.. role:: blue
   :class: blue

MbVertex Vertex
===============
.. _MbVertex_Vertex_:

.. kernel version: 

The :blue:`MbVertex` class is declared in the *topology.h* file.

The MbVertex vertex is a derived class of the :blue:`MbTopologyItem`
topological object and represents a point with a known positioning
tolerance. The vertex data structure contains a
:ref:`MbCartPoint <MbCartPoint_Point_Radius_Vector_in_Two-Dimensional_Space_>` point
**point** and a positioning tolerance *tolerance* for this point.

A vertex can represent an individual point of a point frame or a joint
of edges. Any finite number of edges can meet at a vertex. Joining edges
refer to the same vertex shared by them. Fig. 1 shows a vertex where
three edges meet.

.. figure:: /MODELER/TOPOLOGICAL_OBJECTS/pictures/O.7.4.1.png
   :width: 12cm
   :align: center

   Fig. 1

In the case of an inaccurate junction of edges, the positioning
tolerance of a vertex equals the distance from the vertex point to the
end of the most distant edge. Fig. 2 shows a tolerant vertex where four
edges meet.

.. figure:: /MODELER/TOPOLOGICAL_OBJECTS/pictures/O.7.4.2.png
   :width: 12cm
   :align: center

   Fig. 2

A vertex can be named and can have attributes. The name can be used to
identify the vertex, and attributes can carry additional information
about the vertex, such as color, display style, origin, and so on. A
vertex is used in all modeling methods.