【unity小技巧】实现FPS武器的瞄准放大效果（UGUI实现反向遮罩，全屏遮挡，局部镂空效果）

public class TelescopicView : MonoBehaviour
{
    public float zoomLevel = 2.0f; // 缩放倍数
    public float zoomSpeed = 10f; // 缩放速度

    private float initialFieldOfView; // 初始视野范围
    private bool isAim;//是否瞄准
    public GameObject uiWindow; // UI窗口对象

    void Start()
    {
        // 获取摄像机的初始视野范围，默认值为60
        initialFieldOfView = Camera.main.fieldOfView;
    }

    void Update()
    {
        if (Input.GetMouseButton(1))
        {
            isAim = true;
            uiWindow.SetActive(true); // 激活UI窗口
        }
        if (Input.GetMouseButtonUp(1))
        {
            isAim = false;
            uiWindow.SetActive(false); // 失活UI窗口
        }

        if (isAim)
        {
            ZoomIn();
        }
        else
        {
            ZoomOut();
        }
    }

    //视野平滑放大
    void ZoomIn()
    {
        float targetFieldOfView = initialFieldOfView / zoomLevel; // 计算目标视野范围
        Camera.main.fieldOfView = Mathf.Lerp(Camera.main.fieldOfView, targetFieldOfView, Time.deltaTime * zoomSpeed); // 平滑过渡到目标视野范围
        // 当接近目标视野范围时，直接设定为目标视野范围
        if (Mathf.Approximately(Camera.main.fieldOfView, targetFieldOfView))
        {
            Camera.main.fieldOfView = targetFieldOfView;
        }
    }

    //视野平滑缩小
    void ZoomOut()
    {
        Camera.main.fieldOfView = Mathf.Lerp(Camera.main.fieldOfView, initialFieldOfView, Time.deltaTime * zoomSpeed); // 平滑过渡回初始视野范围

        // 当接近初始视野范围时，直接设定为初始视野范围
        if (Mathf.Approximately(Camera.main.fieldOfView, initialFieldOfView))
        {
            Camera.main.fieldOfView = initialFieldOfView;
        }
    }
}