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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
<!-- Converted by db4-upgrade version 1.1 -->
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="smoothstep">
<info>
<copyright>
<year>2011-2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>smoothstep</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>smoothstep</refname>
<refpurpose>perform Hermite interpolation between two values</refpurpose>
</refnamediv>
<refsynopsisdiv><title>Declaration</title>
<funcsynopsis>
<funcprototype>
<funcdef>genType <function>smoothstep</function></funcdef>
<paramdef>genType <parameter>edge0</parameter></paramdef>
<paramdef>genType <parameter>edge1</parameter></paramdef>
<paramdef>genType <parameter>x</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>genType <function>smoothstep</function></funcdef>
<paramdef>float <parameter>edge0</parameter></paramdef>
<paramdef>float <parameter>edge1</parameter></paramdef>
<paramdef>genType <parameter>x</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>genDType <function>smoothstep</function></funcdef>
<paramdef>genDType <parameter>edge0</parameter></paramdef>
<paramdef>genDType <parameter>edge1</parameter></paramdef>
<paramdef>genDType <parameter>x</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>genDType <function>smoothstep</function></funcdef>
<paramdef>double <parameter>edge0</parameter></paramdef>
<paramdef>double <parameter>edge1</parameter></paramdef>
<paramdef>genDType <parameter>x</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>edge0</parameter></term>
<listitem>
<para>
Specifies the value of the lower edge of the Hermite function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>edge1</parameter></term>
<listitem>
<para>
Specifies the value of the upper edge of the Hermite function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>x</parameter></term>
<listitem>
<para>
Specifies the source value for interpolation.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>smoothstep</function> performs smooth Hermite interpolation between 0 and
1 when <parameter>edge0</parameter> < <parameter>x</parameter> < <parameter>edge1</parameter>.
This is useful in cases where a threshold function with a smooth transition is desired.
<function>smoothstep</function> is equivalent to:
</para>
<para>
<programlisting> genType t; /* Or genDType t; */
t = clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0);
return t * t * (3.0 - 2.0 * t);</programlisting>
</para>
<para>
Results are undefined if <parameter>edge0</parameter> ≥ <parameter>edge1</parameter>.
</para>
</refsect1>
<refsect1 xml:id="versions"><title>Version Support</title>
<informaltable>
<tgroup cols="13" align="left">
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="funchead.xml" xpointer="xpointer(/*/*)"/>
<tbody>
<row>
<entry>smoothstep (genType)</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='13']/*)"/>
</row>
<row>
<entry>smoothstep (genDType)</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='40']/*)"/>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 xml:id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>mix</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>step</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 xml:id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"/> 2011-2014 Khronos Group.
This material may be distributed subject to the terms and conditions set forth in
the Open Publication License, v 1.0, 8 June 1999.
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
</para>
</refsect1>
</refentry>
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