The Renderer class is an abstract class which is introduced to allow
the graphical display of the 3d finite element model. The Renderer class
is an abstract class, it defines the interface all concrete subclasses
must provide. In common with most rendering packages, the interface
allows only for the displaying of a few basic primitive objects, lines
and polygons (commercial renderers offer others such as cubes,
circles, cones). By providing only a few basic primitives, the
interface will allow complicated scenes to be created (much like the
ten digits 0-9 allows an infinite number of numbers to be created).
Unlike commercial renderers there is no concept of the optical
properties of materials and light sources in the interface. This is
because the image the analyst is looking for is not a photo realistic
image of the model, rather an image indicating the basic model,
stresses, and nodal displacements.
Renderer(