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// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2020 Oded Stein <oded.stein@columbia.edu>
//
// 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/.
#ifndef IGL_CR_VECTOR_LAPLACIAN_H
#define IGL_CR_VECTOR_LAPLACIAN_H
#include "igl_inline.h"
#include <Eigen/Core>
#include <Eigen/Sparse>
namespace igl
{
/// Computes the CR vector Laplacian matrix.
/// See Oded Stein, Max Wardetzky, Alec Jacobson, Eitan Grinspun, 2020.
/// "A Simple Discretization of the Vector Dirichlet Energy"
///
/// @param[in] V #V by 3 list of mesh vertex positions
/// @param[in] F #F by 3 list of mesh face indices into rows of V
/// @param[in] E #F by 3 a mapping from each halfedge to each edge
/// @param[in] oE #F by 3 the orientation (e.g., -1 or 1) of each halfedge
/// compared to the orientation of the actual edge, as computed with
/// orient_halfedges. will be computed if not provided.
/// @param[out] L 2*|HE| by 2*|HE| computed Laplacian matrix
template <typename DerivedV, typename DerivedF, typename DerivedE,
typename DerivedOE, typename ScalarL>
IGL_INLINE void
cr_vector_laplacian(
const Eigen::MatrixBase<DerivedV>& V,
const Eigen::MatrixBase<DerivedF>& F,
const Eigen::MatrixBase<DerivedE>& E,
const Eigen::MatrixBase<DerivedOE>& oE,
Eigen::SparseMatrix<ScalarL>& L);
/// \overload
///
/// \brief `E` and `oE` are computed and output.
template <typename DerivedV, typename DerivedF, typename DerivedE,
typename DerivedOE, typename ScalarL>
IGL_INLINE void
cr_vector_laplacian(
const Eigen::MatrixBase<DerivedV>& V,
const Eigen::MatrixBase<DerivedF>& F,
Eigen::PlainObjectBase<DerivedE>& E,
Eigen::PlainObjectBase<DerivedOE>& oE,
Eigen::SparseMatrix<ScalarL>& L);
/// \overload
/// \brief intrinsic version.
///
/// @param[in] l_sq #F by 3 list of squared edge lengths of each halfedge
/// @param[in] dA #F list of double areas
///
/// \fileinfo
template <typename DerivedF, typename DerivedL_sq, typename DeriveddA,
typename DerivedE, typename DerivedOE, typename ScalarL>
IGL_INLINE void
cr_vector_laplacian_intrinsic(
const Eigen::MatrixBase<DerivedF>& F,
const Eigen::MatrixBase<DerivedL_sq>& l_sq,
const Eigen::MatrixBase<DeriveddA>& dA,
const Eigen::MatrixBase<DerivedE>& E,
const Eigen::MatrixBase<DerivedOE>& oE,
Eigen::SparseMatrix<ScalarL>& L);
/// \overload
/// \fileinfo
template <typename DerivedF, typename DerivedL_sq, typename DerivedE,
typename DerivedOE, typename ScalarL>
IGL_INLINE void
cr_vector_laplacian_intrinsic(
const Eigen::MatrixBase<DerivedF>& F,
const Eigen::MatrixBase<DerivedL_sq>& l_sq,
const Eigen::MatrixBase<DerivedE>& E,
const Eigen::MatrixBase<DerivedOE>& oE,
Eigen::SparseMatrix<ScalarL>& L);
}
#ifndef IGL_STATIC_LIBRARY
# include "cr_vector_laplacian.cpp"
#endif
#endif