89 lines
3.3 KiB
C++
89 lines
3.3 KiB
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) 2013 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 "cotmatrix.h"
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#include <vector>
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// For error printing
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#include <cstdio>
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#include "cotmatrix_entries.h"
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// Bug in unsupported/Eigen/SparseExtra needs iostream first
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#include <iostream>
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template <typename DerivedV, typename DerivedF, typename Scalar>
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IGL_INLINE void igl::cotmatrix(
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const Eigen::MatrixBase<DerivedV> & V,
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const Eigen::MatrixBase<DerivedF> & F,
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Eigen::SparseMatrix<Scalar>& L)
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{
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using namespace Eigen;
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using namespace std;
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L.resize(V.rows(),V.rows());
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Matrix<int,Dynamic,2> edges;
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int simplex_size = F.cols();
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// 3 for triangles, 4 for tets
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assert(simplex_size == 3 || simplex_size == 4);
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if(simplex_size == 3)
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{
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// This is important! it could decrease the comptuation time by a factor of 2
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// Laplacian for a closed 2d manifold mesh will have on average 7 entries per
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// row
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L.reserve(10*V.rows());
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edges.resize(3,2);
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edges <<
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1,2,
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2,0,
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0,1;
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}else if(simplex_size == 4)
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{
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L.reserve(17*V.rows());
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edges.resize(6,2);
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edges <<
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1,2,
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2,0,
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0,1,
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3,0,
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3,1,
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3,2;
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}else
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{
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return;
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}
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// Gather cotangents
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Matrix<Scalar,Dynamic,Dynamic> C;
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cotmatrix_entries(V,F,C);
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vector<Triplet<Scalar> > IJV;
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IJV.reserve(F.rows()*edges.rows()*4);
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// Loop over triangles
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for(int i = 0; i < F.rows(); i++)
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{
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// loop over edges of element
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for(int e = 0;e<edges.rows();e++)
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{
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int source = F(i,edges(e,0));
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int dest = F(i,edges(e,1));
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IJV.push_back(Triplet<Scalar>(source,dest,C(i,e)));
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IJV.push_back(Triplet<Scalar>(dest,source,C(i,e)));
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IJV.push_back(Triplet<Scalar>(source,source,-C(i,e)));
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IJV.push_back(Triplet<Scalar>(dest,dest,-C(i,e)));
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}
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}
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L.setFromTriplets(IJV.begin(),IJV.end());
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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 void igl::cotmatrix<Eigen::Matrix<double, -1, -1, 1, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, double>(Eigen::MatrixBase<Eigen::Matrix<double, -1, -1, 1, -1, -1> > const&, Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::SparseMatrix<double, 0, int>&);
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template void igl::cotmatrix<Eigen::Matrix<double, -1, 3, 0, -1, 3>, Eigen::Matrix<int, -1, 4, 0, -1, 4>, double>(Eigen::MatrixBase<Eigen::Matrix<double, -1, 3, 0, -1, 3> > const&, Eigen::MatrixBase<Eigen::Matrix<int, -1, 4, 0, -1, 4> > const&, Eigen::SparseMatrix<double, 0, int>&);
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template void igl::cotmatrix<Eigen::Matrix<double, -1, 3, 0, -1, 3>, Eigen::Matrix<int, -1, 3, 0, -1, 3>, double>(Eigen::MatrixBase<Eigen::Matrix<double, -1, 3, 0, -1, 3> > const&, Eigen::MatrixBase<Eigen::Matrix<int, -1, 3, 0, -1, 3> > const&, Eigen::SparseMatrix<double, 0, int>&);
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template void igl::cotmatrix<Eigen::Matrix<double, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1>, double>(Eigen::MatrixBase<Eigen::Matrix<double, -1, -1, 0, -1, -1> > const&, Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::SparseMatrix<double, 0, int>&);
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#endif
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