CGAL users discussion list

[Qianqian Fang <>]

hi Fernando

your attached code works nicely, and now all border nodes are
preserved.

thank you so much for your help.

Qianqian

Fernando Cacciola wrote:
> I'm afraid I would have to investigate this further but I can't do 
> that now.
> The only idea I can give you at this point is to wrap the GetCost 
> function to prevent collpasing any edge adjacent to a border edge:
>
> template<class GetCost_>
> struct Cost_with_fixed_edges : GetCost_
> {
>  typedef GetCost_ GetCost ;
>
>  typedef typename GetCost::Profile     Profile ;
>  typedef typename GetCost::Point       Point ;
>  typedef typename GetCost::result_type result_type ;
>
>  result_type operator()( Profile const& aProfile, 
> boost::optional<Point> const& aPlacement ) const
>  {
>     if ( aProfile.border_edges().size() > 0 )
>           return boost::none ;
>     else
>          return this->GetCost::operator()(aProfile, aPlacement);
>  }
> } ;
>
> typedef Cost_with_fixed_edges< SMS::Edge_length_cost<Surface> > My_cost ;
>
> int r = SMS::edge_collapse
>            (surface
>            ,stop
>            
> ,CGAL::vertex_index_map(boost::get(CGAL::vertex_external_index,surface))
>                  .edge_index_map  
> (boost::get(CGAL::edge_external_index ,surface))
>                  .get_cost        (My_cost())
>                  .get_placement   (SMS::Midpoint_placement<Surface>())
>            );
>
> HTH
>
> Fernando Cacciola
> GeometryFactory