1 using UnityEngine; 2 using System.Collections; 3  4 public class ShouShi : MonoBehaviour 5 { 6     public Transform centerTra;//围绕旋转的中心 7     public Transform targetTra;//移动目标 8     private Vector2 oldPos;//上一帧位置 9     private float angular;10     private float speed = 0.1f;//升降速度11     void Update()12     {13         if (Input.GetMouseButtonDown(0))14         {15             oldPos = Input.mousePosition;16         }17         18         if (Input.GetMouseButton(0))19         {20             Vector3 point = Camera.main.WorldToScreenPoint(centerTra.position );//中心点转换为屏幕坐标21             angular = SignedAngularGap(new Vector2(point.x, point.y), oldPos, Input.mousePosition);22             print(angular);23             float y = targetTra.position.y;24             y += angular * speed * Time.deltaTime;25             targetTra.position = new Vector3(targetTra.position.x, y, targetTra.position.z);26             oldPos = Input.mousePosition;27         }28     }29 30     public static float SignedAngle(Vector2 from, Vector2 to)31     {32         // perpendicular dot product33         float perpDot = (from.x * to.y) - (from.y * to.x);34         return Mathf.Atan2(perpDot, Vector2.Dot(from, to));35     }36     // return signed angle in degrees between current finger position and ref positions37     static float SignedAngularGap(Vector2 center, Vector2 oldPos, Vector2 newPos)38     {39         Vector2 refDir = (oldPos - center).normalized;40         Vector2 curDir = (newPos - center).normalized;41 42         // check if we went past the minimum rotation amount treshold43         return Mathf.Rad2Deg * SignedAngle(refDir, curDir);44     }45 }