slim.h

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/* SPDX-FileCopyrightText: 2016 Michael Rabinovich
 *                         2023 Blender Authors
 *
 * SPDX-License-Identifier: MPL-2.0 */
 
#pragma once
 
#include <Eigen/Dense>
#include <Eigen/Sparse>
 
#include <stdexcept>
 
namespace slim {
 
class SlimFailedException : public std::runtime_error {
 public:
  SlimFailedException() : std::runtime_error("Slim operation failed") {}
};
 
/* Compute a SLIM map as derived in "Scalable Locally Injective Maps" [Rabinovich et al. 2016].. */
struct SLIMData {
  bool valid = true;
 
  /* Input. */
  Eigen::MatrixXd V; /* #V by 3 list of mesh vertex positions. */
  Eigen::MatrixXi F; /* #F by 3/3 list of mesh faces (triangles). */
  enum SLIM_ENERGY {
    ARAP,
    LOG_ARAP,
    SYMMETRIC_DIRICHLET,
    CONFORMAL,
    EXP_CONFORMAL,
    EXP_SYMMETRIC_DIRICHLET
  };
  SLIM_ENERGY slim_energy;
 
  /* Optional Input. */
  /* Soft constraints. */
  Eigen::VectorXi b;
  Eigen::MatrixXd bc;
  double soft_const_p;
 
  double exp_factor;        /* Used for exponential energies, ignored otherwise. */
  bool mesh_improvement_3d; /* Only supported for 3d. */
 
  int reflection_mode;
  bool skipInitialization = false;
  bool validPreInitialization = false;
  double expectedSurfaceAreaOfResultingMap = 0;
 
  /* Output. */
  Eigen::MatrixXd V_o; /* #V by dim list of mesh vertex positions (dim = 2 for parametrization, 3
                          otherwise). */
  Eigen::MatrixXd
      oldUVs; /* #V by dim list of mesh vertex positions (dim = 2 for parametrization,. */
              /* 3 otherwise). */
 
  /* Weight-map for weighted parameterization. */
  bool withWeightedParameterization;
  Eigen::VectorXf weightmap;
  Eigen::VectorXf weightPerFaceMap;
  double weightInfluence;
  double globalScaleInvarianceFactor = 1.0;
 
  double energy; /* Objective value. */
 
  /* Internal. */
  Eigen::VectorXd M;
  double mesh_area;
  double avg_edge_length;
  int v_num;
  int f_num;
  double proximal_p;
 
  Eigen::VectorXd WGL_M;
  Eigen::VectorXd rhs;
  Eigen::MatrixXd Ri, Ji;
  Eigen::VectorXd W_11;
  Eigen::VectorXd W_12;
  Eigen::VectorXd W_13;
  Eigen::VectorXd W_21;
  Eigen::VectorXd W_22;
  Eigen::VectorXd W_23;
  Eigen::VectorXd W_31;
  Eigen::VectorXd W_32;
  Eigen::VectorXd W_33;
  Eigen::SparseMatrix<double> Dx, Dy, Dz;
  int f_n, v_n;
  bool first_solve;
  bool has_pre_calc = false;
  int dim;
};
 
/* Compute necessary information to start using SLIM
 * Inputs:
 *      V           #V by 3 list of mesh vertex positions
 *      F           #F by 3/3 list of mesh faces (triangles)
 *    b           list of boundary indices into V
 *    bc          #b by dim list of boundary conditions
 *    soft_p      Soft penalty factor (can be zero)
 *    slim_energy Energy to minimize
 */
void slim_precompute(Eigen::MatrixXd &V,
                     Eigen::MatrixXi &F,
                     Eigen::MatrixXd &V_init,
                     SLIMData &data,
                     SLIMData::SLIM_ENERGY slim_energy,
                     Eigen::VectorXi &b,
                     Eigen::MatrixXd &bc,
                     double soft_p);
 
/* Run iter_num iterations of SLIM
 * Outputs:
 *    V_o (in SLIMData): #V by dim list of mesh vertex positions
 */
Eigen::MatrixXd slim_solve(SLIMData &data, int iter_num);
 
}  // namespace slim