upstream-man-pages/manglsl/textureLod.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="textureLod">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>textureLod</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>textureLod</refname>
  17         <refpurpose>perform a texture lookup with explicit level-of-detail</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  23                 <paramdef>gsampler1D <parameter>sampler</parameter></paramdef>
  24                 <paramdef>float <parameter>P</parameter></paramdef>
  25                 <paramdef>float <parameter>lod</parameter></paramdef>
  26             </funcprototype>
  27             <funcprototype>
  28                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  29                 <paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
  30                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  31                 <paramdef>float <parameter>lod</parameter></paramdef>
  32             </funcprototype>
  33             <funcprototype>
  34                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  35                 <paramdef>gsampler3D <parameter>sampler</parameter></paramdef>
  36                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  37                 <paramdef>float <parameter>lod</parameter></paramdef>
  38             </funcprototype>
  39             <funcprototype>
  40                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  41                 <paramdef>gsamplerCube <parameter>sampler</parameter></paramdef>
  42                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  43                 <paramdef>float <parameter>lod</parameter></paramdef>
  44             </funcprototype>
  45             <funcprototype>
  46                 <funcdef>float <function>textureLod</function></funcdef>
  47                 <paramdef>sampler1DShadow <parameter>sampler</parameter></paramdef>
  48                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  49                 <paramdef>float <parameter>lod</parameter></paramdef>
  50             </funcprototype>
  51             <funcprototype>
  52                 <funcdef>float <function>textureLod</function></funcdef>
  53                 <paramdef>sampler2DShadow <parameter>sampler</parameter></paramdef>
  54                 <paramdef>vec4 <parameter>P</parameter></paramdef>
  55                 <paramdef>float <parameter>lod</parameter></paramdef>
  56             </funcprototype>
  57             <funcprototype>
  58                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  59                 <paramdef>gsampler1DArray <parameter>sampler</parameter></paramdef>
  60                 <paramdef>vec2 <parameter>P</parameter></paramdef>
  61                 <paramdef>float <parameter>lod</parameter></paramdef>
  62             </funcprototype>
  63             <funcprototype>
  64                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  65                 <paramdef>gsampler2DArray <parameter>sampler</parameter></paramdef>
  66                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  67                 <paramdef>float <parameter>lod</parameter></paramdef>
  68             </funcprototype>
  69             <funcprototype>
  70                 <funcdef>float <function>textureLod</function></funcdef>
  71                 <paramdef>sampler1DArrayShadow <parameter>sampler</parameter></paramdef>
  72                 <paramdef>vec3 <parameter>P</parameter></paramdef>
  73                 <paramdef>float <parameter>lod</parameter></paramdef>
  74             </funcprototype>
  75             <funcprototype>
  76                 <funcdef>gvec4 <function>textureLod</function></funcdef>
  77                 <paramdef>gsamplerCubeArray <parameter>sampler</parameter></paramdef>
  78                 <paramdef>vec4 <parameter>P</parameter></paramdef>
  79                 <paramdef>float <parameter>lod</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>lod</parameter></term>
 103             <listitem>
 104                 <para>
 105                     Specifies the explicit level-of-detail
 106                 </para>
 107             </listitem>
 108         </varlistentry>
 109         </variablelist>
 110     </refsect1>
 111     <refsect1 id="description"><title>Description</title>
 112         <para>
 113             <function>textureLod</function> performs a texture lookup at coordinate <parameter>P</parameter> from the
 114             texture bound to <parameter>sampler</parameter> with an explicit level-of-detail as specified in <parameter>lod</parameter>.
