// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2020 Xiangyu Kong <xiangyu.kong@mail.utoronto.ca>
//
// 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_DIRECT_DELTA_MUSH_H
#define IGL_DIRECT_DELTA_MUSH_H

#include "igl_inline.h"

#include <Eigen/Core>
#include <Eigen/Sparse>
#include <Eigen/Geometry>
#include <vector>

namespace igl {
  /// Computes Direct Delta Mush Skinning (Variant 0) from "Direct Delta Mush
  /// Skinning and Variants"
  ///
  /// @param[in] V  #V by 3 list of rest pose vertex positions
  /// @param[in] T  #T list of bone pose transformations
  /// @param[in] Omega #V by #T*10 list of precomputated matrix values
  /// @param[out] U  #V by 3 list of output vertex positions
  template <
    typename DerivedV,
    typename DerivedOmega,
    typename DerivedU>
  IGL_INLINE void direct_delta_mush(
    const Eigen::MatrixBase<DerivedV> & V,
    const std::vector<
      Eigen::Affine3d, Eigen::aligned_allocator<Eigen::Affine3d>
    > & T, /* should eventually be templated more generally than double */
    const Eigen::MatrixBase<DerivedOmega> & Omega,
    Eigen::PlainObjectBase<DerivedU> & U);
  /// Precomputation for Direct Delta Mush Skinning.
  ///
  /// @param[in] V  #V by 3 list of rest pose vertex positions
  /// @param[in] F  #F by 3 list of triangle indices into rows of V
  /// @param[in] W  #V by #Edges list of weights
  /// @param[in] p  number of smoothing iterations
  /// @param[in] lambda  rotation smoothing step size
  /// @param[in] kappa   translation smoothness step size
  /// @param[in] alpha   translation smoothness blending weight
  /// @param[out] Omega  #V by #T*10 list of precomputated matrix values
  ///
  /// \fileinfo
  template <
    typename DerivedV,
    typename DerivedF,
    typename DerivedW,
    typename DerivedOmega>
  IGL_INLINE void direct_delta_mush_precomputation(
    const Eigen::MatrixBase<DerivedV> & V,
    const Eigen::MatrixBase<DerivedF> & F,
    const Eigen::MatrixBase<DerivedW> & W,
    const int p,
    const typename DerivedV::Scalar lambda,
    const typename DerivedV::Scalar kappa,
    const typename DerivedV::Scalar alpha,
    Eigen::PlainObjectBase<DerivedOmega> & Omega);
}

#ifndef IGL_STATIC_LIBRARY
#  include "direct_delta_mush.cpp"
#endif

#endif