Mathf.Atan2

Description

返回其 Tan 为 y/x 的角度（以弧度为单位）。

返回值是 X 轴与 2D 向量（从零开始，在 (x,y) 处终止）之间的 角度。

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.

// Usually you use transform.LookAt for this.
// But this can give you more control over the angle

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public Transform target;

    void Update()
    {
        Vector3 relative = transform.InverseTransformPoint(target.position);
        float angle = Mathf.Atan2(relative.x, relative.z) * Mathf.Rad2Deg;
        transform.Rotate(0, angle, 0);
    }
}