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["peter heppel" <>]

Hello

I'm getting a lot of precondition violations with 2D polygon boolean
operations using CGAL::Exact_predicates_inexact_constructions_kernel

Here's just one test case which failed.  The enclosed PDF shows the data. If
anyone can replicate the failure I'd appreciate some advice on a
work-around.  An exact data type isnt an option because of the run-time. 

The output is
' CGAL error: precondition violation!
Expr: comp_f(object, nodeP->object) != LARGER
File: c:\program files\cgal-3.3\include\cgal\multiset.h
Line: 2141
Explanation:Make sure the insertion does not violate the tree order(2)'


This occurs while executing 
theSet.intersection(pgn);

where the declarations are

Polygon_2 pgn;
Polygon_set_2 theSet; 

And the values are
Pgn is:
     7.1268867,   0.411146536
     9.1268867,   0.411146536
     9.1268867,    17.9511202
     7.1268867,    17.9511202

theSet consists of a single pwh which doesn’t have holes. 
It is simple and concave. 
This pwh's outer boundary is

    9.14120777,    5.38700087
    9.59561777,    6.40550604
    10.6611309,    6.70322293
    11.7893212,    6.78156949
    11.6326281,    7.65905087
    10.0186891,    7.50235776
    10.2067209,    8.58354018
     9.8070098,    8.59920949
    7.90838222,    8.97393861
     5.7516079,    7.62491375
    5.77658984,    7.27516657
    6.07637315,    7.30014851
    6.35950182,    7.38342165
    6.78419483,    7.50000404
    7.02568694,    7.40840359
    7.19223322,    7.15025686
    7.11728739,    6.95872864
    6.93408648,    6.86712818
    6.69259438,     6.8754555
     6.6426305,    7.00869252
    6.80084946,    7.10862029
    6.93408648,    7.10862029
    6.90910454,    7.21687537
    6.71757632,    7.30847582
    6.50106616,    7.18356611
    6.36782913,    6.90876475
    6.32619257,    6.68392728
    6.70924901,    6.54236294
    6.95906843,    6.55069025
    7.28383367,    6.69225459
    7.56696234,    6.64229071
    7.62525354,    6.41745323
     7.6585628,    5.97610559
    7.57528966,    5.64301303
    7.38376144,    5.53475795
    7.03401425,    5.47646675
    6.32619257,    5.49312138
    6.30953794,     5.6846496
    6.32619257,    6.08436067
    6.71757632,    6.22592501
    7.13394202,    6.30919815
    7.09230545,     6.1010153
    6.84248603,    6.05937873
    6.60932124,    5.94279633
     6.6426305,    5.77625005
    6.93408648,      5.801232
    7.23386979,    5.84286857
    7.28383367,    6.14265187
    7.25885173,    6.45076249
    6.44277496,    6.32585278
    5.88484493,    6.09268799
    5.81822641,    5.15170151
    5.74328059,    4.56046222
    5.76826253,    4.05249607
     6.1679736,    3.86929516
    7.10063276,    3.78602202
    7.63358086,    4.04416875
    7.76681788,     4.4938437
      7.716854,    4.95184597
    7.23386979,    5.09341031
    6.41779302,    5.03511911
    6.40113839,    4.65206267
    6.97572305,    4.62708073
    7.10063276,    4.82693626
    7.37543412,    4.84359089
    7.38376144,    4.57711684
    7.01735962,    4.35227937
    6.65095781,    4.31897011
     6.1096824,    4.39391594
    6.13466434,    4.63540804
    6.14299166,    4.81028164
    6.10135509,    4.93519134
    6.27622868,    5.04344643
    6.19295554,    5.15170151
    6.67593975,    5.24330196
    7.40874338,    5.30992047
    7.75849057,    5.22664733
    8.11656507,    5.39319361
    8.10823775,    5.07675568
    8.23314746,    4.91853672
    8.11656507,    4.51882565
    8.21190456,    3.56246812
    7.51549076,    3.19491639
    6.70300801,    3.15622674
    6.37414594,    2.65326122
     6.6256287,    2.45981294
    7.28335283,    2.74998536
    7.55418042,    2.20833019
    7.07055973,    2.20833019
    6.78038732,    1.87946812
    6.35480111,    2.11160605
    6.25807697,    1.55060605
    6.43218042,    1.12501984
     5.9292149,   0.699433634
    6.25807697,   0.660743978
    6.84630743,   0.274603014
    9.84630743,   0.274603014
    12.8463074,    2.27460301
    13.5839186,    4.39401721
    12.8304808,    5.96938726
    11.5975825,    5.96938726
    10.2276954,    5.83239856
    9.95371805,    4.46251156
    10.0907067,     3.4350963
     11.323605,    3.91455675
    11.7345712,    4.73648896
    12.2437312,    4.50951949
    12.1653847,    3.89841638
    11.7423133,     3.3186519
    11.2879033,    2.89558052
    10.5827843,    2.77022604
    9.72097225,    2.89558052
    9.45459397,    3.30298259
    9.29790087,    4.00810156


Peter
email: 

 
(SUI)     +41  218 621 015

(mob)   +33   681307652

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            Peter Heppel Associates

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            75010 Paris – France


www.peterheppel.com


-----Original Message-----
From: Zorglub78 
[mailto:]
 
Sent: Wednesday, August 29, 2007 8:12 AM
To: 

Subject: [cgal-discuss] Bug in Nef_polyhedron_3 (II v_first, II v_last) ?

Hi all,

When I try to use this very trivial code:

#include <CGAL/basic.h>
#include <CGAL/Gmpq.h>
#include <CGAL/Homogeneous.h>
#include <CGAL/Nef_polyhedron_3.h>

typedef CGAL::Gmpz NT;
typedef CGAL::Homogeneous<NT> Kernel3D;
typedef Kernel3D::Point_3                                      Point3D;
typedef CGAL::Iso_cuboid_3<Kernel3D>                           Cuboid3D;
typedef CGAL::Nef_polyhedron_3<Kernel3D>                       Polyhedron3D;

using std::vector;

int main(int argc, char** argv)
{
 
  Cuboid3D c1(Point3D(0,0,0), Point3D(3,3,3));
  vector<Point3D> vp;
  for(u_int i=0; i<8; ++i)
    vp.push_back(c1[i]);
 
  Polyhedron3D p(vp.begin(), vp.end(), true);
}

Execution fails with the following error:
"Conversion from vertex cycle to Nef_polyhedron_3 was not successful. 
Error history: Direction of projection is 'z'. -> Different vertices are 
projected to same location! Now, direction of projection is 'x'. -> 
Different vertices are projected to same location! Now, direction of 
projection is 'y'. -> Different vertices are projected to same location! 
Finally, empty Nef_polyhedron_3 was constructed."

Am I doing wrong something, or is there a bug in Nef_polyhedron_3 (II 
v_first, II v_last) ?

Thanks for responses.


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Attachment: failedintersect.pdf
Description: Adobe PDF document