准备素材
需要一个背景图片,和一个stick
实现原理
1.Stick跟随手指按下进行滑动,需要用到屏幕坐标转UI坐标。然后如果pos超过了圆的半径,需要将UI的Pos限制一下。
RectTransformUtility.ScreenPointToLocalPointInRectangle
2.Stick监听滑动和滑动结束事件,滑动结束回到原点。注意是Add New Event Type。而不是在一个Event Type里添加两个监听
3.最后可以将pos归一化处理得到一个Vector2值,返回给游戏处理移动
相关代码
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class JoyStick : MonoBehaviour {
private Canvas cs;
public Transform stick;
//滑动的半径
public float max_R = 80;
private Vector2 touch_dir = Vector2.zero;
public Vector2 dir {
get {
return this.touch_dir;
}
}
// Use this for initialization
void Awake () {
this.cs = GameObject.Find("Canvas").GetComponent<Canvas>();
this.stick.localPosition = Vector2.zero;
this.touch_dir = Vector2.zero;
}
// Update is called once per frame
void Update () {
if (this.touch_dir.x == 0 && this.touch_dir.y == 0) {
return;
}
Debug.Log(touch_dir);
EventMgr.Instance.Emit("JoyStick", this.touch_dir);
}
public void OnStickDrag() {
Vector2 pos = Vector2.zero;
//屏幕坐标转UI坐标
RectTransformUtility.ScreenPointToLocalPointInRectangle(this.transform as RectTransform,
Input.mousePosition, this.cs.worldCamera, out pos);
//拖拽的半径
float len = pos.magnitude;
if (len <= 0) {
this.touch_dir = Vector2.zero;
return;
}
// 归一化,
this.touch_dir.x = pos.x / len; // cos(r)
// this.touch_dir.y = pos.y / len; // (sinr) cos^2 + sin ^ 2 = 1;
if (len >= this.max_R) { // this.max_R / len = x` / x = y` / y;
pos.x = pos.x * this.max_R / len;
pos.y = pos.y * this.max_R / len;
}
Debug.Log("OnStickDrag:"+pos);
this.stick.localPosition = pos;
}
public void OnStickEndDrag() {
this.stick.localPosition = Vector2.zero;
this.touch_dir = Vector2.zero;
EventMgr.Instance.Emit("JoyStick", this.touch_dir);
}
}