2017-10-19

Unity3D开发(四)

Unity3d实现目标追踪

前言

在合金装备5 幻痛中玩家可以自己定义目标地点，标记会显示目标与玩家的大致方向和距离

Unity实现

使用两个脚本来实现目标追踪 CreatMark.cs 挂载在想要追踪的目标身上

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CreatMark : MonoBehaviour {
    
    //自己定义一个UGUI的image并在其中添加text文本用来显示距离
    public GameObject mark;
    //确保场景中存在UGUI的根节点
    private GameObject canvans;
	// Use this for initialization
	void Start () {
        canvans = GameObject.Find("Canvas");
        GameObject g = Instantiate(mark);
        //sendmessage传递当前脚本的载体的Transform
        g.SendMessage("getTarget",transform);
        g.transform.SetParent(canvans.transform);
	}
	
}

CArrowLookAt.cs用来控制目标追踪UI


using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class CArrowLockAt : MonoBehaviour
{
    public Transform target;    //目标  
    public Transform self;  //自己  
    public Text text;
    
    public float direction; //箭头旋转的方向，或者说角度，只有正的值  
    public Vector3 u;   //叉乘结果，用于判断上述角度是正是负  
    float devValue = 10f;   //离屏边缘距离  
    float showWidth;    //由devValue计算出从中心到边缘的距离（宽和高）  
    float showHeight;
    
    // 初始化  
    void Start()
    {
        //获取标记上的文本组件
        text = gameObject.GetComponentInChildren<Text>();
        
        //  获取主摄像机的Transform
        self =  GameObject.Find("PlayerCamera").GetComponent<Transform>();
        
        showWidth = transform.parent.GetComponent<RectTransform>().rect.width / 2 - devValue;
        showHeight = transform.parent.GetComponent<RectTransform>().rect.height / 2 - devValue;
    }
    void Update()
    {
        if (target)
        {
            //更新距离
            if (Time.frameCount % 10 == 0)
                if (target && self)
                {
                    text.text = (int)Vector3.Distance(target.transform.position, self.transform.position) + "m";
                }
            // 每100帧都重新计算一次  
            if (Time.frameCount % 100 == 0)
            {
                showWidth = transform.parent.GetComponent<RectTransform>().rect.width / 2 - devValue;
                showHeight = transform.parent.GetComponent<RectTransform>().rect.height / 2 - devValue;
            }
  
            // 计算向量和角度  
            Vector3 forVec = self.forward;  //计算本物体的前向量  
            Vector3 angVec = (target.position - self.position).normalized;  //本物体和目标物体之间的单位向量  
            Vector3 targetVec = Vector3.ProjectOnPlane(angVec - forVec, forVec).normalized; //这步很重要，将上述两个向量计算出一个代表方向的向量后投射到本身的xy平面  
            Vector3 originVec = self.up;
            direction = Vector3.Dot(originVec, targetVec);  //再跟y轴正方向做点积和叉积，就求出了箭头需要旋转的角度和角度的正负  
            u = Vector3.Cross(originVec, targetVec);
            direction = Mathf.Acos(direction) * Mathf.Rad2Deg;  //转换为角度  
            u = self.InverseTransformDirection(u);  //叉积结果转换为本物体坐标  
            // 给与旋转值  
            //transform.rotation = originRot * Quaternion.Euler(new Vector3(0f, 0f, direction * (u.z > 0 ? 1 : -1)));
            // 计算当前物体在屏幕上的位置  
            Vector2 screenPos = Camera.main.WorldToScreenPoint(target.position);
            //if(Vector3.Dot(forVec, angVec) < 0)  
            // 不在屏幕内的情况  
            if (screenPos.x < devValue || screenPos.x > Screen.width - devValue || screenPos.y < devValue || screenPos.y > Screen.height - devValue || Vector3.Dot(forVec, angVec) < 0)
            {
                Vector3 result = Vector3.zero;
                if (direction == 0) //特殊角度0和180直接赋值，大家知道tan90会出现什么结果  
                {
                    result.y = showHeight;
                }
                else if (direction == 180)
                {
                    result.y = -showHeight;
                }
                else    //非特殊角  
                {
                    // 转换角度  
                    float direction_new = 90 - direction;
                    float k = Mathf.Tan(Mathf.Deg2Rad * direction_new);
                    // 矩形  
                    result.x = showHeight / k;
                    if ((result.x > (-showWidth)) && (result.x < showWidth))    // 角度在上下底边的情况  
                    {
                        result.y = showHeight;
                        if (direction > 90)
                        {
                            result.y = -showHeight;
                            result.x = result.x * -1;
                        }
                    }
                    else    // 角度在左右底边的情况  
                    {
                        result.y = showWidth * k;
                        if ((result.y > -showHeight) && result.y < showHeight)
                        {
                            result.x = result.y / k;
                        }
                    }
                    if (u.z > 0)
                        result.x = -result.x;
                }
               
                    transform.localPosition = result;
               
            }
            else    // 在屏幕内的情况  
            {
                transform.position = screenPos;
            }
        }
        else
        {
           //标记被清除时销毁自身
           Destroy(gameObject);
             
        }
    }
    //获取目标的Transform组件 创建该GameObject时在 CreatMark 中调用
    public void getTarget(Transform t)
    {
        target = t;
        Vector3 t2 = new Vector3(0,0,0);
        t2 = t.position;
        //对于新增的标记将y轴坐标增大到玩家视线平面
        if (t2.y <= 0)
            t2.y += 33;
        target.position = t2;
    }
}