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[tang <>]

Dear all,

I am trying to write a program to merge coplanar facets. However, it crashed
there when running 'coplanar' after op=53. Could anyone help me to take a
look at the code to tell me what problem in the code?
aa0.off <http://cgal-discuss.949826.n4.nabble.com/file/n4657929/aa0.off>  

Thanks,
Zhanghong Tang

The code:

#include <vector>
#include <iostream>
#include <istream>
#include <fstream>  

#include <CGAL/Exact_predicates_exact_constructions_kernel.h>
#include <CGAL/Nef_polyhedron_3.h>
#include <CGAL/IO/Polyhedron_iostream.h>
#include <CGAL/IO/Nef_polyhedron_iostream_3.h>  
#include <CGAL/Polyhedron_3.h>

typedef CGAL::Exact_predicates_exact_constructions_kernel   Kernel;

typedef Kernel::Point_3                                     Point;
typedef Kernel::Plane_3                                     Plane;

typedef CGAL::Polyhedron_3<Kernel>                                            
                                                          Polyhedron;
typedef CGAL::Nef_polyhedron_3<Kernel>                                        
                                          Nef_polyhedron;
typedef Polyhedron::Halfedge_handle                                           
                                                          Halfedge_handle;
typedef Polyhedron::Halfedge_iterator                                         
                                                  Halfedge_iterator;
typedef Nef_polyhedron::Vector_3                                              
                                                                  Vector_3;

bool coplanar(Halfedge_handle &h1, Halfedge_handle &h2,double eps)
{
        Vector_3 n1 = CGAL::cross_product(
    h1->next()->vertex()->point() - h1->vertex()->point(),
    h1->next()->next()->vertex()->point()- h1->next()->vertex()->point());
        n1=n1/Kernel::FT(CGAL::sqrt(CGAL::to_double(n1.squared_length()))); 
        Vector_3 n2 = CGAL::cross_product(
    h2->next()->vertex()->point() - h2->vertex()->point(),
    h2->next()->next()->vertex()->point()- h2->next()->vertex()->point());
        n2=n2/Kernel::FT(CGAL::sqrt(CGAL::to_double(n2.squared_length()))); 
        double len1 = CGAL::to_double((n1 - n2).squared_length());
        double len2 = CGAL::to_double((n1 + n2).squared_length());
        if(len1>=eps && len2>=eps)
                return false;
        else
                return true;
}


void MergeCoplanarFacet(Polyhedron &p,double normalmin)
{
        /// this function is used to merge coplanar facets
        /// Zhanghong Tang @ 08/10/2013
        double eps=normalmin*normalmin;
        int op=0, debugnum=0;
  while (true)
  {
    bool merged = false;
    for (Halfedge_iterator he = p.halfedges_begin();he != p.halfedges_end();
he++)
    {
                        Polyhedron::Halfedge_handle ohe = he->opposite();
                        if (coplanar(he, ohe,eps))
                        {
                                p.join_facet(he);
                                op++;
                                if(op>=debugnum)
                                {
                                        printf("op = %d\n",op);
                                }
                                merged = true;
                                break;
                        }
    }
    if (!merged)
      break;
  }
}

int main(int argc, char * argv[])
{
        Polyhedron *p = new Polyhedron;
  std::ifstream stream("aa0.off");
  stream >> *p;
        MergeCoplanarFacet(*p,1.0e-5);

  return 0;
}




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