Unity摇杆制作的方法

using System;
using UnityEngine;
using UnityEngine.EventSystems;

public class PEListener : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IDragHandler
{
    public Action<PointerEventData> onClickDown;//鼠标按下时触发的事件
    public Action<PointerEventData> onClickUp;//鼠标抬起时触发的事件
    public Action<PointerEventData> onClickDrag;//鼠标按下时触发的事件
    public void OnPointerDown(PointerEventData eventData)
    {
        if (onClickDown != null)
        {
            onClickDown(eventData);
        }
    }
    public void OnPointerUp(PointerEventData eventData)
    {
        if (onClickUp != null)
        {
            onClickUp(eventData);
        }
    }
   
    public void OnDrag(PointerEventData eventData)
    {
        if (onClickDrag!=null)
        {
            onClickDrag(eventData);
        }
    }
  
}

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class Test : MonoBehaviour {

    //轮盘UI
    public Image imageTough;//轮盘触摸区域
    public Image imgDir;//轮盘背景
    public Image imaPoint;//轮盘操作点


    
    //轮盘相关数据
    Vector2 startPos;//轮盘按下的坐标
    Vector2 defulPos;//轮盘按下的坐标
    float poinDis=90;// 轮盘中心和边缘的最大距离（数据自己测试）


   private void Start()
    {
        defulPos = imageTough.transform.position;

        //由于我们的Canvas选择的是Scale with Screen Size,且Match为1，也就是UI缩放受高度影响到大，具体数据见下图
        //poinDis实际大小=poinDis *缩放
        poinDis = Screen.height * 1.0f / 1334 * poinDis;
    }
}

using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class Test : MonoBehaviour {

    //轮盘UI
    public Image imageTough;//轮盘触摸区域
    public Image imgDir;//轮盘背景
    public Image imaPoint;//轮盘操作点


    
    //轮盘相关数据
    Vector2 startPos;//轮盘按下的坐标
    Vector2 defulPos;//轮盘按下的坐标
    float poinDis=90;// 轮盘中心和边缘的最大距离（数据自己测试）


    private void Start()
    {
        defulPos = imageTough.transform.position;

        //由于我们的Canvas选择的是Scale with Screen Size,且Match为1，也就是UI缩放受高度影响到大，具体数据见下图
        //poinDis实际大小=poinDis *缩放
        poinDis = Screen.height * 1.0f / 1334 * poinDis;


        RegisterTouchEvts();
    }


    public void RegisterTouchEvts()
    {
        PEListener lister = imageTough.gameObject.AddComponent<PEListener>();

        lister.onClickDown = (PointerEventData evt) =>
        {
            //鼠标按下时设置轮盘背景位置
            startPos = evt.position;
            imgDir.transform.position = evt.position;

        };

        lister.onClickUp = (PointerEventData evt) =>
        {
            //鼠标抬起时设置轮盘背景位置和轮盘操作点为默认位置
            
            imgDir.transform.position = defulPos;
            imaPoint.transform.localPosition = Vector2.zero;

        };

        lister.onClickDrag = (PointerEventData evt) =>
        {

            //计算是否超过轮盘中心和边缘的最大距离
            Vector2 dir = evt.position - startPos;
            float len = dir.magnitude;

            //超过了，限制为最大位置
            if (len > poinDis)
            {
                Vector2 clampDir = Vector2.ClampMagnitude(dir, poinDis);
                imaPoint.transform.position = startPos + clampDir;
            }
            else
            {
                imaPoint.transform.position = evt.position;
            }
        };
    }

}