;判断点是否在直线上(online 直线图元 点)
(defun online (en pt / ent pt1 pt2 l1 l2 l3 llist)
(setq ent (entget en))
(setq pt1 (cdr (assoc '10 ent)))
(setq pt2 (cdr (assoc '11 ent)))
(setq l1 (distance pt pt1))
(setq l2 (distance pt pt2))
(setq l3 (distance pt2 pt1))
(setq llist (vl-sort (list l1 l2 l3) '>))
(if (equal (car llist) (+ (cadr llist) (caddr llist)) 1e-6)
t
nil
)
)