首先獲取相機物件：

        //camera = GetComponent<Camera>();  //指令碼在相機物件上
        //GameObject.FindWithTag("MainCamera") //根據Tag查詢
         //主相機
        camera = Camera.main; 

方式一：用標誌位控制近遠兩種狀態切換，一次拉近拉遠

    private bool isFar = true;
    private void Zoom1()
    {
        if (Input.GetMouseButtonDown(1))
        {
            //修改縮放等級
            isFar = !isFar;
            if (isFar)
            {
                //拉遠 20  --》 60
                camera.fieldOfView = 60;
            }
            else
            {
                //拉近 60 --》 20
                camera.fieldOfView = 20;
            }
        }
    }
 

方式二：逐漸拉近拉遠

    private void Zoom2()
    {
        if (Input.GetMouseButtonDown(1))
        {
            //修改縮放等級
            isFar = !isFar; 
        } 
        if (isFar)
        {
            //拉遠 20  --》 60
            if (camera.fieldOfView < 60)
                camera.fieldOfView += 2;
        }
        else
        {
            //拉近 60 --》 20
            if (camera.fieldOfView > 20)
                camera.fieldOfView -= 2;
        }
    }
 

方式三：速度動態變化，開始快靠近目標時慢

    private void Zoom3()
    {
        if (Input.GetMouseButtonDown(1))
        {
            //修改縮放等級
            isFar = !isFar;
        }
        if (isFar)
        {
            //拉遠 20  --》 60        Lerp(起點、終點、比例)
            camera.fieldOfView = Mathf.Lerp(camera.fieldOfView, 60, 0.1f);
            //Vector3.Lerp
            //Quaternion.Lerp
            //Color.Lerp
        }
        else
        {
            //拉近 60 --》 20
            camera.fieldOfView = Mathf.Lerp(camera.fieldOfView, 20, 0.1f);
        }
    }
 

方式四：用陣列控制多個等級的縮放

    //60    50  40  30    20　定義縮放等級陣列
    public float[] zoomLevels;
    private int currentLevel;
    private void Zoom()
    {
        if (Input.GetMouseButtonDown(1))
        {
            //修改縮放等級
            //currentLevel++;
            //currentLevel = currentLevel < zoomLevels.Length - 1 ? currentLevel + 1 : 0;
            currentLevel = (currentLevel + 1) % zoomLevels.Length;
        }
        camera.fieldOfView = Mathf.Lerp(camera.fieldOfView, zoomLevels[currentLevel], 0.1f); 
    }