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[Joe C <>]

Happy New Year to CGAL community!

I am picking up an old thread from my last email in the hope that someone from GGAL can help. More tests show some IO error too when I use the following code snippet to read the attched .off file to a polyhedron

Polyhedron p1;
std::ifstream OpenFile("intersect_poly_1.off");
OpenFile >> p1;

The debug information shows that something is wrong in Polyhedron_scan_OFF.h. specifically, line 100:

if( ! m_in || B.error() || no < 3) {
            if ( scanner.verbose()) {
                std::cerr << " " << std::endl;
                std::cerr << "Polyhedron_scan_OFF<Traits>::" << std::endl;
                std::cerr << "operator()(): input error: facet " << i
                     << " has less than 3 vertices." << std::endl;
            }
            B.rollback();
            m_in.clear( std::ios::badbit);
            return;
        }

I have been struggling for some time, really hope that someone from CGAL could provide help or at least give some hints on this error.

Thanks.
Joe

On Mon, Dec 21, 2009 at 1:21 PM, Joe C <> wrote:

I also tried this using latest CGAL 3.5. This time I got error when converting Polyhedron_1 to Nef_polyhedron_3:

Error !!!!!!!!!!!!!!!!!!!!!!!
Error !!!!!!!!!!!!!!!!!!!!!!!
Error !!!!!!!!!!!!!!!!!!!!!!!
CGAL error: assertion violation!
_expression_ : pe_prev->is_border() || !pe_prev->facet()->plane().is_degenerate()
File       : E:\CGAL-3.5\Include\CGAL/Nef_3/polyhedron
_3_to_nef_3.h
Line       : 217
Explanation:
Refer to the bug-reporting instructions at http://www.cgal.org/bug_report.html

Before converting, I checked Polyhedron_1 which was valid and closed.

On Mon, Dec 21, 2009 at 11:14 AM, Joe C <> wrote:

Hi Laure,

Thanks for your reply. But it did not work for me... The polyhedra are already triangulated, i. e. they are both pure triangles. Maybe it is a bug in Nef_polyhedron_3?

Joe

On Mon, Dec 21, 2009 at 8:42 AM, Laure Guicherd <> wrote:

Hi Joe,

I had the same problem a few months ago, did you try triangulating your polyhedrons before converting them to nef ? This solved it for me :)

Good luck,
Laure

Joe C wrote:

I still could not find solution. Any other requirements on polyhedron besides "closed" and "valid" to make sure the intersection go through?

Joe

On Fri, Dec 18, 2009 at 2:24 PM, Joe C < <mailto:>> wrote:

   Hi All,

   Intersection of Nef_polyhedron_3 failed When I tried to compute
   the intersection of two polyhedra (see attached files). I am using
   Exact_predicates_exact_constructions_kernel. Both of the polyhedra
   are closed and valid and have been converted to Nef_polyhedron_3
   successfully. It failed when executing the intersection of
   converted Nef_polyhedron_3. The version of CGAL is 3.4 with Visual
   Studio 2008 (SP1) and Win XP Professional.

   Anyone can help with this?

   Thanks.
   Joe

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Attachment: intersect_poly_1.off
Description: Binary data