private GameObject center;
private float rotateSpeed = 40f;

private float rotateZ = 0;
private float minR = -15f;
private float maxR = 15f;
private float sensitity = 50f;

void Start()
{
　　//获取物体
　　center = GameObject.Find("center");
}

//鼠标拖动事件写在Update()中
if (Input.GetMouseButton(0))
{
　　float rotateY = center.transform.localEulerAngles.y - Time.deltaTime * sensitity*Input.GetAxis("Mouse X");
　　if (rotateY>=0&&rotateY<=180)
　　{
　　　　rotateZ += Time.deltaTime * sensitity * Input.GetAxis("Mouse Y");
　　}
　　else
　　{
　　　　rotateZ -= Time.deltaTime * sensitity * Input.GetAxis("Mouse Y");
　　}
　　//控制上下移动的范围
　　rotateZ = Mathf.Clamp(rotateZ, minR, maxR);
　　center.transform.eulerAngles = new Vector3(0, rotateY, rotateZ);　　

}

鼠标的拖动实现物体的上下左右移动