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igl/include/igl/n_polyvector_general.cpp
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2015-06-29 12:10:54 +02:00

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// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2014 Olga Diamanti <olga.diam@gmail.com>
//
// This Source Code Form is subject to the terms of the Mozilla Public License
// v. 2.0. If a copy of the MPL was not distributed with this file, You can
// obtain one at http://mozilla.org/MPL/2.0/.
#include <igl/n_polyvector_general.h>
#include <igl/edge_topology.h>
#include <igl/local_basis.h>
#include <igl/nchoosek.h>
#include <igl/slice.h>
#include <igl/polyroots.h>
#include <Eigen/Sparse>
#include <Eigen/Geometry>
#include <iostream>
namespace igl {
template <typename DerivedV, typename DerivedF>
class GeneralPolyVectorFieldFinder
{
private:
const Eigen::PlainObjectBase<DerivedV> &V;
const Eigen::PlainObjectBase<DerivedF> &F; int numF;
const int n;
Eigen::MatrixXi EV; int numE;
Eigen::MatrixXi F2E;
Eigen::MatrixXi E2F;
Eigen::VectorXd K;
Eigen::VectorXi isBorderEdge;
int numInteriorEdges;
Eigen::Matrix<int,Eigen::Dynamic,2> E2F_int;
Eigen::VectorXi indInteriorToFull;
Eigen::VectorXi indFullToInterior;
Eigen::PlainObjectBase<DerivedV> B1, B2, FN;
IGL_INLINE void computek();
IGL_INLINE void setFieldFromGeneralCoefficients(const std::vector<Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1>> &coeffs,
std::vector<Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, 2> > &pv);
IGL_INLINE void computeCoefficientLaplacian(int n, Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > &D);
IGL_INLINE void getGeneralCoeffConstraints(const Eigen::VectorXi &isConstrained,
const Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, Eigen::Dynamic> &cfW,
int k,
const Eigen::VectorXi &rootsIndex,
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1> &Ck);
IGL_INLINE void precomputeInteriorEdges();
IGL_INLINE void minQuadWithKnownMini(const Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > &Q,
const Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > &f,
const Eigen::VectorXi isConstrained,
const Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic, 1> &xknown,
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic, 1> &x);
public:
IGL_INLINE GeneralPolyVectorFieldFinder(const Eigen::PlainObjectBase<DerivedV> &_V,
const Eigen::PlainObjectBase<DerivedF> &_F,
const int &_n);
IGL_INLINE bool solve(const Eigen::VectorXi &isConstrained,
const Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, Eigen::Dynamic> &cfW,
const Eigen::VectorXi &rootsIndex,
Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, Eigen::Dynamic> &output);
};
}
template<typename DerivedV, typename DerivedF>
IGL_INLINE igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::
GeneralPolyVectorFieldFinder(const Eigen::PlainObjectBase<DerivedV> &_V,
const Eigen::PlainObjectBase<DerivedF> &_F,
const int &_n):
V(_V),
F(_F),
numF(_F.rows()),
n(_n)
{
igl::edge_topology(V,F,EV,F2E,E2F);
numE = EV.rows();
precomputeInteriorEdges();
igl::local_basis(V,F,B1,B2,FN);
computek();
};
template<typename DerivedV, typename DerivedF>
IGL_INLINE void igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::
precomputeInteriorEdges()
{
// Flag border edges
numInteriorEdges = 0;
isBorderEdge.setZero(numE,1);
indFullToInterior = -1*Eigen::VectorXi::Ones(numE,1);
for(unsigned i=0; i<numE; ++i)
{
if ((E2F(i,0) == -1) || ((E2F(i,1) == -1)))
isBorderEdge[i] = 1;
else
{
