Getting an enemy to move towards you ?

Can anyone offer a relatively simple script to make an enemy move towards a FPS player.


thanks

 

found this on the forum, I tested with 2 cubes on a plane and it works but I couldn't figure out how to slow down the movement of the cube to the enemy cube ... it's instantaneous when in range (obviously from the code)
I added the 'else' statement that displays the distance for debugging purposes

Code (csharp):

1.  
2. var enemy : Transform;
3.  
4. function Update()
5.  
6. {
7.     if ( Vector3.Distance( enemy.position, transform.position ) < 500 )
8.    
9.    
10.     {
11.         print("player is close");
12.       transform.position = enemy.transform.position;
13.       transform.rotation = enemy.transform.rotation ;
14.        
15.     }
16.     else
17.        {
18.     print("not close yet");
19.     print(Vector3.Distance( enemy.position, transform.position ));
20.        }
21. }
22.  
23.  

 

Got this working but it happens in 1 second, how do I slow it down ???

Code (csharp):

1.  
2. var enemy : Transform;
3. var start: Transform;
4. var end: Transform;
5.  
6. function Update()
7.  
8. {
9.    
10.  
11. if (  Vector3.Distance( enemy.position, (Vector3.Lerp(start.position, end.position,Time.time) )) < 100  )
12.    
13.    
14.     {
15.        print("player is close");
16.        transform.position = enemy.transform.position;
17.        transform.rotation = enemy.transform.rotation ;
18.        
19.       transform.position = Vector3.Lerp(start.position, end.position, Time.deltaTime  );
20.        
21.     }
22.     else
23.     {
24.     print("not close yet");
25.     print(Vector3.Distance( enemy.position, transform.position ));
26.     }
27. }
28.  

[/code]

 

Code (csharp):

1.  
2. var enemy : Transform;
3. var speed: float;
4.  
5. function Update()
6. {
7. if (  Vector3.Distance( enemy.position, transform.position) < 100  )
8.     {
9.        print("player is close");
10.      
11.       transform.position = (enemy.position - transform.position ).normalized * speed * Time.deltaTime;
12.     }
13.     else
14.     {
15.     print("not close yet");
16.     print(Vector3.Distance( enemy.position, transform.position ));
17.     }
18. }
19.  

 

Thanks Bren, I'll try it later.

EDIT:

It didn't seem to work, the player cube just disappears

 

I guess you've checked out the Lerpz tutorial?

It's a while since I did it but there are handy enemy scripts there that may provide some useful info.

 

Speed will be in m/s, so it should be a relatively small number, depending on your scale. Start with 1 and see how that goes.

Try this one, by putting it on an enemy object.

Make sure the player is tagged Player.

It ain't pretty, but it's tested and works for me.

Code (csharp):

1. var player : GameObject;
2. var speed : float = 1;
3.  
4. function Start ()
5. {
6.      player = GameObject.FindGameObjectWithTag("Player");
7.  
8.      if (!player)
9.           Debug.Log ("ERROR could not find Player!");
10. }
11.  
12. function Update()
13. {
14.      if (!player)
15.           return;
16.  
17.      var distance = Vector3.Distance( player.transform.position, transform.position);
18.  
19.      if ( distance < 100  )
20.      {
21.           Debug.Log ("player is close");
22.          
23.           var delta = player.transform.position - transform.position;
24.           delta.Normalize();
25.          
26.           var moveSpeed = speed * Time.deltaTime;
27.      
28.           transform.position = transform.position + (delta * moveSpeed);
29.     }
30.     else
31.     {
32.           Debug.Log("not close yet " + distance);
33.     }
34. }

 

okey just give the emeny this script and take the first person player to target

Code (csharp):

