In the example provided in Chapter 2, Finite State Machines and You, we set up our agent to detect the player tank using line of sight, which is literally a line in the form of a raycast. A raycast is a feature in Unity that allows you to determine which objects are intersected by a line cast from a point toward a given direction. While this is a fairly efficient way to handle visual detection in a simple way, it doesn't accurately model the way vision works for most entities. An alternative to using line of sight is using a cone-shaped field of vision. As the following figure illustrates, the field of vision is literally modeled using a cone shape. This can be in 2D or 3D, as appropriate for your type of game:
The preceding ...
