It is often the case that we need to step through our vertex arrays in a non-linear fashion. In other words, we may want to jump around the data rather than just move through it from beginning to end. For example, we might want to draw a cube where the vertex data consists of only eight positions (the corners of the cube). In order to draw the cube, we would need to draw 12 triangles (two for each face), each of which consists of three vertices. All of the needed position data is in the original eight positions, but to draw all the triangles, we'll need to jump around and use each position for at least three different triangles.
To jump around in our vertex arrays, we can make use of element arrays. The element array ...
