libigl_Martin/include/igl/boundary_facets.cpp

// This file is part of libigl, a simple c++ geometry processing library.
//
// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
//
// 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/.
#include "boundary_facets.h"
#include "face_occurrences.h"
#include "list_to_matrix.h"
#include "matrix_to_list.h"
#include "sort.h"
#include "unique_rows.h"
#include "accumarray.h"
#include "slice_mask.h"

#include <Eigen/Core>

#include <map>
#include <iostream>

template <
  typename DerivedT, 
  typename DerivedF,
  typename DerivedJ,
  typename DerivedK>
IGL_INLINE void igl::boundary_facets(
  const Eigen::MatrixBase<DerivedT>& T,
  Eigen::PlainObjectBase<DerivedF>& F,
  Eigen::PlainObjectBase<DerivedJ>& J,
  Eigen::PlainObjectBase<DerivedK>& K)
{
  const int simplex_size = T.cols();
  // Handle boring base case
  if(T.rows() == 0)
  {
    F.resize(0,simplex_size-1);
    J.resize(0,1);
    K.resize(0,1);
    return;
  }
  // Get a list of all facets
  DerivedF allF(T.rows()*simplex_size,simplex_size-1);
  // Gather faces (e.g., loop over tets)
  for(int i = 0; i< (int)T.rows();i++)
  {
    switch(simplex_size)
    {
      case 4:
        // get face in correct order
        allF(i*simplex_size+0,0) = T(i,1);
        allF(i*simplex_size+0,1) = T(i,3);
        allF(i*simplex_size+0,2) = T(i,2);
        // get face in correct order
        allF(i*simplex_size+1,0) = T(i,0);
        allF(i*simplex_size+1,1) = T(i,2);
        allF(i*simplex_size+1,2) = T(i,3);
        // get face in correct order
        allF(i*simplex_size+2,0) = T(i,0);
        allF(i*simplex_size+2,1) = T(i,3);
        allF(i*simplex_size+2,2) = T(i,1);
        // get face in correct order
        allF(i*simplex_size+3,0) = T(i,0);
        allF(i*simplex_size+3,1) = T(i,1);
        allF(i*simplex_size+3,2) = T(i,2);
        break;
      case 3:
        allF(i*simplex_size+0,0) = T(i,1);
        allF(i*simplex_size+0,1) = T(i,2);
        allF(i*simplex_size+1,0) = T(i,2);
        allF(i*simplex_size+1,1) = T(i,0);
        allF(i*simplex_size+2,0) = T(i,0);
        allF(i*simplex_size+2,1) = T(i,1);
        break;
    }
  }
  DerivedF sortedF;
  igl::sort(allF,2,true,sortedF);
  Eigen::VectorXi m,n;
  {
    DerivedF _1;
    igl::unique_rows(sortedF,_1,m,n);
  }
  Eigen::VectorXi C;
  igl::accumarray(n,1,C);
  const int ones = (C.array()==1).count();
  // Resize output to fit number of non-twos
  F.resize(ones, allF.cols());
  J.resize(F.rows(),1);
  K.resize(F.rows(),1);
  int k = 0;
  for(int c = 0;c< (int)C.size();c++)
  {
    if(C(c) == 1)
    {
      const int i = m(c);
      assert(k<(int)F.rows());
      F.row(k) = allF.row(i);
      J(k) = i/simplex_size;
      K(k) = i%simplex_size;
      k++;
    }
  }
  assert(k==(int)F.rows());
}

template <typename DerivedT, typename DerivedF>
IGL_INLINE void igl::boundary_facets(
  const Eigen::MatrixBase<DerivedT>& T,
  Eigen::PlainObjectBase<DerivedF>& F)
{
  Eigen::VectorXi J,K;
  return boundary_facets(T,F,J,K);
}

template <typename DerivedT, typename Ret>
Ret igl::boundary_facets(
  const Eigen::MatrixBase<DerivedT>& T)
{
  Ret F;
  igl::boundary_facets(T,F);
  return F;
}

template <typename IntegerT, typename IntegerF>
IGL_INLINE void igl::boundary_facets(
  const std::vector<std::vector<IntegerT> > & T,
  std::vector<std::vector<IntegerF> > & F)
{
  // Kept for legacy reasons. Could probably just delete.
  using namespace std;

  if(T.size() == 0)
  {
    F.clear();
    return;
  }

  int simplex_size = T[0].size();
  // Get a list of all faces
  vector<vector<IntegerF> > allF(
    T.size()*simplex_size,
    vector<IntegerF>(simplex_size-1));

