unity实现车方向盘转动效果

效果：

c#脚本如下：

using System;using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.EventSystems;public class NewBehaviourScript : MonoBehaviour, IDragHandler,IBeginDragHandler,IEndDragHandler{    /// <summary>    /// 需要旋转的模型    /// </summary>    public Transform model;    /// <summary>    /// 父物体的recttransform    /// </summary>    public RectTransform parentRect;    /// <summary>    /// 旋转的UI    /// </summary>    public RectTransform img;    /// <summary>    /// 摄像机    /// </summary>    public Camera cam;    /// <summary>    /// 是否在拖拽    /// </summary>    private bool drag = false;    /// <summary>    /// 初始角度    /// </summary>    private float originAngle = 0;    /// <summary>    /// 自身角度    /// </summary>    private float selfAngle1 = 0;    /// <summary>    /// 上一次和当前的角度    /// </summary>    private float lastAngle = 0f;    private float currentAngle = 0f;    /// <summary>    /// 上一次和当前的位置    /// </summary>    private Vector2 currentPos;    private Vector2 lastPos;    public void OnBeginDrag(PointerEventData eventData)    {        drag = true;        originAngle = GetAngle(eventData.position);        selfAngle1 = (img.transform as RectTransform).eulerAngles.z;    }    public void OnDrag(PointerEventData eventData)    {        if (drag)        {            lastAngle = currentAngle;            currentAngle = GetAngle(eventData.position);            float val = TouchJudge(currentPos, ref lastPos, Vector2.zero);            if (val > 0f && val <180f)            {                img.eulerAngles = new Vector3(0f,0f, -currentAngle + originAngle + selfAngle1);                model.eulerAngles = new Vector3(0f, 0f, -currentAngle + originAngle + selfAngle1);            }        }    }    public void OnEndDrag(PointerEventData eventData)    {        drag = false;    }    /// <summary>    /// 将屏幕坐标转成UI坐标    /// </summary>    /// <param name="pos1"></param>    /// <returns></returns>    float GetAngle(Vector2 pos1) {        Vector2 pos;        RectTransformUtility.ScreenPointToLocalPointInRectangle(parentRect, pos1, cam, out pos);        currentPos = pos;        return Mathf.Atan2(pos.x, pos.y) * Mathf.Rad2Deg;    }    /// <summary>    /// 判断顺时针还是逆时针旋转    /// </summary>    /// <param name="current"></param>    /// <param name="last"></param>    /// <param name="anchor"></param>    /// <returns></returns>    private float TouchJudge(Vector2 current, ref Vector2 last, Vector2 anchor)    {        Vector2 lastDir = (last - anchor).normalized;         Vector2 currentDir = (current - anchor).normalized;        float lastDot = Vector2.Dot(Vector2.right, lastDir);        float currentDot = Vector2.Dot(Vector2.right, currentDir);        float lastAngle = last.y < anchor.y              ? Mathf.Acos(lastDot) * Mathf.Rad2Deg              : -Mathf.Acos(lastDot) * Mathf.Rad2Deg;        float currentAngle = current.y < anchor.y            ? Mathf.Acos(currentDot) * Mathf.Rad2Deg            : -Mathf.Acos(currentDot) * Mathf.Rad2Deg;        last = current;        return currentAngle - lastAngle;    }}

canvas设置如下：

脚本赋值如下：