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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"
//
// Inputs:
// V, F: input mesh
// E: a mapping from each halfedge to each edge, as computed with
// orient_halfedges.
// will be computed if not provided.
// oE: the orientation of each halfedge compared to the orientation of the
// actual edge, as computed with orient_halfedges.
// will be computed if not provided.
//
// Outputs:
// L: computed Laplacian matrix
// E, oE: these are computed if they are not present, as described above
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);
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);
// Version that uses intrinsic quantities as input
//
// Inputs:
// F: input mesh connectivity
// l_sq: squared edge lengths of each halfedge
// dA: double area of each face
// E: a mapping from each halfedge to each edge.
// oE: the orientation of each halfedge compared to the orientation of the
// actual edge.
//
// Outputs:
// L: computed Laplacian matrix
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);
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);
}
#ifndef IGL_STATIC_LIBRARY
# include "cr_vector_laplacian.cpp"
#endif
#endif