CGAL users discussion list

[Matthijs Sypkens Smit <>]

Hi,

I'm wondering if there is a clean way to use a class-method as a callback 
when intersecting boxes. I solved the problem by using a static method, 
but this feels really dirty. With the current implementation the class may 
only be instantiated once, or else things might break.

Depending on the intersection of the boxes I want to access and modify 
additional data structures. Of course I would like this data to reside in 
a class rather than being global.
To make it more clear, here is the call I make:
CGAL::box_intersection_d( triangle_boxes.begin(), triangle_boxes.end(), 
query.begin(), query.end(), cb_aid.callback);

cb_aid is of object of type CallbackAid, that looks roughly like this:
class CallbackAid;

class CallbackAid
{
private:
    static CallbackAid *pObject;
    Point p;

public:
    std::map<Point,double>  mydata;

    CallbackAid() { pObject = this; }
    ~CallbackAid() {}

    static void CallbackAid::callback( const Box &box_a, const Box &box_b )
    {
        CallbackAid *me = (CallbackAid *)pObject;
        [...]
        me->mydata[q] = value;
    }
}

further I need to define the value of the static class variable:
CallbackAid * CallbackAid::pObject = (CallbackAid *)NULL;

Depending on the result of the intersections I can thus modify 'mydata' 
which can be accessed by yet other routines. Is there a cleaner way to do 
this, preferably using a normal class method as a callback instead of the 
static one? I looked into this a while ago and remember then coming to the 
conclusion that is was not possible, but I would be happy to be told 
otherwise.

If the problem is not clear, please say so and I'll try to clarify.


-- 
Matthijs Sypkens Smit