Unity实现简单虚拟摇杆实现简单虚拟摇杆
最近一直在倒腾用UGUI做虚拟摇杆，网上普遍的的做法就是使用以下的代码，但是这个有些注意事项，第一点就是Canvas的
Render Mode必须是Screen Space Overlay，第二点就是挂载这个脚本的锚点的x,y必须是0.5，如图下：
using UnityEngine;
using UnityEngine.EventSystems;
public class JoyStick : MonoBehaviour, IDragHandler, IEndDragHandler
{
Transform point;
Vector3 startPos;//开始位置
Vector3 dir;//方向
float radius = 0;//需要移动的半径
void Start()
{
point = transform.GetChild(0);
radius = (transform as RectTransform).sizeDelta.x * 0.5f;
startPos = point.position;
}
public void OnDrag(PointerEventData eventData)
{
point.position = eventData.position;
dir = (point.position - startPos).normalized;
if (Vector3.SqrMagnitude(point.position - startPos) > radius * radius)
point.position = startPos + dir * radius;
}
public void OnEndDrag(PointerEventData eventData)
{
point.localPosition = Vector3.zero;
}
}
如果Canvas的Render Mode是Screen Space Camera，这样的话上面的代码是不能满足要求的，花了一点时间才发现是这个
原因，导致上面的代码不适用的，最后把代码重写了一下，终于可以成功了！
public class JoyStick : MonoBehaviour, IDragEvent
{
private Canvas canvas;
private RectTransform rectTransform;//坐标
private static Quaternion amendAngle;
private static float mRadius = 0,v=0, h=0;
private static Transform point;
private static Vector3 initPos;
private static Vector2 startPos;
private void Start()
{
point = transform.GetChild(0);
canvas = GameObject.Find("UIRoot").GetComponent<Canvas>();
rectTransform = transform as RectTransform; //也可以写成this.GetComponent<RectTransform>(),但是不建议；
mRadius = (transform as RectTransform).sizeDelta.x * 0.5f;
initPos = point.localPosition;
h = v = 0;
}
public void OnBeginDrag(PointerEventData eventData)
{
RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, eventData.position, canvas.worldCamera, out
startPos);
startPos = eventData.position - startPos;
h = v = 0;
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