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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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