indFullToInterior[i] = numInteriorEdges;
numInteriorEdges++;
}
}
E2F_int.resize(numInteriorEdges, 2);
indInteriorToFull.setZero(numInteriorEdges,1);
int ii = 0;
for (int k=0; k<numE; ++k)
{
if (isBorderEdge[k])
continue;
E2F_int.row(ii) = E2F.row(k);
indInteriorToFull[ii] = k;
ii++;
}
}
template<typename DerivedV, typename DerivedF>
IGL_INLINE void igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::
minQuadWithKnownMini(const Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > &Q,
const Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > &f,
const Eigen::VectorXi isConstrained,
const Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic, 1> &xknown,
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic, 1> &x)
{
int N = Q.rows();
int nc = xknown.rows();
Eigen::VectorXi known; known.setZero(nc,1);
Eigen::VectorXi unknown; unknown.setZero(N-nc,1);
int indk = 0, indu = 0;
for (int i = 0; i<N; ++i)
if (isConstrained[i])
{
known[indk] = i;
indk++;
}
else
{
unknown[indu] = i;
indu++;
}
Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar>> Quu, Quk;
igl::slice(Q,unknown, unknown, Quu);
igl::slice(Q,unknown, known, Quk);
std::vector<typename Eigen::Triplet<std::complex<typename DerivedV::Scalar> > > tripletList;
Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > fu(N-nc,1);
igl::slice(f,unknown, Eigen::VectorXi::Zero(1,1), fu);
Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > rhs = (Quk*xknown).sparseView()+.5*fu;
Eigen::SparseLU< Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar>>> solver;
solver.compute(-Quu);
if(solver.info()!=Eigen::Success)
{
std::cerr<<"Decomposition failed!"<<std::endl;
return;
}
Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar>> b = solver.solve(rhs);
if(solver.info()!=Eigen::Success)
{
std::cerr<<"Solving failed!"<<std::endl;
return;
}
indk = 0, indu = 0;
x.setZero(N,1);
for (int i = 0; i<N; ++i)
if (isConstrained[i])
x[i] = xknown[indk++];
else
x[i] = b.coeff(indu++,0);
}
template<typename DerivedV, typename DerivedF>
IGL_INLINE bool igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::
solve(const Eigen::VectorXi &isConstrained,
const Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, Eigen::Dynamic> &cfW,
const Eigen::VectorXi &rootsIndex,
Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, Eigen::Dynamic> &output)
{
// polynomial is of the form:
// z^(2n) +
// -c[0]z^(2n-1) +
// c[1]z^(2n-2) +
// -c[2]z^(2n-3) +
// ... +
// (-1)^n c[n-1]
std::vector<Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1>> coeffs(n,Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1>::Zero(numF, 1));
for (int i =0; i<n; ++i)
{
int degree = i+1;
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1> Ck;
getGeneralCoeffConstraints(isConstrained,
cfW,
i,
rootsIndex,
Ck);
Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > DD;
computeCoefficientLaplacian(degree, DD);
Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > f; f.resize(numF,1);
if (isConstrained.sum() == numF)
coeffs[i] = Ck;
else
minQuadWithKnownMini(DD, f, isConstrained, Ck, coeffs[i]);
}
std::vector<Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, 2> > pv;
setFieldFromGeneralCoefficients(coeffs, pv);
output.setZero(numF,3*n);
for (int fi=0; fi<numF; ++fi)
{
const Eigen::Matrix<typename DerivedV::Scalar, 1, 3> &b1 = B1.row(fi);
const Eigen::Matrix<typename DerivedV::Scalar, 1, 3> &b2 = B2.row(fi);
for (int i=0; i<n; ++i)
output.block(fi,3*i, 1, 3) = pv[i](fi,0)*b1 + pv[i](fi,1)*b2;
}
return true;
}
template<typename DerivedV, typename DerivedF>
