Unity3D 之Updatel里间隔时间调用

public GameObject projectile;
    public float fireRate = 0.5F;
    private float nextFire = 0.0F;
    void Update() {
        if (Input.GetButton("Fire1") && Time.time > nextFire) {
            nextFire = Time.time + fireRate;
            duck clone = Instantiate(projectile, transform.position, transform.rotation);
        }
    }