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1 | <?xml version="1.0" encoding="UTF-8"?>\r |
2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"\r | |
3 | "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">\r | |
4 | <refentry id="smoothstep">\r | |
5 | <refmeta>\r | |
6 | <refmetainfo>\r | |
7 | <copyright>\r | |
8 | <year>2011</year>\r | |
9 | <holder>Khronos Group</holder>\r | |
10 | </copyright>\r | |
11 | </refmetainfo>\r | |
12 | <refentrytitle>smoothstep</refentrytitle>\r | |
13 | <manvolnum>3G</manvolnum>\r | |
14 | </refmeta>\r | |
15 | <refnamediv>\r | |
16 | <refname>smoothstep</refname>\r | |
17 | <refpurpose>perform Hermite interpolation between two values</refpurpose>\r | |
18 | </refnamediv>\r | |
19 | <refsynopsisdiv><title>Declaration</title>\r | |
20 | <funcsynopsis>\r | |
21 | <funcprototype>\r | |
22 | <funcdef>genType <function>smoothstep</function></funcdef>\r | |
23 | <paramdef>genType <parameter>edge0</parameter></paramdef>\r | |
24 | <paramdef>genType <parameter>edge1</parameter></paramdef>\r | |
25 | <paramdef>genType <parameter>x</parameter></paramdef>\r | |
26 | </funcprototype>\r | |
27 | </funcsynopsis>\r | |
28 | <funcsynopsis>\r | |
29 | <funcprototype>\r | |
30 | <funcdef>genType <function>smoothstep</function></funcdef>\r | |
31 | <paramdef>float <parameter>edge0</parameter></paramdef>\r | |
32 | <paramdef>float <parameter>edge1</parameter></paramdef>\r | |
33 | <paramdef>genType <parameter>x</parameter></paramdef>\r | |
34 | </funcprototype>\r | |
35 | </funcsynopsis>\r | |
36 | <funcsynopsis>\r | |
37 | <funcprototype>\r | |
38 | <funcdef>genDType <function>smoothstep</function></funcdef>\r | |
39 | <paramdef>genDType <parameter>edge0</parameter></paramdef>\r | |
40 | <paramdef>genDType <parameter>edge1</parameter></paramdef>\r | |
41 | <paramdef>genDType <parameter>x</parameter></paramdef>\r | |
42 | </funcprototype>\r | |
43 | </funcsynopsis>\r | |
44 | <funcsynopsis>\r | |
45 | <funcprototype>\r | |
46 | <funcdef>genDType <function>smoothstep</function></funcdef>\r | |
47 | <paramdef>double <parameter>edge0</parameter></paramdef>\r | |
48 | <paramdef>double <parameter>edge1</parameter></paramdef>\r | |
49 | <paramdef>genDType <parameter>x</parameter></paramdef>\r | |
50 | </funcprototype>\r | |
51 | </funcsynopsis>\r | |
52 | </refsynopsisdiv>\r | |
53 | <refsect1 id="parameters"><title>Parameters</title>\r | |
54 | <variablelist>\r | |
55 | <varlistentry>\r | |
56 | <term><parameter>edge0</parameter></term>\r | |
57 | <listitem>\r | |
58 | <para>\r | |
59 | Specifies the value of the lower edge of the Hermite function.\r | |
60 | </para>\r | |
61 | </listitem>\r | |
62 | </varlistentry>\r | |
63 | <varlistentry>\r | |
64 | <term><parameter>edge1</parameter></term>\r | |
65 | <listitem>\r | |
66 | <para>\r | |
67 | Specifies the value of the upper edge of the Hermite function.\r | |
68 | </para>\r | |
69 | </listitem>\r | |
70 | </varlistentry>\r | |
71 | <varlistentry>\r | |
72 | <term><parameter>x</parameter></term>\r | |
73 | <listitem>\r | |
74 | <para>\r | |
75 | Specifies the source value for interpolation.\r | |
76 | </para>\r | |
77 | </listitem>\r | |
78 | </varlistentry>\r | |
79 | </variablelist>\r | |
80 | </refsect1>\r | |
81 | <refsect1 id="description"><title>Description</title>\r | |
82 | <para>\r | |
83 | <function>smoothstep</function> performs smooth Hermite interpolation between 0 and\r | |
84 | 1 when <parameter>edge0</parameter> < <parameter>x</parameter> < <parameter>edge1</parameter>.\r | |
85 | This is useful in cases where a threshold function with a smooth transition is desired.\r | |
86 | <function>smoothstep</function> is equivalent to:\r | |
87 | </para>\r | |
88 | <para>\r | |
89 | <programlisting><![CDATA[ genType t; /* Or genDType t; */\r | |
90 | t = clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0);\r | |
91 | return t * t * (3.0 - 2.0 * t);\r | |
92 | ]]></programlisting>\r | |
93 | </para>\r | |
94 | <para>\r | |
95 | Results are undefined if <parameter>edge0</parameter> ≥ <parameter>edge1</parameter>.\r | |
96 | </para>\r | |
97 | </refsect1>\r | |
98 | <refsect1 id="versions"><title>Version Support</title>\r | |
99 | <informaltable frame="topbot">\r | |
100 | #VARTABLECOLS#\r | |
101 | <thead>\r | |
102 | #FUNCTABLEHEADER#\r | |
103 | <row>\r | |
104 | <entry>smoothstep (genType)</entry>#newin13#\r | |
105 | </row>\r | |
106 | <row>\r | |
107 | <entry>smoothstep (genDType)</entry>#newin40#\r | |
108 | </row>\r | |
109 | </thead>\r | |
110 | </tgroup>\r | |
111 | </informaltable>\r | |
112 | </refsect1>\r | |
113 | <refsect1 id="seealso"><title>See Also</title>\r | |
114 | <para>\r | |
115 | <citerefentry><refentrytitle>mix</refentrytitle></citerefentry>,\r | |
116 | <citerefentry><refentrytitle>step</refentrytitle></citerefentry>\r | |
117 | </para>\r | |
118 | </refsect1>\r | |
119 | <refsect1 id="Copyright"><title>Copyright</title>\r | |
120 | <para>\r | |
121 | Copyright <trademark class="copyright"></trademark> 2011 Khronos Group. \r | |
122 | This material may be distributed subject to the terms and conditions set forth in \r | |
123 | the Open Publication License, v 1.0, 8 June 1999.\r | |
124 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.\r | |
125 | </para>\r | |
126 | </refsect1>\r | |
127 | </refentry>\r |