upstream-doc/manglsl/gl_SampleMask.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_SampleMask">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>gl_SampleMask</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>gl_SampleMask</refname>
  17         <refpurpose>specifies the sample coverage mask for the current fragment</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <function>out int gl_SampleMask[];</function>
  22         </funcsynopsis>
  23     </refsynopsisdiv>
  24     <refsect1 id="description"><title>Description</title>
  25         <para>
  26             <function>gl_SampleMask</function> is a fragment language output array that may be
  27             used to set the sample mask for the fragment being processed. Coverage for the current
  28             fragment will become the logical AND of the coverage mask and the output <function>gl_SampleMask</function>.
  29             That is, setting a bit in <function>gl_SampleMask</function> to zero will cause the
  30             corresponding sample to be considered uncovered for the purposes of multisample fragment operations. However,
  31             setting sample mask bits back to one will never enable samples not covered by the original primitive.
  32             Bit <emphasis>B</emphasis> of mask <function>gl_SampleMask[M]</function> corresponds to sample
  33             32 * <emphasis>M</emphasis> + <emphasis>B</emphasis>. This array must be sized in the fragment shader
  34             either implicitly or explicitly to be the same size as the implementation-dependent maximum
  35             sample-mask (as an array of 32-bit elements), determined by the maximum number of samples.
  36             If the fragment shader statically assigns a value to <function>gl_SampleMask</function>, the
  37             sample mask will be undefined for any array elements of any fragment shader invocation that
  38             fails to assign a value. If a shader does not statically assign a value to <function>gl_SampleMask</function>,
  39             the sample mask has no effect on the processing of a fragment.
  40             If the fragment shader is being evaluated at any  frequency other than per-fragment, bits within
  41             the sample mask not corresponding to the current fragment shader invocation are ignored.
  42         </para>
  43     </refsect1>
  44     <refsect1 id="versions"><title>Version Support</title>
  45         <informaltable frame="topbot">
  46             <tgroup cols="10" align="left">
  47                 <colspec colwidth="1.1*" />
  48                 <colspec colwidth="1*" align="center" />
  49                 <colspec colwidth="1*" align="center" />
  50                 <colspec colwidth="1*" align="center" />
  51                 <colspec colwidth="1*" align="center" />
  52                 <colspec colwidth="1*" align="center" />
  53                 <colspec colwidth="1*" align="center" />
  54                 <colspec colwidth="1*" align="center" />
  55                 <colspec colwidth="1*" align="center" />
  56                 <colspec colwidth="1*" align="center" />
  57                 <thead>
  58                     <row>
  59                         <entry rowsep="1" align="left"><emphasis role="bold">
  60                         Variable
  61                         </emphasis></entry>
  62                         <entry rowsep="1" align="left"><emphasis role="bold">
  63                         Version 1.10
  64                         </emphasis></entry>
  65                         <entry rowsep="1" align="left"><emphasis role="bold">
  66                         Version 1.20
  67                         </emphasis></entry>
  68                         <entry rowsep="1" align="left"><emphasis role="bold">
  69                         Version 1.30
  70                         </emphasis></entry>
  71                         <entry rowsep="1" align="left"><emphasis role="bold">
  72                         Version 1.40
  73                         </emphasis></entry>
  74                         <entry rowsep="1" align="left"><emphasis role="bold">
  75                         Version 1.50
  76                         </emphasis></entry>
  77                         <entry rowsep="1" align="left"><emphasis role="bold">
  78                         Version 3.30
  79                         </emphasis></entry>
  80                         <entry rowsep="1" align="left"><emphasis role="bold">
  81                         Version 4.00
  82                         </emphasis></entry>
  83                         <entry rowsep="1" align="left"><emphasis role="bold">
  84                         Version 4.10
  85                         </emphasis></entry>
  86                         <entry rowsep="1" align="left"><emphasis role="bold">
  87                         Version 4.20
  88                         </emphasis></entry>
  89                     </row>
  90                     <row>
  91                         <entry>
  92                             gl_SampleMask
  93                         </entry>
  94                         <entry>
  95                             <emphasis>-</emphasis>  <!-- 1.10, OpenGL 2.0 -->
  96                         </entry>
  97                         <entry>
  98                             <emphasis>-</emphasis>  <!-- 1.20, OpenGL 2.1 -->
  99                         </entry>
 100                         <entry>
 101                             <emphasis>-</emphasis>  <!-- 1.30, OpenGL 3.0 -->
 102                         </entry>
 103                         <entry>
 104                             <emphasis>-</emphasis>  <!-- 1.40, OpenGL 3.1 -->
 105                         </entry>
 106                         <entry>
 107                             <emphasis>-</emphasis>  <!-- 1.50, OpenGL 3.2 -->
 108                         </entry>
 109                         <entry>
 110                             <emphasis>-</emphasis>  <!-- 3.30, OpenGL 3.3 -->
 111                         </entry>
 112                         <entry>
 113                             <emphasis>Y</emphasis>  <!-- 4.00, OpenGL 4.0 -->
 114                         </entry>
 115                         <entry>
 116                             <emphasis>Y</emphasis>  <!-- 4.10, OpenGL 4.1 -->
 117                         </entry>
 118                         <entry>
 119                             <emphasis>Y</emphasis>  <!-- 4.20, OpenGL 4.2 -->
 120                         </entry>
 121                     </row>
 122                 </thead>
 123             </tgroup>
 124         </informaltable>
 125     </refsect1>
 126     <refsect1 id="seealso"><title>See Also</title>
 127         <para>
 128             <citerefentry><refentrytitle>gl_SampleMaskIn</refentrytitle></citerefentry>,
 129             <citerefentry><refentrytitle>gl_SampleID</refentrytitle></citerefentry>,
 130             <citerefentry><refentrytitle>gl_SamplePosition</refentrytitle></citerefentry>,
 131             <citerefentry><refentrytitle>gl_FragCoord</refentrytitle></citerefentry>
 132         </para>
 133     </refsect1>
 134     <refsect1 id="Copyright"><title>Copyright</title>
 135         <para>
 136             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 137             This material may be distributed subject to the terms and conditions set forth in
 138             the Open Publication License, v 1.0, 8 June 1999.
 139             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 140         </para>
 141     </refsect1>
 142 </refentry>