upstream-doc/manglsl/dFdx.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="dFdx">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>dFdx, dFdy</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>dFdx, dFdy</refname>
  17         <refpurpose>return the partial derivative of an argument with respect to x or y</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>genType <function>dFdx</function></funcdef>
  23                 <paramdef>genType <parameter>p</parameter></paramdef>
  24             </funcprototype>
  25             <funcprototype>
  26                 <funcdef>genType <function>dFdy</function></funcdef>
  27                 <paramdef>genType <parameter>p</parameter></paramdef>
  28             </funcprototype>
  29         </funcsynopsis>
  30     </refsynopsisdiv>
  31     <refsect1 id="parameters"><title>Parameters</title>
  32         <variablelist>
  33         <varlistentry>
  34             <term><parameter>p</parameter></term>
  35             <listitem>
  36                 <para>
  37                     Specifies the expression of which to take the partial derivative.
  38                 </para>
  39             </listitem>
  40         </varlistentry>
  41         </variablelist>
  42     </refsect1>
  43     <refsect1 id="description"><title>Description</title>
  44         <para>
  45             <emphasis>Available only in the fragment shader</emphasis>, <function>dFdx</function> and <function>dFdy</function>
  46             return the partial derivative of expression <parameter>p</parameter> in x and y, respectively. Deviatives are calculated
  47             using local differencing. Expressions that imply higher order derivatives such as <code>dFdx(dFdx(n))</code> have undefined
  48             results, as do mixed-order derivatives such as <code>dFdx(dFdy(n))</code>.
  49             It is assumed that the expression <parameter>p</parameter> is continuous and therefore, expressions evaluated
  50             via non-uniform control flow may be undefined.
  51         </para>
  52     </refsect1>
  53     <refsect1 id="versions"><title>Version Support</title>
  54         <informaltable frame="topbot">
  55             #VARTABLECOLS#
  56                 <thead>
  57                     #FUNCTABLEHEADER#
  58                     <row>
  59                         <entry>dFdx</entry>#newin11#
  60                     </row>
  61                     <row>
  62                         <entry>dFdy</entry>#newin11#
  63                     </row>
  64                 </thead>
  65             </tgroup>
  66         </informaltable>
  67     </refsect1>
  68     <refsect1 id="seealso"><title>See Also</title>
  69         <para>
  70             <citerefentry><refentrytitle>fwidth</refentrytitle></citerefentry>
  71         </para>
  72     </refsect1>
  73     <refsect1 id="Copyright"><title>Copyright</title>
  74         <para>
  75             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
  76             This material may be distributed subject to the terms and conditions set forth in
  77             the Open Publication License, v 1.0, 8 June 1999.
  78             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
  79         </para>
  80     </refsect1>
  81 </refentry>