基于Unity3D ScrollRect的游戏摇杆实现

ScrollRect是UGUI提供的基础拖动组件，给它的Content绑定一个滑块就能工作了。如图

代码如下：

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

public class Example : ScrollRect {
    protected float mRadius = 0f;
    protected override void Start()
    {
        base.Start();
        mRadius = (transform as RectTransform).sizeDelta.x * 0.5f;
    }
    public override void OnDrag(PointerEventData eventData)
    {
        base.OnDrag(eventData);
        var contentPosition = this.content.anchoredPosition;
        if (contentPosition.magnitude > mRadius)
        {
            contentPosition = contentPosition.normalized * mRadius;
            SetContentAnchoredPosition(contentPosition);
        }
    }
    private void Update()
    {
        Debug.Log(content.anchoredPosition/ mRadius);
    }
}