CGAL users discussion list

[Francesc Vila <>]

When I change the kernel type, I obtain compilation errors:

d:\cgal-3.6.1\include\cgal\compute_outer_frame_margin.h(113) : error 
C2664: 'boost::optional<T>::optional(boost::none_t)' : cannot convert 
parameter 1 from 'boost::optional<T>' to 'boost::none_t'
        with
        [
            T=KFT
        ]
        and
        [
            T=CGAL::Lazy_exact_nt<CGAL::Gmpq>
        ]
        No user-defined-conversion operator available that can perform 
this conversion, or the operator cannot be called
        d:\cgal-3.6.1\include\cgal\create_offset_polygons_2.h(92) : see 
reference to function template instantiation 'boost::optional<T> 
CGAL::compute_outer_frame_margin<PointIterator,FT>(ForwardPointIterator,ForwardPointIterator,FT)' 
being compiled
        with
        [
            T=KFT,
            
PointIterator=std::_Vector_iterator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>,std::allocator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>>>,
            FT=double,
            
ForwardPointIterator=std::_Vector_iterator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>,std::allocator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>>>
        ]
        d:\cgal-3.6.1\include\cgal\create_offset_polygons_2.h(319) : 
see reference to function template instantiation 'boost::shared_ptr<T> 
CGAL::CGAL_SS_i::create_partial_exterior_straight_skeleton_2<FT,std::_Vector_iterator<_Ty,_Alloc>,SsK>(const 
FT &,PointIterator,PointIterator,const K &)' being compiled
        with
        [
            
T=CGAL::Straight_skeleton_2<CGAL::Exact_predicates_inexact_constructions_kernel>,
            FT=double,
            
_Ty=CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>,
            
_Alloc=std::allocator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>>,
            SsK=CGAL::Filtered_kernel<CGAL::Simple_cartesian<double>>,
            
PointIterator=std::_Vector_iterator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>,std::allocator<CGAL::Point_2<CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>>>>,
            K=CGAL::Filtered_kernel<CGAL::Simple_cartesian<double>>
        ]
        d:\cgal-3.6.1\include\cgal\create_offset_polygons_2.h(334) : 
see reference to function template instantiation 'std::vector<_Ty> 
CGAL::create_exterior_skeleton_and_offset_polygons_2<FT,Polygon,OfK,CGAL::Filtered_kernel<CK>>(const 
FT &,const Polygon &,const OfK &,const SsK &)' being compiled
        with
        [
            _Ty=PolygonPtr,
            FT=double,
            Polygon=CGAL::Polygon_2<K>,
            OfK=CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>,
            CK=CGAL::Simple_cartesian<double>,
            SsK=CGAL::Filtered_kernel<CGAL::Simple_cartesian<double>>
        ]
        d:\cgal-3.6.1\include\cgal\create_offset_polygons_2.h(343) : 
see reference to function template instantiation 'std::vector<_Ty> 
CGAL::create_exterior_skeleton_and_offset_polygons_2<FT,Polygon,CGAL::Lazy_kernel<Exact_kernel>>(const 
FT &,const Polygon &,const OfK &)' being compiled
        with
        [
            _Ty=PolygonPtr,
            FT=double,
            Polygon=CGAL::Polygon_2<K>,
            Exact_kernel=CGAL::Simple_cartesian<CGAL::Gmpq>,
            OfK=CGAL::Lazy_kernel<CGAL::Simple_cartesian<CGAL::Gmpq>>
        ]
        d:\l2b_dll\library.cpp(231) : see reference to function 
template instantiation 'std::vector<_Ty> 
CGAL::create_exterior_skeleton_and_offset_polygons_2<double,CGAL::Polygon_2<Traits_P>>(const 
FT &,const Polygon &)' being compiled
        with
        [
            _Ty=PolygonPtr,
            Traits_P=K,
            FT=double,
            Polygon=CGAL::Polygon_2<K>
        ]

When I call create_exterior_skeleton_and_offset_polygons_2.

This function uses Exact_predicates_inexact_constructions by default, 
and I don't know how to change this behaviour.

Francesc

El 12/08/2010 12:08, 

 escribió:
> You should use exact predicates and exact constructions. After all you 
> construct new points. I've tried it and wasn't able to reproduce (with 
> an exact construction kernel). I get 2 intersections.
>
> Quoting "Francesc Vila" 
> <>:
>
> > Hi,
> >
> > I am doing an intersections check using 
> > CGAL::compute_intersection_points. I am using an exact predicates and 
> > inexact constructions kernel.
> >
> > When I compute the intersections I receive an exception when is 
> > checking the precondition "comp_f(object, nodeP->object)" in 
> > CGAL::multiset. Could anyone explain why this exception is thrown?
> >
> > In the comments it says that they are checking that the tree order is 
> > not violated, but I don't see why do those segments violate the order.
> >
> > The contents of all the intersection segments is: (each line is a 
> > segment)
> >
> > ( 38029.437251200005, -91970.562748799988)   ( 38029.437251200005,  
> > 38029.437251200005)
> > ( 38029.437251200005,  38029.437251200005)   (-128029.43725120000,  
> > 38029.437251200005)
> > (-128029.43725120000,  38029.437251200005)   (-128029.43725119998,  
> > 21970.675886262117)
> > (-128029.43725119998,  21970.675886262117)   ( 21970.562748800003,  
> > 21971.675886262114)
> > ( 21970.562748800003,  21971.675886262114)   ( 21970.562748799999, 
> > -108028.50010501972)
> > ( 21970.562748799999, -108028.50010501972)   ( 258029.43725120003, 
> > -108029.37439714751)
> > ( 258029.43725120003, -108029.37439714751)   ( 258029.43725120003, 
> > -91970.562748799988)
> > ( 258029.43725120003, -91970.562748799988)   ( 38029.437251200005, 
> > -91970.562748799988)
> > (-145000.00000000000,  5000.0000000000000)   ( 275000.00000000000,  
> > 5000.0000000000000)
> >
> > Thanks in advance,
> >
> > Francesc Vila
> >
> >
> >
> > --
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