1. var speed = 3.0;
2. var rotationSpeed = 5.0;
3. var shootRange = 15.0;
4. var attackRange = 30.0;
5. var shootAngle = 4.0;
6. var dontComeCloserRange = 5.0;
7. var delayShootTime = 0.35;
8. var pickNextWaypointDistance = 2.0;
9. var target : Transform;
10.  
11. private var lastShot = -10.0;
12.  
13. // Make sure there is always a character controller
14. @script RequireComponent (CharacterController)
15.  
16. function Start () {
17.     // Auto setup player as target through tags
18.     if (target == null  GameObject.FindWithTag("Player"))
19.         target = GameObject.FindWithTag("Player").transform;
20.  
21.     Patrol();
22. }
23.  
24. function Patrol () {
25.     var curWayPoint = AutoWayPoint.FindClosest(transform.position);
26.     while (true) {
27.         var waypointPosition = curWayPoint.transform.position;
28.         // Are we close to a waypoint? -> pick the next one!
29.         if (Vector3.Distance(waypointPosition, transform.position) < pickNextWaypointDistance)
30.             curWayPoint = PickNextWaypoint (curWayPoint);
31.  
32.         // Attack the player and wait until
33.         // - player is killed
34.         // - player is out of sight    
35.         if (CanSeeTarget ())
36.             yield StartCoroutine("AttackPlayer");
37.        
38.         // Move towards our target
39.         MoveTowards(waypointPosition);
40.        
41.         yield;
42.     }
43. }
44.  
45.  
46. function CanSeeTarget () : boolean {
47.     if (Vector3.Distance(transform.position, target.position) > attackRange)
48.         return false;
49.        
50.     var hit : RaycastHit;
51.     if (Physics.Linecast (transform.position, target.position, hit))
52.         return hit.transform == target;
53.  
54.     return false;
55. }
56.  
57. function Shoot () {
58.     // Start shoot animation
59.     animation.CrossFade("shoot", 0.3);
60.  
61.     // Wait until half the animation has played
62.     yield WaitForSeconds(delayShootTime);
63.    
64.     // Fire gun
65.     BroadcastMessage("Fire");
66.    
67.     // Wait for the rest of the animation to finish
68.     yield WaitForSeconds(animation["shoot"].length - delayShootTime);
69. }
70.  
71. function AttackPlayer () {
72.     var lastVisiblePlayerPosition = target.position;
73.     while (true) {
74.         if (CanSeeTarget ()) {
75.             // Target is dead - stop hunting
76.             if (target == null)
77.                 return;
78.  
79.             // Target is too far away - give up
80.             var distance = Vector3.Distance(transform.position, target.position);
81.             if (distance > shootRange * 3)
82.                 return;
83.            
84.             lastVisiblePlayerPosition = target.position;
85.             if (distance > dontComeCloserRange)
86.                 MoveTowards (lastVisiblePlayerPosition);
87.             else
88.                 RotateTowards(lastVisiblePlayerPosition);
89.  
90.             var forward = transform.TransformDirection(Vector3.forward);
91.             var targetDirection = lastVisiblePlayerPosition - transform.position;
92.             targetDirection.y = 0;
93.  
94.             var angle = Vector3.Angle(targetDirection, forward);
95.  
96.             // Start shooting if close and play is in sight
97.             if (distance < shootRange  angle < shootAngle)
98.                 yield StartCoroutine("Shoot");
99.         } else {
100.             yield StartCoroutine("SearchPlayer", lastVisiblePlayerPosition);
101.             // Player not visible anymore - stop attacking
102.             if (!CanSeeTarget ())
103.                 return;
104.         }
105.  
106.         yield;
107.     }
108. }
109.  
110. function SearchPlayer (position : Vector3) {
111.     // Run towards the player but after 3 seconds timeout and go back to Patroling
112.     var timeout = 3.0;
113.     while (timeout > 0.0) {
114.         MoveTowards(position);
115.  
116.         // We found the player
117.         if (CanSeeTarget ())
118.             return;
119.  
120.         timeout -= Time.deltaTime;
121.         yield;
122.     }
123. }
124.  
125. function RotateTowards (position : Vector3) {
126.     SendMessage("SetSpeed", 0.0);
127.    
128.     var direction = position - transform.position;
129.     direction.y = 0;
130.     if (direction.magnitude < 0.1)
131.         return;
132.    
133.     // Rotate towards the target
134.     transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
135.     transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);
136. }
137.  
138. function MoveTowards (position : Vector3) {
139.     var direction = position - transform.position;
140.     direction.y = 0;
141.     if (direction.magnitude < 0.5) {
142.         SendMessage("SetSpeed", 0.0);
143.         return;
144.     }
145.    
146.     // Rotate towards the target
147.     transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(direction), rotationSpeed * Time.deltaTime);
148.     transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);
149.  
150.     // Modify speed so we slow down when we are not facing the target
151.     var forward = transform.TransformDirection(Vector3.forward);
152.     var speedModifier = Vector3.Dot(forward, direction.normalized);
153.     speedModifier = Mathf.Clamp01(speedModifier);
154.  
155.     // Move the character
156.     direction = forward * speed * speedModifier;
157.     GetComponent (CharacterController).SimpleMove(direction);
158.    
159.     SendMessage("SetSpeed", speed * speedModifier, SendMessageOptions.DontRequireReceiver);
160. }
161.  
162. function PickNextWaypoint (currentWaypoint : AutoWayPoint) {
163.     // We want to find the waypoint where the character has to turn the least
164.  
165.     // The direction in which we are walking
166.     var forward = transform.TransformDirection(Vector3.forward);
167.  
168.     // The closer two vectors, the larger the dot product will be.
169.     var best = currentWaypoint;
170.     var bestDot = -10.0;
171.     for (var cur : AutoWayPoint in currentWaypoint.connected) {
172.         var direction = Vector3.Normalize(cur.transform.position - transform.position);
173.         var dot = Vector3.Dot(direction, forward);
174.         if (dot > bestDot  cur != currentWaypoint) {
175.             bestDot = dot;
176.             best = cur;
177.         }
178.     }
179.    
180.     return best;
181. }

