Unity实现简单摇杆的制作

using UnityEngine;
using UnityEngine.EventSystems;
using System.Collections;
public class JoyStick : MonoBehaviour, IDragHandler, IEndDragHandler, IBeginDragHandler
{
    public static float h, v;  //传出hv
    public float maxDis;    //最大距离
 
    private RectTransform childRectTrans;
    private Coroutine coroutine = null;
 
    void Start()
    {
        childRectTrans = transform.GetChild(0) as RectTransform;
    }
    public void OnBeginDrag(PointerEventData eventData)
    {
        if (coroutine != null)
        {
            StopCoroutine(coroutine);
            coroutine = null;
        }
    }
    public void OnDrag(PointerEventData eventData)
    {
        Vector3 outPos;
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(this.transform as RectTransform, eventData.position, eventData.pressEventCamera, out outPos))
        {
            childRectTrans.position = outPos;
 
            //限制拖拽距离
            childRectTrans.anchoredPosition = Vector2.ClampMagnitude(childRectTrans.anchoredPosition, maxDis);
 
            //或者利用子物体和父物体的距离判断是否超过最大距离，当距离大于等于最大的距离时候，
            //计算父物体和子物体的向量，然后利用向量*最大距离来限制拖拽距离
            //if (Vector2.Distance(childRectTrans.position, this.transform.position) > maxDis)
            //{
            //    Vector2 dir = (childRectTrans.position - this.transform.position).normalized;
            //    childRectTrans.anchoredPosition = dir * maxDis;
            /