upstream-man-pages/manglsl/textureGather.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="textureGather">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>textureGather</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>textureGather</refname>
  17         <refpurpose>gathers four texels from a texture</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>gvec4 <function>textureGather</function></funcdef>
  23                 <paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
  24                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  25                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  26             </funcprototype>
  27             <funcprototype>
  28                 <funcdef>gvec4 <function>textureGather</function></funcdef>
  29                 <paramdef>gsampler2DArray <parameter>sampler</parameter></paramdef>
  30                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  31                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  32             </funcprototype>
  33             <funcprototype>
  34                 <funcdef>gvec4 <function>textureGather</function></funcdef>
  35                 <paramdef>gsamplerCube <parameter>sampler</parameter></paramdef>
  36                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  37                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  38             </funcprototype>
  39             <funcprototype>
  40                 <funcdef>gvec4 <function>textureGather</function></funcdef>
  41                 <paramdef>gsamplerCubeArray <parameter>sampler</parameter></paramdef>
  42                 <paramdef>vec4 <parameter>P</parameter></paramdef>
  43                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  44             </funcprototype>
  45             <funcprototype>
  46                 <funcdef>gvec4 <function>textureGather</function></funcdef>
  47                 <paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>
  48                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  49                 <paramdef>[int <parameter>comp]</parameter></paramdef>
  50             </funcprototype>
  51             <funcprototype>
  52                 <funcdef>vec4 <function>textureGather</function></funcdef>
  53                 <paramdef>gsampler2DShadow <parameter>sampler</parameter></paramdef>
  54                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  55                 <paramdef>float <parameter>refZ</parameter></paramdef>
  56             </funcprototype>
  57             <funcprototype>
  58                 <funcdef>vec4 <function>textureGather</function></funcdef>
  59                 <paramdef>gsampler2DArrayShadow <parameter>sampler</parameter></paramdef>
  60                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  61                 <paramdef>float <parameter>refZ</parameter></paramdef>
  62             </funcprototype>
  63             <funcprototype>
  64                 <funcdef>vec4 <function>textureGather</function></funcdef>
  65                 <paramdef>gsamplerCubeShadow <parameter>sampler</parameter></paramdef>
  66                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  67                 <paramdef>float <parameter>refZ</parameter></paramdef>
  68             </funcprototype>
  69             <funcprototype>
  70                 <funcdef>vec4 <function>textureGather</function></funcdef>
  71                 <paramdef>gsamplerCubeArrayShadow <parameter>sampler</parameter></paramdef>
  72                 <paramdef>vec4 <parameter>P</parameter></paramdef>
  73                 <paramdef>float <parameter>refZ</parameter></paramdef>
  74             </funcprototype>
  75             <funcprototype>
  76                 <funcdef>vec4 <function>textureGather</function></funcdef>
  77                 <paramdef>gsampler2DRectShadow <parameter>sampler</parameter></paramdef>
  78                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  79                 <paramdef>float <parameter>refZ</parameter></paramdef>
  80             </funcprototype>
  81         </funcsynopsis>
  82     </refsynopsisdiv>
  83     <refsect1 id="parameters"><title>Parameters</title>
  84         <variablelist>
  85         <varlistentry>
  86             <term><parameter>sampler</parameter></term>
  87             <listitem>
  88                 <para>
  89                     Specifies the sampler to which the texture from which texels will be retrieved is bound.
  90                 </para>
  91             </listitem>
  92         </varlistentry>
  93         <varlistentry>
  94             <term><parameter>P</parameter></term>
  95             <listitem>
  96                 <para>
  97                     Specifies the texture coordinates at which texture will be sampled.
  98                 </para>
  99             </listitem>
 100         </varlistentry>
 101         <varlistentry>
 102             <term><parameter>comp</parameter></term>
 103             <listitem>
 104                 <para>
 105                     Specifies the component of the source texture that will be used to generate the resulting vector.
 106                 </para>
 107             </listitem>
 108         </varlistentry>
 109         <varlistentry>
 110             <term><parameter>refZ</parameter></term>
 111             <listitem>
 112                 <para>
 113                     Specifies the reference Z value used in the comparison for shadow forms.
 114                 </para>
 115             </listitem>
 116         </varlistentry>
 117         </variablelist>
 118     </refsect1>
 119     <refsect1 id="description"><title>Description</title>
 120         <para>
 121             <function>textureGather</function> returns the value:
 122         </para>
 123         <para>
 124 <programlisting><![CDATA[    vec4(Sample_i0_j1(P, base).comp,
 125          Sample_i1_j1(P, base).comp,
 126          Sample_i1_j0(P, base).comp,
 127          Sample_i0_j9(P, base).comp);]]></programlisting>
 128     </para>
 129     <para>
 130         If specified, the value of <parameter>comp</parameter> must ba constant integer expression with a value
 131         of 0, 1, 2, or 3, identifying the x, y, z or w component of the four-component vector lookup result for each
 132         texel, respectively. If <parameter>comp</parameter> is not specified, it is treated as 0, selecting the x
 133         component of each texel to generate the result.
 134     </para>
 135     </refsect1>
 136     <refsect1 id="versions"><title>Version Support</title>
 137         <informaltable frame="topbot">
 138             #VARTABLECOLS#
 139                 <thead>
 140                     #FUNCTABLEHEADER#
 141                     <row>
 142                         <entry>textureGather</entry>#newin40#
 143                     </row>
 144                 </thead>
 145             </tgroup>
 146         </informaltable>
 147     </refsect1>
 148     <refsect1 id="seealso"><title>See Also</title>
 149         <para>
 150             <citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,
 151             <citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,
 152             <citerefentry><refentrytitle>texture</refentrytitle></citerefentry>,
 153             <citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
 154             <citerefentry><refentrytitle>textureGatherOffsets</refentrytitle></citerefentry>,
 155             <citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,
 156             <citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,
 157             <citerefentry><refentrytitle>textureLod</refentrytitle></citerefentry>,
 158             <citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,
 159             <citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,
 160             <citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,
 161             <citerefentry><refentrytitle>textureProjGrad</refentrytitle></citerefentry>,
 162             <citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,
 163             <citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,
 164             <citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,
 165             <citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,
 166             <citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,
 167             <citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>
 168         </para>
 169     </refsect1>
 170     <refsect1 id="Copyright"><title>Copyright</title>
 171         <para>
 172             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 173             This material may be distributed subject to the terms and conditions set forth in
 174             the Open Publication License, v 1.0, 8 June 1999.
 175             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 176         </para>
 177     </refsect1>
 178 </refentry>