upstream-doc/manglsl/reflect.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="reflect">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>reflect</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>reflect</refname>
  17         <refpurpose>calculate the reflection direction for an incident vector</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>genType <function>reflect</function></funcdef>
  23                 <paramdef>genType <parameter>I</parameter></paramdef>
  24                 <paramdef>genType <parameter>N</parameter></paramdef>
  25             </funcprototype>
  26             <funcprototype>
  27                 <funcdef>genDType <function>reflect</function></funcdef>
  28                 <paramdef>genDType <parameter>I</parameter></paramdef>
  29                 <paramdef>genDType <parameter>N</parameter></paramdef>
  30             </funcprototype>
  31         </funcsynopsis>
  32     </refsynopsisdiv>
  33     <refsect1 id="parameters"><title>Parameters</title>
  34         <variablelist>
  35         <varlistentry>
  36             <term><parameter>I</parameter></term>
  37             <listitem>
  38                 <para>
  39                     Specifies the incident vector.
  40                 </para>
  41             </listitem>
  42         </varlistentry>
  43         <varlistentry>
  44             <term><parameter>N</parameter></term>
  45             <listitem>
  46                 <para>
  47                     Specifies the normal vector.
  48                 </para>
  49             </listitem>
  50         </varlistentry>
  51         </variablelist>
  52     </refsect1>
  53     <refsect1 id="description"><title>Description</title>
  54         <para>
  55             For a given incident vector <parameter>I</parameter> and surface normal <parameter>N</parameter> <function>reflect</function> returns
  56             the reflection direction calculated as <code><parameter>I</parameter> - 2.0 * <citerefentry><refentrytitle>dot</refentrytitle></citerefentry>(<parameter>N</parameter>, <parameter>I</parameter>) * <parameter>N</parameter></code>.
  57         </para>
  58         <para>
  59             <parameter>N</parameter> should be normalized in order to achieve the desired result.
  60         </para>
  61     </refsect1>
  62     <refsect1 id="versions"><title>Version Support</title>
  63         <informaltable frame="topbot">
  64             #VARTABLECOLS#
  65                 <thead>
  66                     #FUNCTABLEHEADER#
  67                     <row>
  68                         <entry>reflect (genType)</entry>#newin11#
  69                     </row>
  70                     <row>
  71                         <entry>reflect (genDType)</entry>#newin40#
  72                     </row>
  73                 </thead>
  74             </tgroup>
  75         </informaltable>
  76     </refsect1>
  77     <refsect1 id="seealso"><title>See Also</title>
  78         <para>
  79             <citerefentry><refentrytitle>dot</refentrytitle></citerefentry>,
  80             <citerefentry><refentrytitle>refract</refentrytitle></citerefentry>
  81         </para>
  82     </refsect1>
  83     <refsect1 id="Copyright"><title>Copyright</title>
  84         <para>
  85             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
  86             This material may be distributed subject to the terms and conditions set forth in
  87             the Open Publication License, v 1.0, 8 June 1999.
  88             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
  89         </para>
  90     </refsect1>
  91 </refentry>