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">
9 <holder>Khronos Group
</holder>
12 <refentrytitle>dFdx, dFdy
</refentrytitle>
13 <manvolnum>3G
</manvolnum>
16 <refname>dFdx, dFdy
</refname>
17 <refpurpose>return the partial derivative of an argument with respect to x or y
</refpurpose>
19 <refsynopsisdiv><title>Declaration
</title>
22 <funcdef>genType
<function>dFdx
</function></funcdef>
23 <paramdef>genType
<parameter>p
</parameter></paramdef>
26 <funcdef>genType
<function>dFdy
</function></funcdef>
27 <paramdef>genType
<parameter>p
</parameter></paramdef>
31 <refsect1 id=
"parameters"><title>Parameters
</title>
34 <term><parameter>p
</parameter></term>
37 Specifies the expression of which to take the partial derivative.
43 <refsect1 id=
"description"><title>Description
</title>
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.
53 <refsect1 id=
"versions"><title>Version Support
</title>
54 <informaltable frame=
"topbot">
59 <entry>dFdx
</entry>#newin11#
62 <entry>dFdy
</entry>#newin11#
68 <refsect1 id=
"seealso"><title>See Also
</title>
70 <citerefentry><refentrytitle>fwidth
</refentrytitle></citerefentry>
73 <refsect1 id=
"Copyright"><title>Copyright
</title>
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>.