IGL_INLINE void igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::setFieldFromGeneralCoefficients(const std::vector<Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1>> &coeffs,
std::vector<Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, 2>> &pv)
{
pv.assign(n, Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, 2>::Zero(numF, 2));
for (int i = 0; i <numF; ++i)
{
// poly coefficients: 1, 0, -Acoeff, 0, Bcoeff
// matlab code from roots (given there are no trailing zeros in the polynomial coefficients)
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1> polyCoeff;
polyCoeff.setZero(n+1,1);
polyCoeff[0] = 1.;
int sign = 1;
for (int k =0; k<n; ++k)
{
sign = -sign;
int degree = k+1;
polyCoeff[degree] = (1.*sign)*coeffs[k](i);
}
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1> roots;
igl::polyRoots<std::complex<typename DerivedV::Scalar>, typename DerivedV::Scalar >(polyCoeff,roots);
for (int k=0; k<n; ++k)
{
pv[k](i,0) = real(roots[k]);
pv[k](i,1) = imag(roots[k]);
}
}
}
template<typename DerivedV, typename DerivedF>
IGL_INLINE void igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::computeCoefficientLaplacian(int n, Eigen::SparseMatrix<std::complex<typename DerivedV::Scalar> > &D)
{
std::vector<Eigen::Triplet<std::complex<typename DerivedV::Scalar> >> tripletList;
// For every non-border edge
for (unsigned eid=0; eid<numE; ++eid)
{
if (!isBorderEdge[eid])
{
int fid0 = E2F(eid,0);
int fid1 = E2F(eid,1);
tripletList.push_back(Eigen::Triplet<std::complex<typename DerivedV::Scalar> >(fid0,
fid0,
std::complex<typename DerivedV::Scalar>(1.)));
tripletList.push_back(Eigen::Triplet<std::complex<typename DerivedV::Scalar> >(fid1,
fid1,
std::complex<typename DerivedV::Scalar>(1.)));
tripletList.push_back(Eigen::Triplet<std::complex<typename DerivedV::Scalar> >(fid0,
fid1,
-1.*std::polar(1.,-1.*n*K[eid])));
tripletList.push_back(Eigen::Triplet<std::complex<typename DerivedV::Scalar> >(fid1,
fid0,
-1.*std::polar(1.,1.*n*K[eid])));
}
}
D.resize(numF,numF);
D.setFromTriplets(tripletList.begin(), tripletList.end());
}
//this gives the coefficients without the (-1)^k that multiplies them
template<typename DerivedV, typename DerivedF>
IGL_INLINE void igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::getGeneralCoeffConstraints(const Eigen::VectorXi &isConstrained,
const Eigen::Matrix<typename DerivedV::Scalar, Eigen::Dynamic, Eigen::Dynamic> &cfW,
int k,
const Eigen::VectorXi &rootsIndex,
Eigen::Matrix<std::complex<typename DerivedV::Scalar>, Eigen::Dynamic,1> &Ck)
{
int numConstrained = isConstrained.sum();
Ck.resize(numConstrained,1);
// int n = rootsIndex.cols();
Eigen::MatrixXi allCombs;
{
Eigen::VectorXi V = Eigen::VectorXi::LinSpaced(n,0,n-1);
igl::nchoosek(V,k+1,allCombs);
}
int ind = 0;
for (int fi = 0; fi <numF; ++fi)
{
const Eigen::Matrix<typename DerivedV::Scalar, 1, 3> &b1 = B1.row(fi);
const Eigen::Matrix<typename DerivedV::Scalar, 1, 3> &b2 = B2.row(fi);
if(isConstrained[fi])
{
std::complex<typename DerivedV::Scalar> ck(0);
for (int j = 0; j < allCombs.rows(); ++j)
{
std::complex<typename DerivedV::Scalar> tk(1.);
//collect products
for (int i = 0; i < allCombs.cols(); ++i)
{
int index = allCombs(j,i);
int ri = rootsIndex[index];
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> w;
if (ri>0)
w = cfW.block(fi,3*(ri-1),1,3);
else
w = -cfW.block(fi,3*(-ri-1),1,3);
typename DerivedV::Scalar w0 = w.dot(b1);
typename DerivedV::Scalar w1 = w.dot(b2);
std::complex<typename DerivedV::Scalar> u(w0,w1);
tk*= u;
}
//collect sum
