RaycastHit2D hit2D 
	= Physics2D.Raycast(transform.position, transform.right, sightDis);

在这种情况下sightDis根本不起作用，太坑了，必须要有层级才行…

public LayerMask layer;

RaycastHit2D hit2D 
	= Physics2D.Raycast(transform.position, transform.right, sightDis, layer);