Mathf.Atan2

Parameters

Returns

Single Angle in radians between the (x,y) vector and the (1,0) unit vector, in the range [-Pi, Pi].

Description

Returns the angle in radians whose Tan is y/x.

Return value is the angle between the x-axis unit vector (1, 0) and a 2D vector starting at zero and terminating at (x,y).

Note: This function takes account of the cases where x is zero and returns the correct angle rather than throwing a division by zero exception.

Additional resources: Tan, Atan.

using UnityEngine;

public class ExampleClass : MonoBehaviour
{
    public Transform target;
    public float turnSpeed = 2f; // higher = faster slerp

    void Update()
    {
        if (!target) return;

        // Compute desired yaw angle to target in local space
        Vector3 relative = transform.InverseTransformPoint(target.position);
        float angle = Mathf.Atan2(relative.x, relative.z) * Mathf.Rad2Deg;

        // Build target rotation around global up (yaw only)
        Quaternion targetRotation = Quaternion.Euler(0f, transform.eulerAngles.y + angle, 0f);

        // Smoothly rotate toward the target rotation
        transform.rotation = Quaternion.Slerp(
            transform.rotation,
            targetRotation,
            Time.deltaTime * turnSpeed
        );
    }
}