upstream-man-pages/manglsl/texture.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="texture">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>texture</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>texture</refname>
  17         <refpurpose>retrieves texels from a texture</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>gvec4 <function>texture</function></funcdef>
  23                 <paramdef>gsampler1D <parameter>sampler</parameter></paramdef>
  24                 <paramdef>float <parameter>P</parameter></paramdef>
  25                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  26             </funcprototype>
  27             <funcprototype>
  28                 <funcdef>gvec4 <function>texture</function></funcdef>
  29                 <paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
  30                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  31                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  32             </funcprototype>
  33             <funcprototype>
  34                 <funcdef>gvec4 <function>texture</function></funcdef>
  35                 <paramdef>gsampler3D <parameter>sampler</parameter></paramdef>
  36                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  37                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  38             </funcprototype>
  39             <funcprototype>
  40                 <funcdef>gvec4 <function>texture</function></funcdef>
  41                 <paramdef>gsamplerCube <parameter>sampler</parameter></paramdef>
  42                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  43                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  44             </funcprototype>
  45             <funcprototype>
  46                 <funcdef>float <function>texture</function></funcdef>
  47                 <paramdef>sampler1DShadow <parameter>sampler</parameter></paramdef>
  48                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  49                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  50             </funcprototype>
  51             <funcprototype>
  52                 <funcdef>float <function>texture</function></funcdef>
  53                 <paramdef>sampler2DShadow <parameter>sampler</parameter></paramdef>
  54                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  55                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  56             </funcprototype>
  57             <funcprototype>
  58                 <funcdef>float <function>texture</function></funcdef>
  59                 <paramdef>samplerCubeShadow <parameter>sampler</parameter></paramdef>
  60                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  61                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  62             </funcprototype>
  63             <funcprototype>
  64                 <funcdef>gvec4 <function>texture</function></funcdef>
  65                 <paramdef>gsampler1DArray <parameter>sampler</parameter></paramdef>
  66                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  67                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  68             </funcprototype>
  69             <funcprototype>
  70                 <funcdef>gvec4 <function>texture</function></funcdef>
  71                 <paramdef>gsampler2DArray <parameter>sampler</parameter></paramdef>
  72                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  73                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  74             </funcprototype>
  75             <funcprototype>
  76                 <funcdef>gvec4 <function>texture</function></funcdef>
  77                 <paramdef>gsamplerCubeArray <parameter>sampler</parameter></paramdef>
  78                 <paramdef>vec4 <parameter>P</parameter></paramdef>
  79                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  80             </funcprototype>
  81             <funcprototype>
  82                 <funcdef>float <function>texture</function></funcdef>
  83                 <paramdef>sampler1DArrayShadow <parameter>sampler</parameter></paramdef>
  84                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  85                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  86             </funcprototype>
  87             <funcprototype>
  88                 <funcdef>float <function>texture</function></funcdef>
  89                 <paramdef>gsampler2DArrayShadow <parameter>sampler</parameter></paramdef>
  90                 <paramdef>vec4 <parameter>P</parameter></paramdef>
  91                 <paramdef>[float <parameter>bias</parameter>]</paramdef>
  92             </funcprototype>
  93             <funcprototype>
  94                 <funcdef>gvec4 <function>texture</function></funcdef>
  95                 <paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>
  96                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  97             </funcprototype>
  98             <funcprototype>
  99                 <funcdef>float <function>texture</function></funcdef>
 100                 <paramdef>sampler2DRectShadow <parameter>sampler</parameter></paramdef>
 101                 <paramdef>vec3 <parameter>P</parameter></paramdef>
 102             </funcprototype>
 103             <funcprototype>
 104                 <funcdef>float <function>texture</function></funcdef>
 105                 <paramdef>gsamplerCubeArrayShadow <parameter>sampler</parameter></paramdef>
