AI Firing

Unity Engine
1

I have one script that I use for firing, and another one that I use to get the AI to work, both listed below and in Javascript. I attach the AI script to any AI units that I want, and I attach the firing script to empties that spawn clones of one shot in a forward direction. How do I get it so that the AI fires automatically when the player is in range and in front of the AI?

AI script:

    var target : Transform; //the enemy's target
    var moveSpeed = 3; //move speed
    var rotationSpeed = 3; //speed of turning
    var attackThreshold = 3; // distance within which to attack
    var chaseThreshold = 10; // distance within which to start chasing
    var giveUpThreshold = 20; // distance beyond which AI gives up
    var attackRepeatTime = 1; // delay between attacks when within range
     
    private var chasing = false;
    private var attackTime = Time.time;
     
    var myTransform : Transform; //current transform data of this enemy
     
    function Awake()
    {
    myTransform = transform; //cache transform data for easy access/preformance
    }
     
    function Start()
    {
    target = GameObject.FindWithTag("Player").transform; //target the player
    }
     
    function Update () {
     
    // check distance to target every frame:
    var distance = (target.position - myTransform.position).magnitude;
     
    if (chasing) {
     
    //rotate to look at the player
    myTransform.rotation = Quaternion.Slerp(myTransform.rotation,
    Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed*Time.deltaTime);
     
    //move towards the player
    myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
     
    // give up, if too far away from target:
    if (distance > giveUpThreshold) {
    chasing = false;
    }
     
    // attack, if close enough, and if time is OK:
    if (distance < attackThreshold  Time.time > attackTime) {
    // Attack! (call whatever attack function you like here)
    attackTime = Time.time + attackRepeatTime;
    }
     
    } else {
    // not currently chasing.
     
    // start chasing if target comes close enough
    if (distance < chaseThreshold) {
    chasing = true;
    }
    }
    }

Firing script:

    var projectile : Rigidbody;
     
    public var speed = 10;
     
    public var destroyTime = 1;
     
    public var sound : AudioClip;
     
    function Start(){
    audio.clip = sound;
    }
     
    function Update () {
     
    if ( Input.GetButton ("Fire1")) {
     
    audio.Play();
     
    clone = Instantiate(projectile, transform.position, transform.rotation);
    clone.velocity = transform.TransformDirection( Vector3 (0, 0, speed));
     
    Destroy (clone.gameObject, destroyTime);
     
    }
    }
2

Why not use a trigger? Make the collider be the range you want. If player enters it, begin firing. If he exits, stop.

3

…

4

Ignore renman… he likes to provide counter-productive solutions.

You pretty much have everything you need right there in your scripts. All you need to do is move your fire functionality into a Fire function, rather than using Input to trigger it.

Firing script…

function Fire() {
    audio.Play();
    clone = Instantiate(projectile, transform.position, transform.rotation);
    clone.velocity = transform.TransformDirection( Vector3 (0, 0, speed));
    Destroy (clone.gameObject, destroyTime);
}

Then in your AI script, you just need to grab a reference to your firing script (im not sure what your script is called, so im going to pretend its FiringController)

var firingController : FiringController;

Start()
{
  FiringController = GetComponent<FiringController>();
}

finally, call the Fire function from your AI script.

// attack, if close enough, and if time is OK:
    if (distance < attackThreshold  Time.time > attackTime) {
       // Attack! (call whatever attack function you like here)

       attackTime = Time.time + attackRepeatTime;
       firingController.Fire();
    }
5

If you want to know if the player is in front of the AI, you can cast a raycast in the direction the AI is looking, or you could look at the dot product between the AIs looking direction vector and the direction vector from the AI to the player.

Or you could use both in a combined solution. Check with a dot product first and if it is within the right range then do a raycast check too see if line of sight is blocked between the AI and the player.

6

This is a better solution.

If you do have walls or obstacles, your current script doesn’t factor that, and you’ll end up having your AI trying to shoot you through a wall or trying to walk through a wall to get to you.

Probably overkill for what you are trying to achieve, but something to bear in mind.

7

Actually, that’s kinda cool.