CGAL 4.12  Triangulated Surface Mesh Simplification

The concept GetPlacement
describes the requirements for the policy function object which gets the collapse placement of an edge, that is, the new position of the vertex that remains after a halfedgecollapse operation.
The placement returned is a boost::optional
value (i.e., it can be absent). An absent result indicates that the remaining vertex must be kept in place, not moved to a new position.
Operations  
template<class Profile >  
boost::optional< Point >  operator() (Profile const &edge_profile) const 
Computes and returns the placement, that is, the position of the vertex which replaces the collapsing edge (represented by its profile). More...  
boost::optional<Point> GetPlacement::operator()  (  Profile const &  edge_profile  )  const 
Computes and returns the placement, that is, the position of the vertex which replaces the collapsing edge (represented by its profile).
Profile  must be a model of EdgeProfile . 