How to make top-down objects rotate to face another?

Questions & Answers
1

As the title says, I am making a top down style game, and am having difficulty getting enemies to rotate to face the player properly. I found this code from another post, and have tried tweaking the values of Vector3.RotateTowards, but I can’t quite get the result I’m looking for.

public Transform target;

	public float speed;

	void Update() {

	Vector3 targetDir = target.position transform.position;
		float step = speed * Time.deltaTime;
		float moveStep = moveSpeed * Time.deltaTime;
		Vector3 newDir = Vector3.RotateTowards(transform.forward, targetDir, step, 0.0F);
		transform.rotation = Quaternion.LookRotation(newDir);

With this code, the enemy will rotate on all 3 axes, but will eventually become ‘invisible’. How do I isolate just the ‘z’ axis?

Thanks!

edit: I know this question has been brought up before, but I’ve looked through all the solutions I’ve found and haven’t been able to find one that suits my needs.

2

You say ‘top-down’. Top-down to me is a game played on the XZ plane with the camera looking down the ‘Y’ axis. You say 'isolate just the ‘z’ axis. This implies a game where the camera is looking towards positive ‘z’…perhaps a 2D game. So if this is true, you can do an immediate rotation by:

Vector3 dir = target.position - transform.position;
float angle = Mathf.Atan2(dir.y,dir.x) * Mathf.Rad2Deg;
transform.rotation = Quaternion.AngleAxis(angle, Vector3.forward);

If you want to rotate over time as implied by the RotateTowards, you can do use Quaternion.RotateTowards():

#pragma strict

var target : Transform;
var speed = 90.0;

private var qTo : Quaternion;

function Update () {
    var lookPos = target.position - transform.position;
    var angle : float = Mathf.Atan2(lookPos.y, lookPos.x) * Mathf.Rad2Deg;
    qTo = Quaternion.AngleAxis(angle, Vector3.forward);
    transform.rotation = Quaternion.RotateTowards(transform.rotation, qTo, speed * Time.deltaTime);
}