CGAL users discussion list

[Martin Baeker <>]

Dear experts,

I still have not solved the problem described below. I tried to insert
the segments one by one as follows:

Pmwx pm;
for (unsigned int i=0; i< seglist.size(); i++)
   pm.insert(seglist[i]);

but still one of the segments is missing from the planar map in some cases.

I would really appreciate any insight on why this can happen and what
to do about it. Is there any kind of assertion I can use to check
whether  the segment was actually inserted? 

Thanks,

Martin.

PS: I still use CGAL 3.1 - is there a chance that upgrading to a later
version will help?



> Dear all,
> 
> I just encountered a puzzling behaviour in a Planar map.
> 
> I use the following code fragment to create  the planar map:
> 
> 
> std::vector<Segment> seglist //This is the standard template library vector 
> class
> ... seglist filled with values
> Pmwx pm;
> pm.insert(seglist.begin(), seglist.end());
> std::cout << "\n\nWriting pm's halfedges" << std::endl;
> Pmwx::Halfedge_const_iterator eit;
>   for (eit = pm.halfedges_begin(); eit != pm.halfedges_end(); ++eit, ++eit) 
> {
>     std::cout << eit->source()->point()
>               << " --- " << eit->target()->point() << std::endl;
>   }
> 
> In most cases, this works fine, but
> I just encountered a case where one of the elements of a
> seglist is missing in the Pmwx  pm (and it is neither the first nor the
> last element, so it seems not to be a problem with the
> seglist.begin() or end()).
> 
> Here's the bunch of defintions I use:
>  typedef CGAL::Quotient<CGAL::MP_Float>                      NT;
>  typedef CGAL::Cartesian<NT>                                 TutorialR;
> typedef CGAL::Segment_2<TutorialR>                           Segment;
> typedef CGAL::Arr_segment_traits_2<TutorialR>                  Traits;
> typedef CGAL::Pm_default_dcel<Traits>     Dcel;
> typedef CGAL::Planar_map_2<Dcel,Traits>   Planar_map;
> typedef CGAL::Planar_map_with_intersections_2<Planar_map> Pmwx;
> 
> I don't know if looking at the actual values can help in understanding
> this problem, but just in case, I'll show them here:
> 
> This is the contents of seglist:
> 
>  i: 0 0.10000008344650269/1 0.012000012211501598/1 - 0.24999982118606567/1 
> 0.012000012211501598/1
>  i: 1 0.10000009089708328/1 5.8278321573111952e-38/1 - 
> 0.10000008344650269/1 0.012000012211501598/1
>  i: 2 0.10000009089708328/1 5.8278321573111952e-38/1 - 
> 0.26000073552131653/1 4.9593527711929177e-38/1
>  i: 3 0.26000073552131653/1 4.9593527711929177e-38/1 - 
> 0.25993925333023071/1 0.00057996663963422179/1
>  i: 4 0.25993925333023071/1 0.00057996663963422179/1 - 
> 0.25975009799003601/1 0.0011668455554172397/1
>  i: 5 0.25975009799003601/1 0.0011668455554172397/1 - 0.25943571329116821/1 
> 0.0017639140132814646/1
>  i: 6 0.25943571329116821/1 0.0017639140132814646/1 - 0.25900107622146606/1 
> 0.0023707395885139704/1
>  i: 7 0.25900107622146606/1 0.0023707395885139704/1 - 0.25845640897750854/1 
> 0.0029852592851966619/1
>  i: 8 0.25845640897750854/1 0.0029852592851966619/1 - 0.25781622529029846/1 
> 0.0036053736694157124/1
>  i: 9 0.25781622529029846/1 0.0036053736694157124/1 - 0.25709828734397888/1 
> 0.0042295018211007118/1
>  i: 10 0.25709828734397888/1 0.0042295018211007118/1 - 
> 0.25632262229919434/1 0.004856607411056757/1
>  i: 11 0.25632262229919434/1 0.004856607411056757/1 - 0.25551068782806396/1 
> 0.0054860818199813366/1
>  i: 12 0.25551068782806396/1 0.0054860818199813366/1 - 
> 0.25468483567237854/1 0.0061176484450697899/1
>  i: 13 0.25468483567237854/1 0.0061176484450697899/1 - 
> 0.25386759638786316/1 0.0067513072863221169/1
>  i: 14 0.25386759638786316/1 0.0067513072863221169/1 - 0.2530810534954071/1 
> 0.0073873363435268402/1
>  i: 15 0.2530810534954071/1 0.0073873363435268402/1 - 0.25234633684158325/1 
> 0.0080263437703251839/1
>  i: 16 0.25234633684158325/1 0.0080263437703251839/1 - 