ck += tk;
}
Ck(ind) = ck;
ind ++;
}
}
}
template<typename DerivedV, typename DerivedF>
IGL_INLINE void igl::GeneralPolyVectorFieldFinder<DerivedV, DerivedF>::computek()
{
K.setZero(numE);
// For every non-border edge
for (unsigned eid=0; eid<numE; ++eid)
{
if (!isBorderEdge[eid])
{
int fid0 = E2F(eid,0);
int fid1 = E2F(eid,1);
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> N0 = FN.row(fid0);
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> N1 = FN.row(fid1);
// find common edge on triangle 0 and 1
int fid0_vc = -1;
int fid1_vc = -1;
for (unsigned i=0;i<3;++i)
{
if (F2E(fid0,i) == eid)
fid0_vc = i;
if (F2E(fid1,i) == eid)
fid1_vc = i;
}
assert(fid0_vc != -1);
assert(fid1_vc != -1);
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> common_edge = V.row(F(fid0,(fid0_vc+1)%3)) - V.row(F(fid0,fid0_vc));
common_edge.normalize();
// Map the two triangles in a new space where the common edge is the x axis and the N0 the z axis
Eigen::Matrix<typename DerivedV::Scalar, 3, 3> P;
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> o = V.row(F(fid0,fid0_vc));
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> tmp = -N0.cross(common_edge);
P << common_edge, tmp, N0;
// P.transposeInPlace();
Eigen::Matrix<typename DerivedV::Scalar, 3, 3> V0;
V0.row(0) = V.row(F(fid0,0)) -o;
V0.row(1) = V.row(F(fid0,1)) -o;
V0.row(2) = V.row(F(fid0,2)) -o;
V0 = (P*V0.transpose()).transpose();
// assert(V0(0,2) < 1e-10);
// assert(V0(1,2) < 1e-10);
// assert(V0(2,2) < 1e-10);
Eigen::Matrix<typename DerivedV::Scalar, 3, 3> V1;
V1.row(0) = V.row(F(fid1,0)) -o;
V1.row(1) = V.row(F(fid1,1)) -o;
V1.row(2) = V.row(F(fid1,2)) -o;
V1 = (P*V1.transpose()).transpose();
// assert(V1(fid1_vc,2) < 10e-10);
// assert(V1((fid1_vc+1)%3,2) < 10e-10);
// compute rotation R such that R * N1 = N0
// i.e. map both triangles to the same plane
double alpha = -atan2(V1((fid1_vc+2)%3,2),V1((fid1_vc+2)%3,1));
Eigen::Matrix<typename DerivedV::Scalar, 3, 3> R;
R << 1, 0, 0,
0, cos(alpha), -sin(alpha) ,
0, sin(alpha), cos(alpha);
V1 = (R*V1.transpose()).transpose();
// assert(V1(0,2) < 1e-10);
// assert(V1(1,2) < 1e-10);
// assert(V1(2,2) < 1e-10);
// measure the angle between the reference frames
// k_ij is the angle between the triangle on the left and the one on the right
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> ref0 = V0.row(1) - V0.row(0);
Eigen::Matrix<typename DerivedV::Scalar, 1, 3> ref1 = V1.row(1) - V1.row(0);
ref0.normalize();
ref1.normalize();
double ktemp = atan2(ref1(1),ref1(0)) - atan2(ref0(1),ref0(0));
// just to be sure, rotate ref0 using angle ktemp...
Eigen::Matrix<typename DerivedV::Scalar, 2, 2> R2;
R2 << cos(ktemp), -sin(ktemp), sin(ktemp), cos(ktemp);
Eigen::Matrix<typename DerivedV::Scalar, 1, 2> tmp1 = R2*(ref0.head(2)).transpose();
// assert(tmp1(0) - ref1(0) < 1e-10);
// assert(tmp1(1) - ref1(1) < 1e-10);
K[eid] = ktemp;
}
}
}
IGL_INLINE void igl::n_polyvector_general(const Eigen::MatrixXd &V,
const Eigen::MatrixXi &F,
const Eigen::VectorXi& b,
const Eigen::MatrixXd& bc,
const Eigen::VectorXi &I,
Eigen::MatrixXd &output)
{
Eigen::VectorXi isConstrained = Eigen::VectorXi::Constant(F.rows(),0);
Eigen::MatrixXd cfW = Eigen::MatrixXd::Constant(F.rows(),bc.cols(),0);
for(unsigned i=0; i<b.size();++i)
{
isConstrained(b(i)) = 1;
cfW.row(b(i)) << bc.row(i);
}
int n = I.rows();
igl::GeneralPolyVectorFieldFinder<Eigen::MatrixXd, Eigen::MatrixXi> pvff(V,F,n);
pvff.solve(isConstrained, cfW, I, output);
}
#ifdef IGL_STATIC_LIBRARY
// Explicit template specialization
#endif