38 lines
930 B
C++
38 lines
930 B
C++
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// This file is part of libigl, a simple c++ geometry processing library.
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//
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// Copyright (C) 2018 Alec Jacobson <alecjacobson@gmail.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License
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// v. 2.0. If a copy of the MPL was not distributed with this file, You can
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// obtain one at http://mozilla.org/MPL/2.0/.
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#include "tan_half_angle.h"
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#include <cmath>
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template < typename Scalar>
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IGL_INLINE Scalar igl::tan_half_angle(
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const Scalar & a,
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const Scalar & b,
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const Scalar & c)
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{
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// .
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// /|
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// c/ |
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// / |
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// / |
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// .α | a
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// \ |
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// \ |
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// b\ |
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// \|
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//
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// tan(α/2)
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// Fisher 2007
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return sqrt(((a-b+c)*(a+b-c))/((a+b+c)*(-a+b+c)));
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}
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#ifdef IGL_STATIC_LIBRARY
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// Explicit template instantiation
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// generated by autoexplicit.sh
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template double igl::tan_half_angle<double>(double const&, double const&, double const&);
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#endif
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