Unity 实现画线火柴人核心画线功能

最近抖音上很火的小游戏，其中的核心划线功能。

 [SerializeField] private float width = 0.1f;
    [SerializeField] private Color color = Color.black;

    private LineRenderer line;
    private Vector2 previousPoint;

    private void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            //创建线条并渲染
            line = new GameObject("LineRenderer").AddComponent<LineRenderer>();
            line.material = new Material(Shader.Find("Sprites/Default")) { color = color };
            line.useWorldSpace = false;
            line.widthMultiplier = width;
       
            line.positionCount = 1;
            line.SetPosition(0, (Vector2)Camera.main.ScreenToWorldPoint(Input.mousePosition));

            //更新线条数据
            previousPoint = (Vector2)Camera.main.ScreenToWorldPoint(Input.mousePosition);
        }

        else if (Input.GetMouseButton(0))
        {
            if (previousPoint != (Vector2)Camera.main.ScreenToWorldPoint(Input.mousePosition))
            {
                //线条渲染更新
                line.positionCount++;
                line.SetPosition(line.positionCount - 1, (Vector2)Camera.main.ScreenToWorldPoint(Input.mousePosition));

                //增加碰撞器
                BoxCollider2D collider = new GameObject("BoxCollider2D").AddComponent<BoxCollider2D>();
                collider.transform.parent = line.transform;
                Vector2 latestPoint = (Vector2)Camera.main.ScreenToWorldPoint(Input.mousePosition);
                collider.transform.position = (previousPoint + latestPoint) * 0.5f;
                float angle = Mathf.Atan2((latestPoint - previousPoint).y, (latestPoint - previousPoint).x) * Mathf.Rad2Deg;
                collider.transform.eulerAngles = new Vector3(0, 0, angle);
                collider.size = new Vector2(Vector2.Distance(latestPoint, previousPoint), width);

                //更新数据
                previousPoint = (Vector2)Camera.main.ScreenToWorldPoint(Input.mousePosition);
            }
        }

        else if (Input.GetMouseButtonUp(0))
        {
            if (line.transform.childCount > 0)
            {
                //添加刚体
                line.gameObject.AddComponent<Rigidbody2D>().useAutoMass = true;
            }
        }
    }