CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Would be great if you could post a minimal and complete example
showing the problem. No one can guess for example what kernel you are using.

S.


sara123 wrote:
> this function in my program should calculate the total area of these polygons
> after union calculation:
>
> the input factor to this function is a vector of polygon_2 and the output is
> a number.
>
> RT Union(std::vector<Polygon_2> pol_vector)
> {//
>   std::vector<Polygon_2>::iterator mit;
>   //G_Polygon_set_2 S;
>   Polygon_set_2 S;
>   RT area_hole=0.0;
>   RT sum_area_hole=0.0;
>   RT area=0.0;
>   RT sum_area=0, area_bound;
>   Polygon_2 A;
>
> for (mit = pol_vector.begin(); mit != pol_vector.end(); ++mit)
> {
>         A=*mit;
>         S.join (A);
> }
> //S.join(pol_vector.begin(),pol_vector.end());
>   std::list<Polygon_with_holes_2> res;
>   std::list<Polygon_with_holes_2>::const_iterator it;
>   std::list<Polygon_with_holes_2> my;
>   Polygon_with_holes_2 mes;
>   CGAL::Polygon_with_holes_2<K>::Hole_const_iterator hit;
>
>   //std::cout << "The result contains " << S.number_of_polygons_with_holes()
> << " components:" << std::endl;
>   
>
> S.polygons_with_holes (std::back_inserter (res));
>   for (it = res.begin(); it != res.end(); ++it) 
>   {///
>   std::cout << "--> "<<*it<<std::endl;
>   mes=*it;
>   sum_area_hole=0;
>   for (hit=mes.holes_begin(); hit!=mes.holes_end(); ++hit)
>   {//// 
> 	 area_hole=(*hit).area();
>          sum_area_hole=area_hole+sum_area_hole;
>         /*std::cout <<"sum_area_hole="<<sum_area_hole<<std::endl;*/
>   }////
>          area_bound=(mes.outer_boundary()).area();
>          area=area_bound + sum_area_hole;//sum_area_hole manfi mibashad
>          sum_area=sum_area+area;
>          /*std::cout <<"area="<<area<<std::endl;
> 	 std::cout <<"sum_area="<<sum_area<<std::endl;*/ 
>   }///
> return sum_area;
> }//
>
>
> the error is in calculating the area of two polygons that are RED and BLUE
> in picture:
> http://cgal-discuss.949826.n4.nabble.com/file/n3249230/22222.bmp