47 lines
1.3 KiB
C++
47 lines
1.3 KiB
C++
// 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 "group_sum_matrix.h"
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template <typename T>
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IGL_INLINE void igl::group_sum_matrix(
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const Eigen::Matrix<int,Eigen::Dynamic,1> & G,
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const int k,
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Eigen::SparseMatrix<T>& A)
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{
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// number of vertices
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int n = G.rows();
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assert(k > G.maxCoeff());
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A.resize(k,n);
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// builds A such that A(i,j) = 1 where i corresponds to group i and j
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// corresponds to vertex j
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// Loop over vertices
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for(int j = 0;j<n;j++)
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{
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A.insert(G(j),j) = 1;
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}
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A.makeCompressed();
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}
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template <typename T>
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IGL_INLINE void igl::group_sum_matrix(
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const Eigen::Matrix<int,Eigen::Dynamic,1> & G,
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Eigen::SparseMatrix<T>& A)
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{
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return group_sum_matrix(G,G.maxCoeff()+1,A);
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}
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#ifdef IGL_STATIC_LIBRARY
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// Explicit template instantiation
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template void igl::group_sum_matrix<double>(Eigen::Matrix<int, -1, 1, 0, -1, 1> const&, int, Eigen::SparseMatrix<double, 0, int>&);
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template void igl::group_sum_matrix<double>(Eigen::Matrix<int, -1, 1, 0, -1, 1> const&, Eigen::SparseMatrix<double, 0, int>&);
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#endif
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