在game窗口长按鼠标用LineRenderer画出鼠标移动轨迹

public class TestLineRenderer : MonoBehaviour
{
    public Material m;
    //当前在画的点
    private Vector3 nowPos;
    //画线组件
    private LineRenderer line;
    void Start()
    {
        //添加LineRenderer组件
        line = gameObject.AddComponent<LineRenderer>();
        //设置线的材质
        line.material = m;
        //设置线宽
        line.startWidth = 0.02f;
        line.endWidth = 0.02f;
        //设置最大点数
        line.positionCount = 0;
        //不让其首尾相连
        line.loop = false;
    }
    void Update()
    {
        DrawLine();
    }

    /// <summary>
    /// 画线
    /// </summary>
    void DrawLine()
    {
        //点击鼠标左键
        if (Input.GetMouseButton(0))
        {
            //加一个点
            line.positionCount += 1;
            //鼠标点击的屏幕坐标转世界坐标
            nowPos = Input.mousePosition;
            nowPos.z = 5;
            nowPos = Camera.main.ScreenToWorldPoint(nowPos);
            //画线
            line.SetPosition(line.positionCount-1, nowPos);
        }
    }
}