AI Behavior Tree (3)

Seek

1public class Seek : Node
2{
3    private EnemyRobotBT ebt;
4
5    private float seekWaitDuration = 3;
6    private float seekWaitTimer;
7    private Vector3 seekPosition;
8
9    public Seek(BehaviorTree bt) : base(bt)
10    {
11        ebt = (EnemyRobotBT)bt;
12        seekWaitTimer = seekWaitDuration;
13    }
14
15    public override NodeState Evaluate()
16    {
17        if (!ebt.ai.seekPointReached) seekPosition = ebt.ai.lastEnemyPosition;
18
19        float remainDistance = Vector3.Distance(ebt.ai.navAgent.transform.position, seekPosition);
20        if (remainDistance <= ebt.ai.navAgent.stoppingDistance * 2)
21        {
22            seekWaitTimer -= Time.deltaTime;
23            if (seekWaitTimer < 0)
24            {
25                seekWaitTimer += seekWaitDuration;
26
27                seekPosition = CreateRandomPoint();
28                ebt.ai.seekPointReached = true;
29            }
30        }
31
32        bool success = ebt.ai.StartMove(seekPosition);
33        DebugExtension.DebugWireSphere(seekPosition, Color.green, 0.5f);
34
35        return success ? NodeState.RUNNING : NodeState.FAILURE;
36    }
37
38    private Vector3 CreateRandomPoint()
39    {
40        Vector3 randomPoint = Random.insideUnitSphere * 10 + ebt.ai.lastEnemyPosition;
41
42        NavMesh.SamplePosition(randomPoint, out NavMeshHit hit, 10, NavMesh.AllAreas);
43
44        return hit.position;
45    }
46}
47

• 마지막으로 detect 된 플레이어의 위치 (위 그림에서 Cyan Sphere) 를 기준으로
• 주변의 Random Point (위 그림에서 Green Sphere) 를 탐색한다.
• seekLevel 이 일정 수치 아래로 내려가면 Seek 를 포기하고 Patrol 를 진행한다.

Patrol

1public class Patrol : Node
2{
3    private EnemyRobotBT ebt;
4
5    private float patrolWaitDuration = 3;
6    private float patrolWaitTimer;
7
8    private int current = 0;
9    private int reverse = -1;
10
11    public Patrol(BehaviorTree bt) : base(bt)
12    {
13        ebt = (EnemyRobotBT)bt;
14        patrolWaitTimer = patrolWaitDuration;
15    }
16
17    public override NodeState Evaluate()
18    {
19        int count = ebt.ai.patrolPoints.transform.childCount;
20        Vector3 targetPosition = ebt.ai.patrolPoints.transform.GetChild(current).transform.position;
21
22        float remainDistance = Vector3.Distance(ebt.ai.navAgent.transform.position, targetPosition);
23        if (remainDistance <= ebt.ai.navAgent.stoppingDistance)
24        {
25            patrolWaitTimer -= Time.deltaTime;
26            if (patrolWaitTimer < 0)
27            {
28                patrolWaitTimer += patrolWaitDuration;
29
30                if (current == 0 || current == count - 1) reverse *= -1;
31                current += reverse;
32            }
33        }
34
35        bool success = ebt.ai.StartMove(targetPosition);
36        return success ? NodeState.RUNNING : NodeState.FAILURE;
37    }
38}
39

• 순서는 P1 → P2 → P3 → P2 → P1 이다.
• Behavior Tree 에서 가장 오른쪽에 있는 노드로, 아무 이벤트가 없을 경우 발생된다.

IsSeekLevelHigh, Walk

1public class IsSeekLevelHigh : Node
2{
3    private EnemyRobotBT ebt;
4    private float threshold = 60;
5
6    public IsSeekLevelHigh(BehaviorTree bt) : base(bt)
7    {
8        ebt = (EnemyRobotBT)bt;
9    }
10
11    public override NodeState Evaluate()
12    {
13        return ebt.ai.seekLevel.currentLevel > threshold ? NodeState.SUCCESS : NodeState.FAILURE;
14    }
15}
16

1public class Walk : Node
2{
3    private EnemyRobotBT ebt;
4
5    public Walk(BehaviorTree bt) : base(bt)
6    {
7        ebt = (EnemyRobotBT)bt;
8    }
9
10    public override NodeState Evaluate()
11    {
12        ebt.ai.inputHandler.isWalk = true;
13        ebt.ai.navAgent.speed = ebt.ai.inputHandler.maxSpeed / 3;
14
15        return NodeState.SUCCESS;
16    }
17}
18