HCoop / clinton / guile-figl.git / blame
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1 | <?xml version="1.0" encoding="UTF-8"?> |
| 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> | |
| 3 | <!-- saved from url=(0013)about:internet --> | |
| 4 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="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>. | |
| 14 | </p><p> | |
| 15 | <em class="parameter"><code>R</code></em> is calculated as: | |
| 16 | </p><p> | |
| 17 | </p><pre class="programlisting"> k = 1.0 - eta * eta * (1.0 - dot(N, I) * dot(N, I)); | |
| 18 | if (k < 0.0) | |
| 19 | R = genType(0.0); // or genDType(0.0) | |
| 20 | else | |
| 21 | R = eta * I - (eta * dot(N, I) + sqrt(k)) * N;</pre><p> | |
| 22 | </p><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> |