CGAL 5.0  Triangulated Surface Mesh Simplification

#include <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Constrained_placement.h>
BasePlacement.
The class Constrained_placement
is a model for the GetPlacement
concept provided the template parameter BasePlacement
is such a model.
The placement of the vertex resulting from a contraction of an edge adjacent to a constrained edge is the point of the common vertex. Otherwise the placement is the one computed by BasePlacement
.
BasePlacement  a model of GetPlacement . 
EdgeIsConstrainedMap  a model of boost::ReadablePropertyMap with GetPlacement::Profile::edge_descriptor as key type and bool as value type indicating if an edge is constrained. 
Creation  
Constrained_placement (EdgeIsConstrainedMap map=EdgeIsConstrainedMap(), BasePlacement base=BasePlacement())  
Constructor.  