 
default constructor.

All nonconst methods listed below also have const counterparts that return constant handles, iterators or circulators:

 checks whether the vertex lies at infinity and not associated with a point with bounded coordinates.  

 checks whether the vertex is isolated (i.e., has no incident edges).  

 returns the number of edges incident to v.  


returns a circulator circulator that allows going over the halfedges
incident to v (that have v as their target).
The edges are traversed in a clockwise direction around v.
 


returns a handle to the face that contains v in its interior.
 


returns the point associated with the vertex.
 

 returns the placement of the xcoordinate in the parameter space, that is, either the left boundaryside, the interior, or the right boundaryside.  

 returns the placement of the ycoordinate in the parameter space, that is, either the bottom boundaryside, the interior, or the top boundaryside. 