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[tang <>]

Dear 

Thank you very much for your kindly reply. I have updated the code as
follows, the function is used to remove flat triangles. Now the idea is:
1) find flat triangle and split it to 2 triangles by insertting a short
edge;
2) remove the flat triangle by joining two vertices of the short edge.

However, the code crashes at this line:
                /// split the facet
                obj->split_facet(hnew, splitedge);

Could you please help me to take a look at it? You can take the OFF file I
posted before as your test.

Thanks,
Zhanghong Tang



PS: the updated code
void RemoveFlatTriangle(myobj *object,double edgelengthmin)
{
        /// this function is used to remove flat triangles with height 
smaller than
the given threshold
        /// 1. a point will be inserted into one edge and the triangle will be
splitted into two 
        /// 2. combine the vertices of the short edge (join_vertex)
        /// Zhanghong Tang @ 10/02/2012
        Polyhedron *obj=(Polyhedron *)object->obj;
        /// check for small area triangle
        Point_3 p1, p2, p3, p;
        Line_3 l;
        Halfedge_handle h, hnew, h1, h2, h3, ho, splitedge;

        double area, d12, d23, d31, dmax;
        Facet_iterator i = obj->facets_begin();
  for (  ; i != obj->facets_end(); ++i) 
        {
                /// get 3 points of this facet(triangle)
                h1 = i->halfedge();
                h2 = h1->next();
                h3 = h2->next();
                /// (p3->p1): h1
                /// (p1->p2): h->next()
                /// (p2->p3): h->next()->next()
    p1 = h1->vertex()->point();
    p2 = h2->vertex()->point();
    p3 = h3->vertex()->point();
                Triangle_3 t(p1,p2,p3);
                area=2.0*sqrt(CGAL::to_double(t.squared_area ())); 
                d12=sqrt(CGAL::to_double(CGAL::squared_distance(p1,p2)));
                if(d12<=edgelengthmin)continue;
                d23=sqrt(CGAL::to_double(CGAL::squared_distance(p2,p3)));
                if(d23<=edgelengthmin)continue;
                d31=sqrt(CGAL::to_double(CGAL::squared_distance(p3,p1)));
                if(d31<=edgelengthmin)continue;
                dmax=max(max(d12, d23), d31);
                if(area/dmax>edgelengthmin)continue;
                /// get the projection of pi to longest edge
                if(dmax==d12)
                {
                        l=Line_3(p1,p2);
                        p=l.projection(p3);
                        splitedge = h2;  /// h2 will be splitted by p
                        h = h3;
                }
                else if(dmax==d23)
                {
                        l=Line_3(p2,p3);
                        p=l.projection(p1);
                        splitedge = h3;  /// h3 will be splitted by p
                        h = h1;
                }
                else
                {
                        l=Line_3(p3,p1);
                        p=l.projection(p2);
                        splitedge = h1;  /// h1 will be splitted by p
                        h = h2;
                }
                /// the opposite facet
                ho = splitedge->opposite()->next();
                /// split the edge
                hnew = obj->split_edge(splitedge);
                /// split the facet
                obj->split_facet(hnew, splitedge);
                /// set the new vertex
                hnew->vertex()->point() = p;
                /// split opposite facet
                hnew = obj->split_facet(ho, splitedge->opposite());
                /// combine vertices of edge h
                obj->join_vertex(hnew);
                /// after split the edge and facet, we reset the iterator to 
the beginning
of facet list
                i = obj->facets_begin();
        }
}




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