CGAL users discussion list

[Asher Kamiraze <>]

Hi all,

I am currently facing a problem with AABB Tree. I have defined my own triangle class (because I need to store an integer for each triangle) :

typedef CGAL::Simple_cartesian<double> Simple_Cartesian;
typedef Simple_Cartesian::Triangle_3   Simple_Triangle_3;

class CustomTriangle_3 : public Simple_Triangle_3
{
public:
    Simple_Cartesian::Vector_3 _normal;
    Arr::Face_handle _handle; // is an int

    CustomTriangle_3(Simple_Point_3& a, Simple_Point_3& b, Simple_Point_3& c) : Simple_Triangle_3(a,b,c) { _handle = -1; _normal = CGAL::unit_normal(a,b,c); }
    CustomTriangle_3() : Simple_Triangle_3() { _handle = -1; }
};

I then build a std::list of CustomTriangle_3 and insert them in an AABB tree:

typedef std::list<CustomTriangle_3>::iterator                  Iterator;
typedef CGAL::AABB_triangle_primitive<Simple_Cartesian,Iterator> TrianglePrimitive;
typedef CGAL::AABB_traits<Simple_Cartesian, TrianglePrimitive>   AABB_triangle_traits;
typedef CGAL::AABB_tree<AABB_triangle_traits>                    Tree;
typedef Tree::Object_and_primitive_id                            Object_and_primitive_id;
typedef Tree::Point_and_primitive_id                             Point_and_primitive_id;
typedef Tree::Primitive_id                                       Primitive_id;

std::list<CustomTriangle_3> triangles;

// some code to build CustomTriangle_3

_tree.insert(triangles.begin(),triangles.end());
_tree.build();
_tree.accelerate_distance_queries();

_tree is a class member of type Tree.

For each created triangle, I set its _handle member to a valid value (a positive integer).

Later, in an other method, I query the _tree:

if ( _tree.do_intersect(query) )
{
                std::vector<Primitive_id> intersectedPrimitives;
                _tree.all_intersected_primitives(query, std::back_inserter(intersectedPrimitives));

                //for(std::vector<Primitive_id>::iterator it=intersectedPrimitives.begin();it!=intersectedPrimitives.end();++it)
                for(unsigned int gh=0;gh<intersectedPrimitives.size();++gh)
                    _facetsToPoints[intersectedPrimitives[gh]->_handle].push_back( _points[i][j] );
                    //_facetsToPoints[(*it)->_handle].push_back( _points[i][j] );
}

This is where the problem occurs: when I try to access intersectedPrimitives[gh]->_handle, I get an inconsistent handle. If I run the program in debug mode, I got an assertion:

_expression_: list iterator not dereferencable

At the first all_intersected_primitves query, intersectedPrimitives contains 3 elements, all inconsistent (bad _handle and normal). I am wondering what I am doing wrong, and hope you could help tracking the problem.

Best regards,

Asher