 106                 <paramdef>vec4 <parameter>P</parameter></paramdef>
 107                 <paramdef>float <parameter>compare</parameter></paramdef>
 108             </funcprototype>
 109         </funcsynopsis>
 110     </refsynopsisdiv>
 111     <refsect1 id="parameters"><title>Parameters</title>
 112         <variablelist>
 113         <varlistentry>
 114             <term><parameter>sampler</parameter></term>
 115             <listitem>
 116                 <para>
 117                     Specifies the sampler to which the texture from which texels will be retrieved is bound.
 118                 </para>
 119             </listitem>
 120         </varlistentry>
 121         <varlistentry>
 122             <term><parameter>P</parameter></term>
 123             <listitem>
 124                 <para>
 125                     Specifies the texture coordinates at which texture will be sampled.
 126                 </para>
 127             </listitem>
 128         </varlistentry>
 129         <varlistentry>
 130             <term><parameter>bias</parameter></term>
 131             <listitem>
 132                 <para>
 133                     Specifies an optional bias to be applied during level-of-detail computation.
 134                 </para>
 135             </listitem>
 136         </varlistentry>
 137         <varlistentry>
 138             <term><parameter>compare</parameter></term>
 139             <listitem>
 140                 <para>
 141                     Specifies the value to which the fetched texel will be compared when sampling from <code>gsamplerCubeArrayShadow</code>.
 142                 </para>
 143             </listitem>
 144         </varlistentry>
 145         </variablelist>
 146     </refsect1>
 147     <refsect1 id="description"><title>Description</title>
 148         <para>
 149             <function>texture</function> samples texels from the texture bound to <parameter>sampler</parameter> at texture
 150             coordinate <parameter>P</parameter>. An optional bias, specified in <parameter>bias</parameter> is included in
 151             the level-of-detail computation that is used to choose mipmap(s) from which to sample.
 152         </para>
 153         <para>
 154             For <emphasis>shadow</emphasis> forms, when <parameter>compare</parameter> is present, it is used as
 155             <inlineequation><mml:math><mml:msub><mml:mi>D</mml:mi><mml:mi>sub</mml:mi></mml:msub></mml:math></inlineequation>
 156             and the array layer is specified in <code><parameter>P</parameter>.w</code>. When <parameter>compare</parameter> is
 157             not present, the last component of <parameter>P</parameter> is used as
 158             <inlineequation><mml:math><mml:msub><mml:mi>D</mml:mi><mml:mi>sub</mml:mi></mml:msub></mml:math></inlineequation> and the
 159             array layer is specified in the second to last component of <parameter>P</parameter>. (The second component of <parameter>P</parameter>
 160             is unused for <emphasis>1D</emphasis> shadow lookups.)
 161         </para>
 162         <para>
 163             For non-shadow variants, the array layer comes from the last component of <parameter>P</parameter>.
 164         </para>
 165     </refsect1>
 166     <refsect1 id="versions"><title>Version Support</title>
 167         <informaltable frame="topbot">
 168             #VARTABLECOLS#
 169                 <thead>
 170                     #FUNCTABLEHEADER#
 171                     <row>
 172                         <entry>texture</entry>#newin13#
 173                     </row>
 174                     <row>
 175                         <entry>texture (gsampler2DRect{Shadow})</entry>#newin14#
 176                     </row>
 177                     <row>
 178                         <entry>texture (gsampler2DMS, gsampler2DMSArray)</entry>#newin15#
 179                     </row>
 180                     <row>
 181                         <entry>texture (gsamplerCubeArray{Shadow})</entry>#newin40#
 182                     </row>
 183                 </thead>
 184             </tgroup>
 185         </informaltable>
 186     </refsect1>
 187     <refsect1 id="seealso"><title>See Also</title>
 188         <para>
 189             <citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,
 190             <citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,
 191             <citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry>,
 192             <citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
 193             <citerefentry><refentrytitle>textureGatherOffsets</refentrytitle></citerefentry>,
 194             <citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,
 195             <citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,
 196             <citerefentry><refentrytitle>textureLod</refentrytitle></citerefentry>,
 197             <citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,
 198             <citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,
 199             <citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,
 200             <citerefentry><refentrytitle>textureProjGrad</refentrytitle></citerefentry>,
 201             <citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,
 202             <citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,
 203             <citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,
 204             <citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,
 205             <citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,
 206             <citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>
 207         </para>
 208     </refsect1>
 209     <refsect1 id="Copyright"><title>Copyright</title>
 210         <para>
 211             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 212             This material may be distributed subject to the terms and conditions set forth in
 213             the Open Publication License, v 1.0, 8 June 1999.
 214             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 215         </para>
 216     </refsect1>
 217 </refentry>