  48                     </row>
  49                 </thead>
  50             </tgroup>
  51         </informaltable>
  52     </refsect1>
  53     <refsect1 id="seealso"><title>See Also</title>
  54         <para>
  55             <citerefentry><refentrytitle>gl_SamplePosition</refentrytitle></citerefentry>,
  56             <citerefentry><refentrytitle>gl_NumSamples</refentrytitle></citerefentry>
  57         </para>
  58     </refsect1>
  59     <refsect1 id="Copyright"><title>Copyright</title>
  60         <para>
  61             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
  62             This material may be distributed subject to the terms and conditions set forth in
  63             the Open Publication License, v 1.0, 8 June 1999.
  64             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
  65         </para>
  66     </refsect1>
  67 </refentry>