CGAL users discussion list

["Fernando Cacciola" <>]

Hi Qianqian,
> thank you Fernando
>
> Now the code compiles normally. Unfortunately, the simplified surface mesh
> is similar to the
> old one:some of the border edges were collapsed.
>
> [SNIP]
>
> I don't want to spend too much of your time on this, but if you have some
> quick
> thoughts or ideas where to look at, that would be great help.
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