  // Gather faces, loop over tets
  for(int i = 0; i< (int)T.size();i++)
  {
    assert((int)T[i].size() == simplex_size);
    switch(simplex_size)
    {
      case 4:
        // get face in correct order
        allF[i*simplex_size+0][0] = T[i][1];
        allF[i*simplex_size+0][1] = T[i][3];
        allF[i*simplex_size+0][2] = T[i][2];
        // get face in correct order
        allF[i*simplex_size+1][0] = T[i][0];
        allF[i*simplex_size+1][1] = T[i][2];
        allF[i*simplex_size+1][2] = T[i][3];
        // get face in correct order
        allF[i*simplex_size+2][0] = T[i][0];
        allF[i*simplex_size+2][1] = T[i][3];
        allF[i*simplex_size+2][2] = T[i][1];
        // get face in correct order
        allF[i*simplex_size+3][0] = T[i][0];
        allF[i*simplex_size+3][1] = T[i][1];
        allF[i*simplex_size+3][2] = T[i][2];
        break;
      case 3:
        allF[i*simplex_size+0][0] = T[i][1];
        allF[i*simplex_size+0][1] = T[i][2];
        allF[i*simplex_size+1][0] = T[i][2];
        allF[i*simplex_size+1][1] = T[i][0];
        allF[i*simplex_size+2][0] = T[i][0];
        allF[i*simplex_size+2][1] = T[i][1];
        break;
    }
  }

  // Counts
  vector<int> C;
  face_occurrences(allF,C);

  // Q: Why not just count the number of ones?
  // A: because we are including non-manifold edges as boundary edges
  int twos = (int) count(C.begin(),C.end(),2);
  //int ones = (int) count(C.begin(),C.end(),1);
  // Resize output to fit number of ones
  F.resize(allF.size() - twos);
  //F.resize(ones);
  int k = 0;
  for(int i = 0;i< (int)allF.size();i++)
  {
    if(C[i] != 2)
    {
      assert(k<(int)F.size());
      F[k] = allF[i];
      k++;
    }
  }
  assert(k==(int)F.size());
  //if(k != F.size())
  //{
  //  printf("%d =? %d\n",k,F.size());
  //}

}


#ifdef IGL_STATIC_LIBRARY
// Explicit template instantiation
// generated by autoexplicit.sh
template void igl::boundary_facets<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> >&);
// generated by autoexplicit.sh
template void igl::boundary_facets<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<unsigned int, -1, 3, 1, -1, 3> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<unsigned int, -1, 3, 1, -1, 3> >&);
// generated by autoexplicit.sh
template void igl::boundary_facets<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, 3, 0, -1, 3> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, 3, 0, -1, 3> >&);
template void igl::boundary_facets<int, int>(std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > > const&, std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > >&);
//template Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > igl::boundary_facets(Eigen::PlainObjectBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&);
template Eigen::Matrix<int, -1, -1, 0, -1, -1> igl::boundary_facets<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, -1, 0, -1, -1> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&);
template void igl::boundary_facets<Eigen::Matrix<int, -1, -1, 0, -1, -1>, Eigen::Matrix<int, -1, 3, 1, -1, 3> >(Eigen::MatrixBase<Eigen::Matrix<int, -1, -1, 0, -1, -1> > const&, Eigen::PlainObjectBase<Eigen::Matrix<int, -1, 3, 1, -1, 3> >&);
#endif