vcglib/vcg/math/polar_decomposition.h

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/****************************************************************************
* VCGLib o o *
* Visual and Computer Graphics Library o o *
* _ O _ *
* Copyright(C) 2004 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
/****************************************************************************
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****************************************************************************/
#ifndef POLAR_DECOMPOSITION_VCG
#define POLAR_DECOMPOSITION_VCG
#include <vcg/math/matrix33.h>
#include <vcg/math/matrix44.h>
#include <vcg/math/lin_algebra.h>
namespace vcg{
/** \addtogroup math */
/* @{ */
/// Extract the rotational part of a matrix by polar decomposition
/// m = R*S. Polar decomposition is computed by taking r = m * sqrt(m^t*m)^{-1}
template <class S>
void RotationalPartByPolarDecomposition( const vcg::Matrix33<S> & m, vcg::Matrix33<S> &r ){
vcg::Matrix33<S> tmp,s;
r.SetZero();
s.SetZero();
tmp = m*m.transpose();
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Matrix33<S> res;
Point3<S> e;
bool ss = SingularValueDecomposition<vcg::Matrix33<S> >(tmp,&e[0],res);
e[0]=math::Sqrt(e[0]);
e[1]=math::Sqrt(e[1]);
e[2]=math::Sqrt(e[2]);
#ifdef VCG_USE_EIGEN
tmp = tmp*e.asDiagonal()*res.transpose();
#else
tmp = tmp*Matrix33Diag<S>(e)*res.transpose();
#endif
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bool s1 = SingularValueDecomposition<vcg::Matrix33<S> >(tmp,&e[0],res.transpose());
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e[0]=1/e[0];
e[1]=1/e[1];
e[2]=1/e[2];
#ifdef VCG_USE_EIGEN
tmp = res*e.asDiagonal()*tmp.transpose();
#else
tmp = res*Matrix33Diag<S>(e)*tmp.transpose();
#endif
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r = m*tmp;
}
/*! @} */
};
#endif