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renderer=
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"text/html; charset=UTF-8" /><link rel=
"stylesheet" type=
"text/css" href=
"opengl-man.css" /><title>refract - OpenGL Shading Language (GLSL)
</title><meta name=
"generator" content=
"DocBook XSL Stylesheets V1.69.1" /></head><body><div class=
"refentry" lang=
"en" xml:
lang=
"en"><a id=
"refract"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>refract — calculate the refraction direction for an incident vector
</p></div><div class=
"refsynopsisdiv"><h2>Declaration
</h2><div class=
"funcsynopsis"><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0" style=
"padding-bottom: 1em"><tr><td><code class=
"funcdef">genType
<b class=
"fsfunc">refract
</b>(
</code></td><td>genType
</td><td><var class=
"pdparam">I
</var>,
</td></tr><tr><td> </td><td>genType
</td><td><var class=
"pdparam">N
</var>,
</td></tr><tr><td> </td><td>float
</td><td><var class=
"pdparam">eta
</var><code>)
</code>;
</td></tr></table><table border=
"0" summary=
"Function synopsis" cellspacing=
"0" cellpadding=
"0"><tr><td><code class=
"funcdef">genDType
<b class=
"fsfunc">refract
</b>(
</code></td><td>genDType
</td><td><var class=
"pdparam">I
</var>,
</td></tr><tr><td> </td><td>genDType
</td><td><var class=
"pdparam">N
</var>,
</td></tr><tr><td> </td><td>float
</td><td><var class=
"pdparam">eta
</var><code>)
</code>;
</td></tr></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"parameters"></a><h2>Parameters
</h2><div class=
"variablelist"><dl><dt><span class=
"term"><em class=
"parameter"><code>I
</code></em></span></dt><dd><p>
5 Specifies the incident vector.
6 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>N
</code></em></span></dt><dd><p>
7 Specifies the normal vector.
8 </p></dd><dt><span class=
"term"><em class=
"parameter"><code>eta
</code></em></span></dt><dd><p>
9 Specifies the ratio of indices of refraction.
10 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
11 For a given incident vector
<em class=
"parameter"><code>I
</code></em>, surface normal
<em class=
"parameter"><code>N
</code></em> and ratio of
12 indices of refraction,
<em class=
"parameter"><code>eta
</code></em>,
<code class=
"function">refract
</code> returns the refraction vector,
13 <em class=
"parameter"><code>R
</code></em>.
15 <em class=
"parameter"><code>R
</code></em> is calculated as:
17 </p><pre class=
"programlisting"> k =
1.0 - eta * eta * (
1.0 - dot(N, I) * dot(N, I));
19 R = genType(
0.0); // or genDType(
0.0)
21 R = eta * I - (eta * dot(N, I) + sqrt(k)) * N;
</pre><p>
23 The input parameters
<em class=
"parameter"><code>I
</code></em> and
<em class=
"parameter"><code>N
</code></em> should be normalized in order to achieve the desired result.
24 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"versions"></a><h2>Version Support
</h2><div class=
"informaltable"><table border=
"1"><colgroup><col align=
"left" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /><col align=
"center" /></colgroup><thead><tr><th align=
"left"><span class=
"bold"><strong>Function
</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.10</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.20</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.30</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.40</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
1.50</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
3.30</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.00</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.10</strong></span></th><th align=
"left"><span class=
"bold"><strong>Version
4.20</strong></span></th><th align=
"center"><span class=
"bold"><strong>Version
4.30</strong></span></th></tr><tr><th align=
"left">refract (genType)
</th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th></tr><tr><th align=
"left">refract (genDType)
</th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>-
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th><th align=
"center"><span class=
"emphasis"><em>Y
</em></span></th></tr></thead></table></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"seealso"></a><h2>See Also
</h2><p>
25 <a href=
"dot.xml"><span class=
"citerefentry"><span class=
"refentrytitle">dot
</span></span></a>,
26 <a href=
"reflect.xml"><span class=
"citerefentry"><span class=
"refentrytitle">reflect
</span></span></a>
27 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
28 Copyright
<span class=
"trademark"></span>©
2011 Khronos Group.
29 This material may be distributed subject to the terms and conditions set forth in
30 the Open Publication License, v
1.0,
8 June
1999.
31 <a href=
"http://opencontent.org/openpub/" target=
"_top">http://opencontent.org/openpub/
</a>.
32 </p></div></div></body></html>