i snap it from FPS tutorial

 

Thanks Bren, got it going !

It turns out that I had a massive scale, I actually had to use 50 with your code.

How do you set your scale ??? What reference do you use when starting a new scene ?


Mr Shaw, you're script uses waypoints. I havn't looked at them yet but thanks anyway.

 

I tried to add the below script to my enemy object and get this error

Assets/Standard Assets/Scripts/enemy.js(171,19): BCE0018: The name 'AutoWayPoint' does not denote a valid type.

not sure what that is..
the enemy toon has character controller on it as well as its animations.
is this a .js or .cs file as well..

thanks

 

to trinitysj:

in the fps tutorial, the enemy robot things have waypoints that they automatically move to whenever the player is not around. in order to use their a.i. you also have to import the "auto way point" script. just attach it to an empty game object to create a way point, and the robot will work.

 

thank you bren! this works and really helps with my game! one thing to keep in mind, my cube doesent rotateto face the player! help?

 

your script works great bren, Wat i need is I have to rotate the enemy to look at my Player.

 

var Player : Transform;

function Update()
{
transform.LookAt(Player);

}

 

nice！

 

hi Bren , this code is related to distance how can we change it to visibilty.
i want enemies start following when they see "player" and stop moving when sight is gone till hitting a wall.
also i expect enemies to move only X or only Z axis.

 

You need a function like this:

Code (csharp):

1.  
2. function IsVisible(object : Transform){
3.     var hits : RaycastHit[];
4.     var ray : Ray = new Ray (transform.position, transform.position-object.position);
5.    
6.     hits = Physics.RaycastAll (ray, Vector3.Distance(transform.position, object.position));
7.    
8.     for (var i = 0;i < hits.Length; i++) {
9.         var hit : RaycastHit = hits[i];
10.         var obj : Transform = hit.collider.transform;
11.         // is the object anything but this or the one we are searching for
12.         if (obj != transform   obj != object) return false;
13.         // is the object the one we are searching for?
14.         if (obj == object) return true;
15.     }
16.     // this should never happen...
17.     return true;
18. }
19.  

 

(Bren, it's 2013 now... you posted this in 2009)

Thank you.
Your script is exactly what I've been looking for...

(1) find the delta between Object and Player
(2) normalize that delta
(3) add normalized delta to Objects' new transform.

You are a godsend - thank you again.

Sincerely,
kropcke

(hope you get this)

 

Scratch that, it's now 2014! Also, my first post. Better late than never.

I came across this thread whilst looking into a simple way of implementing it and this is the gold. In fact, this is pretty much how I'd thought it would be implemented which is encouraging, because this is my first full project using Unity. Anyway, enough of the babbling; I use C# so I have converted it to C# (Not much to change at all) and added the LookAt player feature simply for convenience

Code (csharp):

1.     private GameObject player;
2.     public float speed = 1.0f;
3.  
4.     // Use this for initialization
5.     void Start () {
6.    
7.         player = GameObject.FindGameObjectWithTag ("Player");
8.  
9.         if (!player) {
10.             Debug.Log ("ERROR could not find Player!");
11.         }
12.     }
13.    
14.     // Update is called once per frame
15.     void Update () {
16.  
17.         if (!player) {
18.             return;
19.         }
20.  
21.         var distance = Vector3.Distance( player.transform.position, transform.position);
22.  
23.         if ( distance < 100  )  
24.         {  
25.             Debug.Log ("player is close");
26.             var delta = player.transform.position - transform.position;
27.             delta.Normalize();
28.             var moveSpeed = speed * Time.deltaTime;
29.             transform.position = transform.position + (delta * moveSpeed);
30.             transform.LookAt(player.transform);
31.         }
32.  
33.         else    
34.         {
35.             Debug.Log("not close yet " + distance);
36.         }