LineRenderer屏幕绘制

public class Controller : MonoBehaviour
{
    //划线
    public float z;
    private LineRenderer lineRenderer;
    private bool isMouseDown;
    private Vector3 leftUpPoint;
    private Vector3 rightUpPoint;
    private Vector3 leftDownPoint;
    private Vector3 rightDownPoint;


    // Start is called before the first frame update
    void Start()
    {
        lineRenderer = this.GetComponent();
    }

    // Update is called once per frame
    void Update()
    {
        SelSoldier();
    }

    /// 

    /// 划线 框选士兵
    /// 
    private void SelSoldier()
    {
        if (Input.GetMouseButtonDown(0))
        {
            isMouseDown = true;
            leftUpPoint = Input.mousePosition;
        }
        else if (Input.GetMouseButtonUp(0))
        {
            isMouseDown = false;
            //取消绘制
            lineRenderer.positionCount = 0;
        }

        if (isMouseDown)
        {
            rightDownPoint = Input.mousePosition;
            leftUpPoint.z = z;
            rightDownPoint.z = z;
            leftDownPoint = new Vector3(leftUpPoint.x,rightDownPoint.y,z);
            rightUpPoint = new Vector3(rightDownPoint.x,leftUpPoint.y,z);

            lineRenderer.positionCount = 4;
            lineRenderer.SetPosition(0,Camera.main.ScreenToWorldPoint(leftUpPoint));
            lineRenderer.SetPosition(1,Camera.main.ScreenToWorldPoint(rightUpPoint));
            lineRenderer.SetPosition(2, Camera.main.ScreenToWorldPoint(rightDownPoint));
            lineRenderer.SetPosition(3,Camera.main.ScreenToWorldPoint(leftDownPoint));
        }
    }
}