upstream-man-pages/manglsl/textureGatherOffsets.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="textureGatherOffsets">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>textureGatherOffsets</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>textureGatherOffsets</refname>
  17         <refpurpose>gathers four texels from a texture with an array of offsets</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>gvec4 <function>textureGatherOffsets</function></funcdef>
  23                 <paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
  24                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  25                 <paramdef>ivec2 <parameter>offsets[4]</parameter></paramdef>
  26                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  27             </funcprototype>
  28             <funcprototype>
  29                 <funcdef>gvec4 <function>textureGatherOffsets</function></funcdef>
  30                 <paramdef>gsampler2DArray <parameter>sampler</parameter></paramdef>
  31                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  32                 <paramdef>ivec2 <parameter>offsets[4]</parameter></paramdef>
  33                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  34             </funcprototype>
  35             <funcprototype>
  36                 <funcdef>gvec4 <function>textureGatherOffsets</function></funcdef>
  37                 <paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>
  38                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  39                 <paramdef>ivec2 <parameter>offsets[4]</parameter></paramdef>
  40                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  41             </funcprototype>
  42             <funcprototype>
  43                 <funcdef>vec4 <function>textureGatherOffsets</function></funcdef>
  44                 <paramdef>gsampler2DShadow <parameter>sampler</parameter></paramdef>
  45                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  46                 <paramdef>float <parameter>refZ</parameter></paramdef>
  47                 <paramdef>ivec2 <parameter>offsets[4]</parameter></paramdef>
  48             </funcprototype>
  49             <funcprototype>
  50                 <funcdef>vec4 <function>textureGatherOffsets</function></funcdef>
  51                 <paramdef>gsampler2DArrayShadow <parameter>sampler</parameter></paramdef>
  52                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  53                 <paramdef>float <parameter>refZ</parameter></paramdef>
  54                 <paramdef>ivec2 <parameter>offsets[4]</parameter></paramdef>
  55             </funcprototype>
  56             <funcprototype>
  57                 <funcdef>vec4 <function>textureGatherOffsets</function></funcdef>
  58                 <paramdef>gsampler2DRectShadow <parameter>sampler</parameter></paramdef>
  59                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  60                 <paramdef>float <parameter>refZ</parameter></paramdef>
  61                 <paramdef>ivec2 <parameter>offsets[4]</parameter></paramdef>
  62             </funcprototype>
  63         </funcsynopsis>
  64     </refsynopsisdiv>
  65     <refsect1 id="parameters"><title>Parameters</title>
  66         <variablelist>
  67         <varlistentry>
  68             <term><parameter>sampler</parameter></term>
  69             <listitem>
  70                 <para>
  71                     Specifies the sampler to which the texture from which texels will be retrieved is bound.
  72                 </para>
  73             </listitem>
  74         </varlistentry>
  75         <varlistentry>
  76             <term><parameter>P</parameter></term>
  77             <listitem>
  78                 <para>
  79                     Specifies the texture coordinates at which texture will be sampled.
  80                 </para>
  81             </listitem>
  82         </varlistentry>
  83         <varlistentry>
  84             <term><parameter>comp</parameter></term>
  85             <listitem>
  86                 <para>
  87                     Specifies the component of the source texture that will be used to generate the resulting vector.
  88                 </para>
  89             </listitem>
  90         </varlistentry>
  91         <varlistentry>
  92             <term><parameter>refZ</parameter></term>
  93             <listitem>
  94                 <para>
  95                     Specifies the reference Z value used in the comparison for shadow forms.
  96                 </para>
  97             </listitem>
  98         </varlistentry>
  99         <varlistentry>
 100             <term><parameter>offsets</parameter></term>
 101             <listitem>
 102                 <para>
 103                     Specifies an array of offsets from the specified texture coordinate <parameter>P</parameter> from which the texels will be gathered.
 104                 </para>
 105             </listitem>
 106         </varlistentry>
 107         </variablelist>
 108     </refsect1>
 109     <refsect1 id="description"><title>Description</title>
 110         <para>
 111             <function>textureGatherOffsets</function> operates identically to <citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
 112             except that <parameter>offsets</parameter> is used to determine the location of the four texels to sample. Each of the four texels is obtained
 113             by applying the offset in <parameter>offsets</parameter> as a (u, v) coordinate offset to <parameter>P</parameter>, identifying the four-texel
 114             <constant>GL_LINEAR</constant> footprint, and then selecting the texel
 115             <inlineequation><mml:math><mml:msub><mml:mi>i</mml:mi><mml:mn>0</mml:mn></mml:msub><mml:msub><mml:mi>i</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math></inlineequation>
 116             of that footprint. The specified values in <parameter>offsets</parameter> must be set with constant integral expressions.
 117         </para>
 118     </refsect1>
 119     <refsect1 id="versions"><title>Version Support</title>
 120         <informaltable frame="topbot">
 121             #VARTABLECOLS#
 122                 <thead>
 123                     #FUNCTABLEHEADER#
 124                     <row>
 125                         <entry>textureGatherOffsets</entry>#newin40#
 126                     </row>
 127                 </thead>
 128             </tgroup>
 129         </informaltable>
 130     </refsect1>
 131     <refsect1 id="seealso"><title>See Also</title>
 132         <para>
 133             <citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,
 134             <citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,
 135             <citerefentry><refentrytitle>texture</refentrytitle></citerefentry>,
 136             <citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry>,
 137             <citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
 138             <citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,
 139             <citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,
 140             <citerefentry><refentrytitle>textureLod</refentrytitle></citerefentry>,
 141             <citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,
 142             <citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,
 143             <citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,
 144             <citerefentry><refentrytitle>textureProjGrad</refentrytitle></citerefentry>,
 145             <citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,
 146             <citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,
 147             <citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,
 148             <citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,
 149             <citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,
 150             <citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>
 151         </para>
 152     </refsect1>
 153     <refsect1 id="Copyright"><title>Copyright</title>
 154         <para>
 155             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 156             This material may be distributed subject to the terms and conditions set forth in
 157             the Open Publication License, v 1.0, 8 June 1999.
 158             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 159         </para>
 160     </refsect1>
 161 </refentry>