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unity 2d 箭头追踪

unity 2d 箭头追踪

作者: Albert_d37d | 来源:发表于2021-09-16 11:26 被阅读0次

using System.Collections;

using System.Collections.Generic;

using UnityEngine;

using UnityEngine.UI;

using System;

public class ArrowsManager : MonoBehaviour

{

    private GameObject m_arrows;

    private Vector3 m_Screen_Center;

    private void Start()

    {

        m_Screen_Center = new Vector3(Screen.width / 2, Screen.height / 2, 0);

        m_arrows = GameObject.Find("Canvas/Arrows");

        InitArrowsColor();

    }

    void Update()

    {

        if (!GameManager.GetInst().m_bStart) return;

        ReflushArrows();       

    }

    private void ReflushArrows()

    {

        for(int i = 0;i < GameManager.GetInst().m_groupManager.m_listEnemyGroup.Count;i++)

        {

            Group group = GameManager.GetInst().m_groupManager.m_listEnemyGroup[i];

            string str = Enum.GetName(typeof(E_ClothesType), group.m_clothesType);         

            Transform tfArrow = m_arrows.transform.Find(str);         

            tfArrow.gameObject.SetActive(!IsInScreen(group.transform));

            SetLookAt(tfArrow.GetComponent<RectTransform>(), group.transform);

            //设置距离数值

            float distance = Vector3.Distance(group.transform.position, GameManager.GetInst().m_groupManager.m_playerGroup.transform.position);

            tfArrow.GetChild(0).GetComponent<Text>().text = (int)distance + "m";

            SetEdge(tfArrow);

        }

    }

    //设置到屏幕边缘

    private void SetEdge(Transform tf)

    {

        Vector3 CachePosion = tf.right * (Screen.width > Screen.height ? Screen.width - 100 : Screen.height - 100);

        CachePosion.x = Mathf.Clamp(CachePosion.x, -Screen.width / 2 + 100, Screen.width / 2 - 100);

        CachePosion.y = Mathf.Clamp(CachePosion.y, -Screen.height / 2 + 100, Screen.height / 2 - 100);

        tf.GetComponent<RectTransform>().anchoredPosition3D = CachePosion;

    }

    private void SetLookAt(RectTransform arrow,Transform target)

    {

        //将目标的世界坐标转换成屏幕坐标

        Vector3 target_ScreenPoint = Camera.main.WorldToScreenPoint(target.position);

        //计算target_ScreenPoint和屏幕中心点的绝对值角度

        float angle = Mathf.Atan(Mathf.Abs(target_ScreenPoint.y - Screen.height / 2)

            / Mathf.Abs(target_ScreenPoint.x - Screen.width / 2)) * 180 / Mathf.PI;

        //通过判断target_ScreenPoint相对屏幕中心点所在象限处理angle的差值

        if (target_ScreenPoint.x <= Screen.width / 2)

            angle = target_ScreenPoint.y >= Screen.height / 2 ? 90 - angle : 90 + angle;

        else

            angle = target_ScreenPoint.y >= Screen.height / 2 ? 270 + angle : 270 - angle;

        #region 计算摄像机和目标的叉乘

        //以屏幕中心所在的单位向量为起始向量from,并将from的y值设成和目标y值保持一致

        Vector3 from = Camera.main.transform.forward;

        from.y = target.forward.y;

        //将屏幕中心坐标转换成世界坐标

        Vector3 cameraPos = Camera.main.ScreenToWorldPoint(m_Screen_Center);

        cameraPos.y = target.position.y;

        //求出目标点与摄像机之间的向量

        Vector3 to = target.position - cameraPos;

        //求出两向量之间的叉乘

        Vector3 cross = Vector3.Cross(from, to);

        #endregion

        //根据叉乘求出带符号的角度

        //cross.y > 0:目标向量位于起始向量右侧

        //cross.y < 0:目标向量位于起始向量左侧

        if (cross.y > 0 && angle < 180)

            angle += 180;

        else if (cross.y < 0 && angle > 180)

            angle -= 180;

        Vector3 euler = arrow.eulerAngles;

        euler.z = angle;

        //设置箭头的角度

        arrow.eulerAngles = euler;

    }

    private bool IsInScreen(Transform tf)

    {

        Vector2 vt2 = ToScreenPos(tf);     

        if(vt2.x > 0 && vt2.y > 0 && vt2.x < Screen.width && vt2.y < Screen.height)

        {

            return true;

        }

        return false;

    }

    private Vector2 ToScreenPos(Transform tf)

    {

        return Camera.main.WorldToScreenPoint(tf.position);

    }

    private void InitArrowsColor()

    {

        for(int i = 0;i < m_arrows.transform.childCount;i++)

        {

            Transform child = m_arrows.transform.GetChild(i);         

            E_ClothesType type = (E_ClothesType)Enum.Parse(typeof(E_ClothesType), child.name);         

            child.GetComponent<Image>().color = Utils.GetColor(type);

        }

    }

}

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