46 lines
1.4 KiB
C++
46 lines
1.4 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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#ifndef IGL_GROUP_SUM_MATRIX_H
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#define IGL_GROUP_SUM_MATRIX_H
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#include "igl_inline.h"
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#include <Eigen/Dense>
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#include <Eigen/Sparse>
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namespace igl
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{
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// GROUP_SUM_MATRIX Builds a matrix A such that A*V computes the sum of
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// vertices in each group specified by G
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//
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// group_sum_matrix(G,k,A);
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//
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// Templates:
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// T should be a eigen sparse matrix primitive type like int or double
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// Inputs:
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// G #V list of group indices (0 to k-1) for each vertex, such that vertex i
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// is assigned to group G(i)
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// k #groups, good choice is max(G)+1
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// Outputs:
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// A #groups by #V sparse matrix such that A*V = group_sums
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//
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template <typename T>
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IGL_INLINE void 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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// Wrapper with k = max(G)+1
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template <typename T>
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IGL_INLINE void 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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#ifndef IGL_STATIC_LIBRARY
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# include "group_sum_matrix.cpp"
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#endif
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#endif
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