> 0.25168305635452271/1 0.0086693689227104187/1
>  i: 17 0.25168305635452271/1 0.0086693689227104187/1 - 
> 0.25110900402069092/1 0.0093179969117045403/1
>  i: 18 0.25110900402069092/1 0.0093179969117045403/1 - 
> 0.25064021348953247/1 0.0099743315950036049/1
>  i: 19 0.25064021348953247/1 0.0099743315950036049/1 - 
> 0.25029110908508301/1 0.010640442371368408/1
>  i: 20 0.25029110908508301/1 0.010640442371368408/1 - 0.25007474422454834/1 
> 0.011316764168441296/1
>  i: 21 0.25007474422454834/1 0.011316764168441296/1 - 0.24999982118606567/1 
> 0.012000012211501598/1
> 
> And this is the output from the above code fragment when given this seglist:
> Writing pm's halfedges
> 0.10000008344650269/1 0.012000012211501598/1 --- 0.24999982118606567/1 
> 0.012000012211501598/1
> 0.25007474422454834/1 0.011316764168441296/1 --- 0.24999982118606567/1 
> 0.012000012211501598/1
> 0.25029110908508301/1 0.010640442371368408/1 --- 0.25007474422454834/1 
> 0.011316764168441296/1
> 0.25064021348953247/1 0.0099743315950036049/1 --- 0.25029110908508301/1 
> 0.010640442371368408/1
> 0.25110900402069092/1 0.0093179969117045403/1 --- 0.25064021348953247/1 
> 0.0099743315950036049/1
> 0.25168305635452271/1 0.0086693689227104187/1 --- 0.25110900402069092/1 
> 0.0093179969117045403/1
> 0.25234633684158325/1 0.0080263437703251839/1 --- 0.25168305635452271/1 
> 0.0086693689227104187/1
> 0.2530810534954071/1 0.0073873363435268402/1 --- 0.25234633684158325/1 
> 0.0080263437703251839/1
> 0.25386759638786316/1 0.0067513072863221169/1 --- 0.2530810534954071/1 
> 0.0073873363435268402/1
> 0.25468483567237854/1 0.0061176484450697899/1 --- 0.25386759638786316/1 
> 0.0067513072863221169/1
> 0.25551068782806396/1 0.0054860818199813366/1 --- 0.25468483567237854/1 
> 0.0061176484450697899/1
> 0.25632262229919434/1 0.004856607411056757/1 --- 0.25551068782806396/1 
> 0.0054860818199813366/1
> 0.25709828734397888/1 0.0042295018211007118/1 --- 0.25632262229919434/1 
> 0.004856607411056757/1
> 0.25781622529029846/1 0.0036053736694157124/1 --- 0.25709828734397888/1 
> 0.0042295018211007118/1
> 0.25845640897750854/1 0.0029852592851966619/1 --- 0.25781622529029846/1 
> 0.0036053736694157124/1
> 0.25900107622146606/1 0.0023707395885139704/1 --- 0.25845640897750854/1 
> 0.0029852592851966619/1
> 0.25943571329116821/1 0.0017639140132814646/1 --- 0.25900107622146606/1 
> 0.0023707395885139704/1
> 0.25975009799003601/1 0.0011668455554172397/1 --- 0.25943571329116821/1 
> 0.0017639140132814646/1
> 0.25993925333023071/1 0.00057996663963422179/1 --- 0.25975009799003601/1 
> 0.0011668455554172397/1
> 0.10000009089708328/1 5.8278321573111952e-38/1 --- 0.26000073552131653/1 
> 4.9593527711929177e-38/1
> 0.26000073552131653/1 4.9593527711929177e-38/1 --- 0.25993925333023071/1 
> 0.00057996663963422179/1
> 
> As you can see, the second entry (i:1) of the seglist is missing.
> 
> If anybody can give me a hint on what the error might be, I'd be very
> grateful, for I'm completely stymied.
> 
> Thanks a lot,
> 
> Martin.
> 
>                    Priv.-Doz. Dr. Martin Bäker
>                    Institut für Werkstoffe
>                    Technische Universität Braunschweig
>                    Langer Kamp 8
>                    38106 Braunschweig
>                    Germany
>                    Tel.: 00-49-531-391-3073                      
>                    Fax   00-49-531-391-3058
>                    e-mail 
> <>
>  
> 
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                   Priv.-Doz. Dr. Martin Bäker
                   Institut für Werkstoffe
                   Technische Universität Braunschweig
                   Langer Kamp 8
                   38106 Braunschweig
                   Germany
                   Tel.: 00-49-531-391-3073                      
                   Fax   00-49-531-391-3058
                   e-mail 
<>