UGUI简单实现炉石效果

主要达到效果：

1、箭头的指向，身体的长短

2、箭头的身体是不断向前流动的

3、箭头的头部以及尾部接近透明，并且在接入目标时会出现聚焦环

场景搭建：

创建脚本Arrow挂载在Canvas上，创建ArrowBody挂载在body上。

脚本：

Arrow:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

/// <summary>
/// 箭头的主题，用于控制箭头的显示、隐藏和指向
/// </summary>
public class Arrow : MonoBehaviour {

    Vector3 origin;         //起点
    public GameObject jiantou;  //箭头对象
    public GameObject ring;     //圆环
    public RectTransform rect;  //节点父组件

    GraphicRaycaster graphicRaycaster;
    EventSystem eventSystem;

    List<RaycastResult> list = new List<RaycastResult>();
    void Start () {
        graphicRaycaster = GetComponent<GraphicRaycaster>();

    }

	void Update () {

        PointerEventData eventData = new PointerEventData(eventSystem);//与指针（鼠标/触摸）事件相关的事件负载。(PointerEventData)
        eventData.pressPosition = Input.mousePosition;
        eventData.position = Input.mousePosition;//当前指针位置。
        graphicRaycaster.Raycast(eventData, list);//如同Physics.Raycast(ray, out hit)绑定相应的射线检测信息

        //点下鼠标左键
        if (Input.GetMouseButtonDown(0))
        {
            origin = Input.mousePosition;
            jiantou.transform.position = Input.mousePosition;
            
            if (list.Count > 0)
            {
                foreach (RaycastResult result in list)
                {
                    if (result.gameObject.tag == "target")
                    {
                        jiantou.SetActive(true);
                    }
                }
            }

        }

        //一直按住鼠标左键
        if (Input.GetMouseButton(0))
        {
            jiantou.transform.up = (Input.mousePosition - origin);
            jiantou.transform.position = Input.mousePosition;
            rect.sizeDelta = new Vector2(rect.rect.width, Vector3.Distance(Input.mousePosition, origin));

            if (list.Count > 0)
            {
                foreach (RaycastResult result in list)
                {
                    if (result.gameObject.tag == "self")
                    {
                        ring.SetActive(true);
                    }
                    else
                    {
                        ring.SetActive(false);
                    }
                }
            }
            else
            {
                ring.SetActive(false);
            }

        }

        //释放鼠标左键
        if (Input.GetMouseButtonUp(0))
        {
            list.Clear();
            ring.SetActive(false);
            jiantou.SetActive(false);
        }
    }
}

ArrowBody:

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

/// <summary>
/// 箭头的身体，主要用于控制箭头身体中节点的移动和透明度
/// </summary>
public class ArrowBody : MonoBehaviour {

    int numIndex;
    RectTransform localTransform;
    [Range(20,1000)]
    public float flowSpeed = 10f;   //流动速度
    /// <summary>
	/// 临时的Node节点
	/// </summary>
	Transform tempNodeTfm;
    void Start () {
        localTransform = GetComponent<RectTransform>();

    }
	
	void Update () {

        for (int i = 0; i < transform.childCount; i++)
        {
            tempNodeTfm = transform.GetChild(i);
            tempNodeTfm.localPosition = new Vector3(0, tempNodeTfm.localPosition.y + Time.fixedDeltaTime * flowSpeed, 0);
            numIndex = (int)localTransform.rect.height / 80;

            //箭头体内子节点的透明度显示
            if (i <= numIndex * 0.3f)
            {
                tempNodeTfm.GetComponent<Image>().color = Color.Lerp(tempNodeTfm.GetComponent<Image>().color, new Color(1, 1, 1, (70 * i + 60) / 255f), Time.fixedDeltaTime * 6f);
            }
            else if (i >= numIndex * 0.7f)
            {
                tempNodeTfm.GetComponent<Image>().color = Color.Lerp(tempNodeTfm.GetComponent<Image>().color, new Color(1, 1, 1, (70 * (numIndex - i) + 60) / 255f), Time.fixedDeltaTime * 6f);
            }
            else
            {
                tempNodeTfm.GetComponent<Image>().color = Color.white;
            }

            //箭头体内子节点的循环移动
            if (tempNodeTfm.localPosition.y > 40)
            {
                tempNodeTfm.localPosition = new Vector3(0, transform.GetChild(transform.childCount - 1).localPosition.y - 80, 0f);
                tempNodeTfm.SetAsLastSibling();

            }
        }

    }
}

效果：

参考：https://blog.csdn.net/qq_26276097/article/details/75453351