unity 如何使用LineRenderer 动态划线

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>());

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
        }         
    }
}

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;
    } 
}