理解

mousePos - transform.position 鼠標的位置減去掛在此腳本上物體的位置

z = -Vector3.Angle(Vector3.up, mousePos - transform.position); Vector3.up為（0,1,0），
這句話暫時理解為（0,1,0）和mousePos - transform.position夾角

  //Canvans下的物體
 2     public RectTransform UGUICanvans;
 3     //當前主相機
 4     public Camera mainCamera;
 5 
 6     void Update()
 
 
7     {
 8         Vector3 mousePos;
 9         //ScreenPointToWorldPointInRectangle(RectTransform rect, Vector2 screenPoint, Camera cam, out Vector3 worldPoint);
10         RectTransformUtility.ScreenPointToWorldPointInRectangle(UGUICanvans, new Vector2(Input.mousePosition.x, Input.mousePosition.y),mainCamera, out
 
 mousePos);
11         float z;
12         if (mousePos.x > transform.position.x)
13         {
14             //返回的鼠標的位置-transform.position槍的位置
15             z = -Vector3.Angle(Vector3.up, mousePos - transform.position);
16             
17         }
18         else
19         {
20             z = Vector3.Angle(Vector3.up, mousePos - transform.position);
 
21         }
22         transform.localRotation = Quaternion.Euler(0, 0, z);
23     }

 

二維物體跟隨鼠標移動