Implementing behavior trees

Behavior trees can be seen as a synthesis of a number of other artificial intelligence techniques, such as finite-state machines, planning, and decision trees. In fact, they share some resemblance to FSMs, but instead of states, we think in terms of actions spanned across a tree structure.

Getting ready

This recipe requires us to understand coroutines.

How to do it...

Just like decisions trees, we will create three pseudo-abstract classes for handling the process:

1. First, let's create the Task base class, as shown in the following code:

using UnityEngine; 
using System.Collections; 
using System.Collections.Generic; 
 
public class Task : MonoBehaviour 
{

 

 

    public List<Task> children; 
    protected bool result = false; 
    protected bool isFinished = false; 
} 

2. Next, we're going to implement the finalization function, as shown in the following code:

public virtual void SetResult(bool r) 
{ 
    result = r; 
    isFinished = true; 
} 

3. We then implement the function...