'\" t
.\"     Title: refract
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 05/21/2015
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "REFRACT" "3G" "05/21/2015" "[FIXME: source]" "[FIXME: manual]"
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.SH "NAME"
refract \- calculate the refraction direction for an incident vector
.SH "DECLARATION"
.HP \w'genType\ refract('u
.BI "genType refract(genType\ " "I" ", genType\ " "N" ", float\ " "eta" ");"
.HP \w'genDType\ refract('u
.BI "genDType refract(genDType\ " "I" ", genDType\ " "N" ", float\ " "eta" ");"
.SH "PARAMETERS"
.PP
\fII\fR
.RS 4
Specifies the incident vector\&.
.RE
.PP
\fIN\fR
.RS 4
Specifies the normal vector\&.
.RE
.PP
\fIeta\fR
.RS 4
Specifies the ratio of indices of refraction\&.
.RE
.SH "DESCRIPTION"
.PP
For a given incident vector
\fII\fR, surface normal
\fIN\fR
and ratio of indices of refraction,
\fIeta\fR,
\fBrefract\fR
returns the refraction vector,
\fIR\fR\&.
.PP
\fIR\fR
is calculated as:
.PP
.if n \{\
.RS 4
.\}
.nf
    k = 1\&.0 \- eta * eta * (1\&.0 \- dot(N, I) * dot(N, I));
    if (k < 0\&.0)
        R = genType(0\&.0);       // or genDType(0\&.0)
    else
        R = eta * I \- (eta * dot(N, I) + sqrt(k)) * N;
.fi
.if n \{\
.RE
.\}
.PP
The input parameters
\fII\fR
and
\fIN\fR
should be normalized in order to achieve the desired result\&.
.SH "VERSION SUPPORT"
.TS
allbox tab(:);
lB cB s s s s s s s s s s s
lB cB cB cB cB cB cB cB cB cB cB cB cB.
T{

T}:T{
\fBOpenGL Shading Language Version\fR
T}
T{
\fBFunction Name\fR
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\fB1\&.10\fR
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\fB1\&.20\fR
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\fB1\&.30\fR
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\fB1\&.40\fR
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\fB1\&.50\fR
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\fB3\&.30\fR
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\fB4\&.00\fR
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\fB4\&.10\fR
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\fB4\&.20\fR
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\fB4\&.30\fR
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\fB4\&.40\fR
T}:T{
\fB4\&.50\fR
T}
.T&
l c c c c c c c c c c c c
l c c c c c c c c c c c c.
T{
refract (genType)
T}:T{
✔
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✔
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T}
T{
refract (genDType)
T}:T{
\-
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\-
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\-
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\-
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\-
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\-
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.TE
.sp
.SH "SEE ALSO"
.PP
\fBdot\fR(),
\fBreflect\fR()
.SH "COPYRIGHT"
.PP
Copyright
\(co
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\&.
\m[blue]\fBhttp://opencontent\&.org/openpub/\fR\m[]\&.
.SH "COPYRIGHT"
.br
Copyright \(co 2011-2014 Khronos Group
.br