[Unity实战]屏幕追踪显示目标

参考链接：http://www.manew.com/thread-48125-1-1.html?_dsign=4edc9052

效果图：



using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public enum BeaconMoveType
{
Rect, //矩形
Rllipse, //椭圆
}

public class Beacon : MonoBehaviour {

private Transform player;
private Transform target;
private List<GameObject> targetList = new List<GameObject>();

private float width;
private float height;
public float range = 5f;//在范围内就不显示，否则显示
public BeaconMoveType beaconMoveType;

public void SetTarget(Transform target)
{
this.target = target;
}

public void SetTarget()
{
if (targetList.Count > 0)
{
targetList.Sort((a, b) =>
{
float disA = MathTool.GetDistance(a.transform, player);
float disB = MathTool.GetDistance(b.transform, player);
return disA.CompareTo(disB);
});

float dis = MathTool.GetDistance(targetList[0].transform, player);
if (dis > range) target = targetList[0].transform;
else target = null;
}
}

void Start ()
{
player = CharacterManager.Instance.player.transform;
targetList = CharacterManager.Instance.enemyCampGo;
//因为描点默认为中心，所以UI的移动范围为：
//x:-Screen.width / 2 - Screen.width / 2
//y:-Screen.height / 2 - Screen.height / 2
//50是偏移量
width = Screen.width / 2 - 50;
height = Screen.height / 2 - 50;
}

void Update ()
{
SetTarget();
if ((player == null) || (target == null))
{
transform.localScale = Vector3.zero;//隐藏
return;
}
else
{
transform.localScale = Vector3.one;//显示
}

Vector3 dir = (target.position - player.position).normalized;
dir.y = 0;
float dot = Vector3.Dot(dir, Vector3.forward);//以Vector3.forward为基准
float angle = Mathf.Acos(dot) * Mathf.Rad2Deg;
Vector3 cross = Vector3.Cross(dir, Vector3.forward);//判断左右

//Debug.Log("角度：" + angle + "---" + (cross.y > 0?"左边":"右边"));
transform.rotation = Quaternion.Euler(new Vector3(0, 0, angle * (cross.y > 0 ? 1 : -1)));

Vector3 pos = Vector3.zero;
if (angle == 0) pos = new Vector3(0, height, 0);
else if (angle == 180) pos = new Vector3(0, -height, 0);
else
{
//1.椭圆方程
//焦点在x轴：x²/a²+ y²/b²=1 (a>b>0)
//焦点在y轴：y²/a²+ x²/b²=1 (a>b>0)
//2.k = x / y
//k在0-90度时大于0，90-180度时小于0

float k = Mathf.Tan(angle * Mathf.Deg2Rad);
k = Mathf.Abs(k);//排除符号的影响

switch (beaconMoveType)
{
case BeaconMoveType.Rllipse:
pos.y = width * height * Mathf.Sqrt((1f / (width * width + height * height * k * k)));
pos.x = pos.y * k;
if (angle > 90f) pos.y = -pos.y;//目标在背后
if (cross.y > 0f) pos.x = -pos.x;//目标在左边
break;
case BeaconMoveType.Rect:
pos.x = height * k;
if ((pos.x > -width) && (pos.x < width))//在矩形区域的上边或者下边
{
pos.y = height;
}
else//在矩形区域的左边或者右边
{
pos.x = width;
if(k != 0f) pos.y = pos.x / k;
}
if (angle > 90f) pos.y = -pos.y;//目标在背后
if (cross.y > 0f) pos.x = -pos.x;//目标在左边
break;
default:
break;
}
}

transform.localPosition = pos;
}
}