CGAL users discussion list

[Martin Mörth <>]

Hello Again!

I stumbled across another problem. This time when using
Incremental_neighbor_search in conjunction with an exact kernel.

] typedef CGAL::Exact_predicates_exact_constructions_kernel CgKernel;
] typedef CgKernel::Point_2 CgPoint;
] 
] typedef CGAL::Search_traits_2< CgKernel > CgSearchTraits;
] typedef CGAL::Kd_tree< CgSearchTraits,
]   CGAL::Sliding_midpoint< CgSearchTraits > > CgKdTree;
] 
] typedef CGAL::Incremental_neighbor_search< CgSearchTraits,
]   CGAL::Euclidean_distance< CgSearchTraits >,
]   CGAL::Sliding_midpoint< CgSearchTraits >, CgKdTree > CgSearch;
] typedef CgSearch::iterator CgSearchIter;
] 
] CgKdTree tree;
] tree.insert( CgPoint(  1.0, 1.5 ) );
] tree.insert( CgPoint( -1.0, 1.5 ) );
] tree.insert( CgPoint(  0.0, 0.5 ) );
] 
] CgSearch search( tree, CgPoint( 0.0, 0.0 ) ); // crash here
] CgSearchIter iter = search.begin();
] assert( ( *iter ).first == CgPoint( 0.0, 0.5 ) );

When I run a test program containing the code shown above
the application crashes in the line where 'search' is constructed.
The debugger says: 'Access violation reading location 0xfdfdfe0d'

Execution stack backtrace can be found here:
http://www.sbox.tugraz.at/home/m/mmoerth/cgal/crash_backtrace.txt

Digging deeper it seems the problem occurs in line 310 of
incremental_neighbor_search.h where a bounding box is
calculated:

] Node_box *bounding_box = new Node_box((tree.bounding_box()));

The crash seems to be related to a subtraction in line 91 of
kd_tree_rectangle.h:

] FT span = upper_[0]-lower_[0];

After switching the kernel to 'Simple_homogeneous< double >'
the program runs fine. This may [ :-) ] indicate that the code
itself is OK.

Are there any restrictions to which kernels I can use with
Kd_tree / Incremental_neighbor_search?

I am using CGAL 3.4 and VS 8.0 on Windows XP.

Thanks for any help on this!

Martin
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