libigl_Martin/include/igl/embree/orient_outward_ao.cpp

#include "orient_outward_ao.h"
#include "../per_face_normals.h"
#include "../barycenter.h"
#include "../doublearea.h"
#include "../matlab_format.h"
#include "ambient_occlusion.h"
#include <iostream>
#include <random>

template <
  typename DerivedV, 
  typename DerivedF, 
  typename DerivedC, 
  typename PointMatrixType,
  typename FaceMatrixType,
  typename RowVector3,
  typename DerivedFF, 
  typename DerivedI>
IGL_INLINE void igl::orient_outward_ao(
  const Eigen::PlainObjectBase<DerivedV> & V,
  const Eigen::PlainObjectBase<DerivedF> & F,
  const Eigen::PlainObjectBase<DerivedC> & C,
  const igl::EmbreeIntersector<PointMatrixType,FaceMatrixType,RowVector3> & ei,
  const int num_samples,
  Eigen::PlainObjectBase<DerivedFF> & FF,
  Eigen::PlainObjectBase<DerivedI> & I)
{
  using namespace Eigen;
  using namespace std;
  assert(C.rows() == F.rows());
  assert(F.cols() == 3);
  assert(V.cols() == 3);

  // number of faces
  const int m = F.rows();
  // number of patches
  const int num_cc = C.maxCoeff()+1;
  I.resize(num_cc);
  if(&FF != &F)
  {
    FF = F;
  }
  PlainObjectBase<DerivedV> N;
  Matrix<typename DerivedV::Scalar,Dynamic,1> A;
  per_face_normals(V,F,N);
  doublearea(V,F,A);
  double minarea = A.minCoeff();
  mt19937 engine;
  engine.seed(time(0));
  Matrix<int, Dynamic, 1> A_int = (A * 100.0 / minarea).cast<int>();
  auto ddist_func = [&] (double i) { return A_int(static_cast<int>(i)); };
  discrete_distribution<int> ddist(m, 0, m, ddist_func);      // simple ctor of (Iter, Iter) not provided by the stupid VC11 impl...
  uniform_real_distribution<double> rdist;
  Matrix<int, Dynamic, 1> C_occlude_count;        // +1 when front ray is occluded, -1 when back ray is occluded
  C_occlude_count.setZero(m, 1);
//#pragma omp parallel for
  for (int i = 0; i < num_samples; ++i)
  {
    int f = ddist(engine);   // select face with probability proportional to face area
    double t0 = rdist(engine);
    double t1 = rdist(engine);
    double t2 = rdist(engine);
    double t_sum = t0 + t1 + t2;
    t0 /= t_sum;
    t1 /= t_sum;
    t2 /= t_sum;
    RowVector3d p = t0 * V.row(F(f,0)) + t1 * V.row(F(f,1)) + t1 * V.row(F(f,2));
    RowVector3d n = N.row(f);
    bool is_backside = rdist(engine) < 0.5;
    if (is_backside)
    {
        n *= -1;
    }
    Matrix<typename DerivedV::Scalar,Dynamic,1> S;
    ambient_occlusion(ei, p, n, 1, S);
    if (S(0) > 0)
    {
      C_occlude_count(C(f)) += is_backside ? -1 : 1;
    }

  }
  for(int c = 0;c<num_cc;c++)
  {
    I(c) = C_occlude_count(c) > 0;
  }
  // flip according to I
  for(int f = 0;f<m;f++)
  {
    if(I(C(f)))
    {
      FF.row(f) = FF.row(f).reverse().eval();
    }
  }
}

// EmbreeIntersector generated on the fly
template <
  typename DerivedV, 
  typename DerivedF, 
  typename DerivedC, 
  typename DerivedFF, 
  typename DerivedI>
IGL_INLINE void igl::orient_outward_ao(
  const Eigen::PlainObjectBase<DerivedV> & V,
  const Eigen::PlainObjectBase<DerivedF> & F,
  const Eigen::PlainObjectBase<DerivedC> & C,
  const int num_samples,
  Eigen::PlainObjectBase<DerivedFF> & FF,
  Eigen::PlainObjectBase<DerivedI> & I)
{
  using namespace igl;
  using namespace Eigen;
  EmbreeIntersector<
    PlainObjectBase<DerivedV>,
    PlainObjectBase<DerivedF>,
    Matrix<typename DerivedV::Scalar,3,1> > ei(V,F);
  return orient_outward_ao(V, F, C, ei, num_samples, FF, I);
}