CGAL users discussion list

[Peter Hachenberger <>]

Hi

that's a rendering problem of geomview. The CGAL computations are
correct. Use the viewer of Nef_polyhedron_3. There will be no additional
facets in this viewer.

Peter

On Sun, 2006-11-26 at 19:55 +0100, 

 wrote:
> Hi,
> 
> I have 2 additional facets with this very simple program:
> 
> /*********************** CUT HERE *************************/
> #include "CGAL/basic.h" // Manuel page 7
> #include <CGAL/Gmpz.h>
> #include <CGAL/Exact_predicates_exact_constructions_kernel_with_sqrt.h>
> #include <CGAL/Polyhedron_3.h>
> #include <CGAL/Convex_hull_traits_3.h>
> #include <CGAL/convex_hull_3.h>
> #include <CGAL/Vector_3.h>
> #include <CGAL/IO/Geomview_stream.h>
> #include <CGAL/IO/Triangulation_geomview_ostream_3.h>
> #include <CGAL/IO/Polyhedron_geomview_ostream.h>
> #include <vector>
> 
> #include <CGAL/Nef_polyhedron_3.h>
> 
> typedef CGAL::Exact_predicates_exact_constructions_kernel_with_sqrt Kernel;
> typedef Kernel::RT RT;
> 
> typedef CGAL::Nef_polyhedron_3<Kernel> Poly3D;
> typedef CGAL::Point_3<Kernel>          Point3D;
> 
> Poly3D MakeVol(Point3D a, Point3D b)
> {
>   CGAL::Iso_cuboid_3<Kernel> cube(a,b);
>   CGAL::Object ch_object;
>   CGAL::Polyhedron_3<Kernel> p0;
>   std::vector<Point3D> points;
> 
>   p0.clear();
>   points.clear();
>   for(int i=0;i<8;i++) points.push_back(cube.vertex(i));
>     
>   CGAL::convex_hull_3(points.begin(), points.end(), ch_object);
> 
>   if(CGAL::assign(p0, ch_object)!=true) {
>     std::cout << "pn: convex hull error!" << std::endl;
>     return(Poly3D());
>   }
>   return(Poly3D(p0));
> }
> 
> 
> int main(int argc, char argv[])
> {
>   Poly3D b1=MakeVol(Point3D(1,1,1), Point3D(10,10,10));
>   Poly3D b2=MakeVol(Point3D(1,1,9), Point3D(20,20,20));
>   
>   Poly3D b3=b1.join(b2);
>   
>   CGAL::Geomview_stream gv(CGAL::Bbox_3(-100, -100, -100, 600, 600, 600));
>   gv.set_line_width(4);
>   gv.set_bg_color(CGAL::Color(0, 200, 200));
>   gv.clear();
>   
>   CGAL::Polyhedron_3<Kernel> p0;
>   b3.convert_to_Polyhedron(p0);
>   gv << p0;
>   
>   std::cout << "Enter a key to finish" << std::endl;
>   char ch;
>   std::cin >> ch;
> 
> }
> /*********************** CUT HERE *************************/
> I use: gcc 4.1.2 (same problem with gcc 4.0.2)
> geomview-1.8.2-rc9
> gmp-4.2.1
> mpfr-2.2.0
> CGAL-3.2.1
> 
> All of them home compilated.
> 
> The 2 additional facets seems to be generated when the 2nd Nef_polyhedron_2 
> is in the corner of the first.
> 
> Does anyone has the same problem, or a solution?
> 
> Thanks for help.
>