Game Development Reference
In-Depth Information
Let's consider the Patrol state. In the Patrol state, the Enemy should
appear
to be moving around
and to be “up to something.” In practice, this means the
Enemy
class should internally
generate a
random location inside the level
, and then move there. And when the destination is reached, the
Enemy should generate a new location elsewhere, and then move there, and so on for as long
as the Patrol state is active. Now, to achieve this, we'll need to make use of
pathfinding
and
navigation
. Before considering this, let's add a
NavMeshAgent
component to the Enemy character.
Doing this
signifies
that our Enemy will be the kind of thing that can move intelligently around the
level. To add a NavMeshAgent component, select the
Enemy_Drone
in the scene, and choose
Component
➤
Navigation
➤
Nav Mesh Agent
from the application menu (see Figure
7-12
).
The Component settings can be left at their defaults
for now
.
Figure 7-12.
Adding a NavMeshAgent component to the enemy Drone
The NavMeshAgent component will be necessary because, for the Enemy to move around the level,
pathfinding and navigation will be used. Why is this? Consider Figure
7-13
. Suppose the Enemy
(standing in position A), in a Patrol state, decides to move to a new destination (position B). The
blue arrows in Figure
7-13
indicate the route he should take to travel from A to B. We, as humans,
can clearly see and plan the route as shown, because we know certain things about the world: we
know we can't walk through walls, for example. To accommodate this, we therefore create a route
that conforms to the environment, ensuring we only travel along possible routes. But the problem is
that the enemy Drone doesn't know any of this! He would quite happily take the direct route, passing
ethereally through all walls and obstacles to reach the destination. And Unity will do absolutely
nothing to stop him. Thus, we need the Enemy to act smart and consider
obstacle avoidance
when
traveling. To solve this, we'll use the Unity NavMesh system.