 115             <parameter>lod</parameter> specifies
 116             <inlineequation><mml:math><mml:msub><mml:mi>&lambda;</mml:mi><mml:mi>base</mml:mi></mml:msub></mml:math></inlineequation>
 117             and sets the partial derivatives as follows:
 118         </para>
 119         <para>
 120             <inlineequation><mml:math>
 121                 <mml:mtable rowalign='center'>
 122                   <mml:mtr>
 123                     <mml:mtd>
 124                       <mml:mrow>
 125                         <mml:mfrac>
 126                           <mml:mrow>
 127                             <mml:mi>&delta;</mml:mi>
 128                             <mml:mi>u</mml:mi>
 129                           </mml:mrow>
 130                           <mml:mrow>
 131                             <mml:mi>&delta;</mml:mi>
 132                             <mml:mi>x</mml:mi>
 133                           </mml:mrow>
 134                         </mml:mfrac>
 135                         <mml:mo>=</mml:mo>
 136                         <mml:mn>0</mml:mn>
 137                         <mml:mo>,</mml:mo>
 138                       </mml:mrow>
 139                     </mml:mtd>
 140                     <mml:mtd>
 141                       <mml:mrow>
 142                         <mml:mfrac>
 143                           <mml:mrow>
 144                             <mml:mi>&delta;</mml:mi>
 145                             <mml:mi>v</mml:mi>
 146                           </mml:mrow>
 147                           <mml:mrow>
 148                             <mml:mi>&delta;</mml:mi>
 149                             <mml:mi>x</mml:mi>
 150                           </mml:mrow>
 151                         </mml:mfrac>
 152                         <mml:mo>=</mml:mo>
 153                         <mml:mn>0</mml:mn>
 154                         <mml:mo>,</mml:mo>
 155                       </mml:mrow>
 156                     </mml:mtd>
 157                     <mml:mtd>
 158                       <mml:mrow>
 159                         <mml:mfrac>
 160                           <mml:mrow>
 161                             <mml:mi>&delta;</mml:mi>
 162                             <mml:mi>w</mml:mi>
 163                           </mml:mrow>
 164                           <mml:mrow>
 165                             <mml:mi>&delta;</mml:mi>
 166                             <mml:mi>x</mml:mi>
 167                           </mml:mrow>
 168                         </mml:mfrac>
 169                         <mml:mo>=</mml:mo>
 170                         <mml:mn>0</mml:mn>
 171                       </mml:mrow>
 172                     </mml:mtd>
 173                   </mml:mtr>
 174                   <mml:mtr>
 175                     <mml:mtd>
 176                       <mml:mrow>
 177                         <mml:mfrac>
 178                           <mml:mrow>
 179                             <mml:mi>&delta;</mml:mi>
 180                             <mml:mi>u</mml:mi>
 181                           </mml:mrow>
 182                           <mml:mrow>
 183                             <mml:mi>&delta;</mml:mi>
 184                             <mml:mi>y</mml:mi>
 185                           </mml:mrow>
 186                         </mml:mfrac>
 187                         <mml:mo>=</mml:mo>
 188                         <mml:mn>0</mml:mn>
 189                         <mml:mo>,</mml:mo>
 190                       </mml:mrow>
 191                     </mml:mtd>
 192                     <mml:mtd>
 193                       <mml:mrow>
 194                         <mml:mfrac>
 195                           <mml:mrow>
 196                             <mml:mi>&delta;</mml:mi>
 197                             <mml:mi>v</mml:mi>
 198                           </mml:mrow>
 199                           <mml:mrow>
 200                             <mml:mi>&delta;</mml:mi>
 201                             <mml:mi>y</mml:mi>
 202                           </mml:mrow>
 203                         </mml:mfrac>
 204                         <mml:mo>=</mml:mo>
 205                         <mml:mn>0</mml:mn>
 206                         <mml:mo>,</mml:mo>
 207                       </mml:mrow>
 208                     </mml:mtd>
 209                     <mml:mtd>
 210                       <mml:mrow>
 211                         <mml:mfrac>
 212                           <mml:mrow>
 213                             <mml:mi>&delta;</mml:mi>
 214                             <mml:mi>w</mml:mi>
 215                           </mml:mrow>
 216                           <mml:mrow>
 217                             <mml:mi>&delta;</mml:mi>
 218                             <mml:mi>y</mml:mi>
 219                           </mml:mrow>
 220                         </mml:mfrac>
 221                         <mml:mo>=</mml:mo>
 222                         <mml:mn>0</mml:mn>
 223                       </mml:mrow>
 224                     </mml:mtd>
 225                   </mml:mtr>
 226                 </mml:mtable>
 227             </mml:math></inlineequation>
 228         </para>
 229     </refsect1>
 230     <refsect1 id="versions"><title>Version Support</title>
 231         <informaltable frame="topbot">
 232             #VARTABLECOLS#
 233                 <thead>
 234                     #FUNCTABLEHEADER#
 235                     <row>
 236                         <entry>textureLod</entry>#newin13#
 237                     </row>
 238                     <row>
 239                         <entry>textureLod (gsampler2DRect{Shadow})</entry>#newin14#
 240                     </row>
 241                     <row>
 242                         <entry>textureLod (gsamplerCubeArray)</entry>#newin40#
 243                     </row>
 244                 </thead>
 245             </tgroup>
 246         </informaltable>
 247     </refsect1>
 248     <refsect1 id="seealso"><title>See Also</title>
 249         <para>
 250             <citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,
 251             <citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,
 252             <citerefentry><refentrytitle>texture</refentrytitle></citerefentry>,
 253             <citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry>,
 254             <citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
 255             <citerefentry><refentrytitle>textureGatherOffsets</refentrytitle></citerefentry>,
 256             <citerefentry><refentrytitle>textureGrad</refentrytitle></citerefentry>,
 257             <citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,
 258             <citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,
 259             <citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,
 260             <citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,
 261             <citerefentry><refentrytitle>textureProjGrad</refentrytitle></citerefentry>,
 262             <citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,
 263             <citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,
 264             <citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,
 265             <citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,
 266             <citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,
 267             <citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>
 268         </para>
 269     </refsect1>
 270     <refsect1 id="Copyright"><title>Copyright</title>
 271         <para>
 272             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 273             This material may be distributed subject to the terms and conditions set forth in
 274             the Open Publication License, v 1.0, 8 June 1999.
 275             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 276         </para>
 277     </refsect1>
 278 </refentry>