CGAL users discussion list

[Sylvain Pion <>]

Sylvain Pion a écrit :
> Yang Liu a écrit :
> > Dear all,
> >
> > Recently I am using CGAL to compute 3D triangulation.
> > For some input data,  the 3D triangulation does not work.
> >
> > My simple test code is attached at the end of this email.
> >
> > I am using Microsoft Visual Studio 2008 and CGAL-3.3.1.
> > The CGAL library is recompiled under VS2008.
> >
> > My program always reports "Microsoft C++ exception: 
> > CGAL::Uncertain_conversion_exception at memory location ..." in debug 
> > mode.
>
> This issue has already been raised on the list.  Please have a look at
> the archive for details.  I have also added it to the FAQ:
> http://www.cgal.org/FAQ.html#uncertain_exception .
>
> Maybe there is a way to tell the debugger to ignore it.

Further investigation showed that there is actually an issue in CGAL 3.3.1.
Please use the replacement file attached for 
include/CGAL/number_utils_classes.h .

This should reduce/eliminate many uses of those internal exceptions.
As a bonus, it may give a speedup for some degenerate data sets.

--
Sylvain Pion
INRIA Sophia-Antipolis
Geometrica Project-Team
CGAL, http://cgal.org/
// Copyright (c) 1997  Utrecht University (The Netherlands),
// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz 
(Austria),
// and Tel-Aviv University (Israel).  All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the 
software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: 
svn+ssh://scm.gforge.inria.fr/svn/cgal/trunk/Algebraic_foundations/include/CGAL/number_utils_classes.h
 $
// $Id: number_utils_classes.h 44021 2008-07-08 07:03:41Z hemmer $
// 
//
// Author(s)     : Michael Hoffmann 
<>
//               : Michael Hemmer 
<>

// to be included by number_utils.h

#ifndef CGAL_NUMBER_UTILS_CLASSES_H
#define CGAL_NUMBER_UTILS_CLASSES_H 1

#include <CGAL/number_type_basic.h>
#include <algorithm>
#include <utility>

CGAL_BEGIN_NAMESPACE

/* Defines functors:
   - Is_zero
   - Is_one
   - Is_negative
   - Is_positive
   - Sgn
   - Abs
   - Compare
   - Square
   - Sqrt
   - Div
   - Gcd
   - To_double
   - To_interval
*/

template < class NT >
struct Is_negative : Real_embeddable_traits<NT>::Is_negative {};
template < class NT >
struct Is_positive : Real_embeddable_traits<NT>::Is_positive {};
template < class NT >
struct Abs : Real_embeddable_traits<NT>::Abs{};
template < class NT >
struct To_double : Real_embeddable_traits<NT>::To_double{};
template < class NT >
struct To_interval : Real_embeddable_traits<NT>::To_interval{};

// Sign would result in a name clash with enum.h
template < class NT >
struct Sgn : Real_embeddable_traits<NT>::Sign {};


template < class NT >
struct Square : Algebraic_structure_traits<NT>::Square{};
template < class NT >
struct Sqrt : Algebraic_structure_traits<NT>::Sqrt {};
template < class NT >
struct Div : Algebraic_structure_traits<NT>::Div{};
template < class NT >
struct Gcd : Algebraic_structure_traits<NT>::Gcd{};
template < class NT >
struct Is_one : Algebraic_structure_traits<NT>::Is_one {};

// This is due to the fact that Is_zero may be provided by 
// Algebraic_structure_traits as well as Real_embeddable_traits
// Of course it is not possible to derive from both since this 
// would cause an ambiguity. 
namespace CGALi{
template <class AST_Is_zero, class RET_Is_zero>
struct Is_zero_base : AST_Is_zero {} ;
template <class RET_Is_zero>
struct Is_zero_base <CGAL::Null_functor, RET_Is_zero >: RET_Is_zero {} ;
} // namespace CGALi
template < class NT >
struct Is_zero : 
  CGALi::Is_zero_base
  <typename Algebraic_structure_traits<NT>::Is_zero,
   typename Real_embeddable_traits<NT>::Is_zero>{}; 


// This is due to the fact that CGAL::Compare is used for other 
// non-realembeddable types as well.
// In this case we try to provide a default implementation
namespace CGALi {
template <class NT, class Compare> struct Compare_base: public Compare {};
template <class NT> struct Compare_base<NT,Null_functor>
  :public Binary_function< NT, NT, Comparison_result > {
  Comparison_result operator()( const NT& x, const NT& y) const
  {
    if (x < y) return SMALLER;
    if (x > y) return LARGER;
    CGAL_postcondition(x == y);
    return EQUAL;   
  }
};
} // namespace CGALi

template < class NT >
struct Compare
  :public CGALi::Compare_base
  <NT,typename Real_embeddable_traits<NT>::Compare>{};



CGAL_END_NAMESPACE

#endif // CGAL_NUMBER_UTILS_CLASSES_H

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