unity 如何使用LineRenderer 动态划线

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private LineRenderer line1;        
//画线
line1 = this.gameObject.AddComponent<LineRenderer>();
//只有设置了材质 setColor才有作用
line1.material = new Material(Shader.Find("Particles/Additive"));
line1.SetVertexCount(2);//设置两点
line1.SetColors(Color.yellow, Color.red); //设置直线颜色
line1.SetWidth(5f, 10f);//设置直线宽度      
//设置指示线的起点和终点
line1.SetPosition(0, A.transform.position);
line1.SetPosition(1, B.transform.position);
Destroy(this.gameObject.GetComponent<LineRenderer>());

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using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class PlayerTest : MonoBehaviour
{
    public GameObject clone;//这是个空物体  只添加了一个LineRenderer组件
    public float speed = 5;
    public float jumpSpeed = 10f;
    public float luodi = 15;
    private Vector3 movePos = Vector3.zero;
    public CharacterController controller;
    private LineRenderer line;
    Vector3[] path;
    private float time = 0;
    List<Vector3> pos=new List<Vector3> ();
    void Awake()
    {
              path = pos.ToArray();//初始化
              line = clone.GetComponent<LineRenderer>();//获得该物体上的LineRender组件
              line.SetColors(Color.blue, Color.red);//设置颜色
              line.SetWidth(0.2f, 0.1f);//设置宽度
    }
    void Update()
    {
        time += Time.deltaTime;
        if (time>0.1)//每0.1秒绘制一次
        {
            time = 0;
            pos.Add(transform.position);//添加当前坐标进链表
            path = pos.ToArray();//转成数组
        }
        if (controller.isGrounded)//判断人物是否落地
        {
            movePos = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
            movePos = transform.TransformDirection(movePos);
            movePos *= speed;
            if (Input.GetButton("Jump")) { 
                movePos.y = jumpSpeed;
              }
        }
        movePos.y -= luodi * Time.deltaTime;
        controller.Move(movePos * Time.deltaTime);
        if (path.Length!=0)//有数据时候再绘制
        {
            line.SetVertexCount(path.Length);//设置顶点数      
            line.SetPositions(path);//设置顶点位置
        }         
    }
}

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using System.Collections;
using System.Collections.Generic;
using UnityEngine; 
public class MouseTrack : MonoBehaviour
{ 
    /// <summary>
    /// 获取LineRenderer组件
    /// </summary>
    [Header("获得LineRenderer组件")]
    public LineRenderer lineRenderer;
    //获得鼠标跟踪位置
    private Vector3[] mouseTrackPositions = new Vector3[20]; 
    private Vector3 headPosition;   //头位置
    private Vector3 lastPosition;   //尾位置
    private int positionCount = 0;  //位置计数 
    [Header("设置多远距离记录一个位置")]
    public float distanceOfPositions = 0.01f;
    private bool firstMouseDown = false;    //第一次鼠标点击
    private bool mouseDown = false;     //鼠标点击 
    PolygonCollider2D polygonCollider;   //添加多边形碰撞 
    void Start()
    {
        polygonCollider = gameObject.GetComponent<PolygonCollider2D>();
    } 
    void Update()
    { 
        //鼠标点击的时候
        if (Input.GetMouseButtonDown(0))
        {
            polygonCollider.enabled = true;
            lineRenderer.positionCount = 20;
            firstMouseDown = true;
            mouseDown = true;
        }
        if (Input.GetMouseButtonUp(0))
        {
            mouseDown = false;
 
            //ClearColliderAndLineRenderer();
        }
        OnDrawLine();
        firstMouseDown = false;
    } 
    //画线
    private void OnDrawLine()
    {
        if (firstMouseDown == true)
        {
            positionCount = 0;
            //头坐标
            headPosition = Camera.main.ScreenToViewportPoint(Input.mousePosition + new Vector3(0, 0, 11));
            lastPosition = headPosition;
        } 
        if (mouseDown == true)
        {
            headPosition = Camera.main.ScreenToWorldPoint(Input.mousePosition + new Vector3(0, 0, 11));
            //判断头坐标到尾坐标的距离是否大于记录点位
            if (Vector3.Distance(headPosition, lastPosition) > distanceOfPositions)
            {
                //用于保存位置
                SavePosition(headPosition);
                positionCount++;
            }
            lastPosition = headPosition;
        } 
        //设置线性渲染器的位置
        SetLineRendererPosition(mouseTrackPositions);
    } 
    //保存位置
    private void SavePosition(Vector3 pos)
    {
        pos.z = 0;
        if (positionCount <= 19)
        {
            for (int i = positionCount; i < 20; i++)
            {
                mouseTrackPositions[i] = pos;
            }
        }
        else
        {
            for (int i = 0; i < 19; i++)
            {
                mouseTrackPositions[i] = mouseTrackPositions[i + 1];
            }
        }
        mouseTrackPositions[19] = pos;
 
        //创建碰撞路径
        List<Vector2> colliderPath = GetColliderPath(mouseTrackPositions);
        polygonCollider.SetPath(0, colliderPath.ToArray());
    } 
    //计算碰撞体轮廓
    float colliderWidth;
    List<Vector2> pointList2 = new List<Vector2>();
    List<Vector2> GetColliderPath(Vector3[] pointList3)
    {
        //碰撞体宽度
        colliderWidth = lineRenderer.startWidth;
        //Vector3转Vector2
        pointList2.Clear();
        for (int i = 0; i < pointList3.Length; i++)
        {
            pointList2.Add(pointList3[i]);
        } 
        //碰撞体轮廓点位
        List<Vector2> edgePointList = new List<Vector2>();
        //以LineRenderer的点位为中心, 沿法线方向与法线反方向各偏移一定距离, 形成一个闭合且不交叉的折线
        for (int j = 1; j < pointList2.Count; j++)
        {
            //当前点指向前一点的向量
            Vector2 distanceVector = pointList2[j - 1] - pointList2[j];
            //法线向量
            Vector3 crossVector = Vector3.Cross(distanceVector, Vector3.forward);
            //标准化, 单位向量
            Vector2 offectVector = crossVector.normalized;
            //沿法线方向与法线反方向各偏移一定距离
            Vector2 up = pointList2[j - 1] + 0.5f * colliderWidth * offectVector;
            Vector2 down = pointList2[j - 1] - 0.5f * colliderWidth * offectVector;
            //分别加到List的首位和末尾, 保证List中的点位可以围成一个闭合且不交叉的折线
            edgePointList.Insert(0, down);
            edgePointList.Add(up);
            //加入最后一点
            if (j == pointList2.Count - 1)
            {
                up = pointList2[j] + 0.5f * colliderWidth * offectVector;
                down = pointList2[j] - 0.5f * colliderWidth * offectVector;
                edgePointList.Insert(0, down);
                edgePointList.Add(up);
            }
        }
        //返回点位
        return edgePointList;
    } 
    //设置线条渲染器位置
    private void SetLineRendererPosition(Vector3[] position)
    {
        lineRenderer.SetPositions(position);
    } 
    //用于清除碰撞和线性渲染
    void ClearColliderAndLineRenderer()
    {
        if (polygonCollider)
        {
            polygonCollider.enabled = false;
        }
        lineRenderer.positionCount = 0;
    } 
}