CG Basics - An Introduction to Computer Graphics for Artists - page 23

Fig. 2.16 To make a polygonal face, vertices and edges are defi ned fi rst

Fig. 2.17 The direction of a vector is written as a single coordinate. All vectors start at the world
origin

2.4.1.4 Vector

A vector is a direction. Vectors are not rendered but they are important because
they are required for lighting and animation. To defi ne a vector, a single three axis
coordinate is used. This is suffi cient, because part of the vector defi nition is that
the origin of the direction is located at 0 0 0 in world space. This allows any
single coordinate to represent any direction in world space (Fig. 2.17 ).