Broadly speaking, the creation of an image on a computer graphics screen can be thought of as consisting
of a geometry stage and a rendering stage. In existing systems, the geometry stage is responsible for transformation
and lighting, in which the 3D object is converted into a number of polygons defined by a set of suitable primitives.
Consider an interactive computer game where the user controls the motion of his player, as the player moves forward
or backward the objects in the frame will need to be transformed so that they appear closer to and further away from
the user, respectively