[LISP]求教：等高线交点为什么返回为空？

msi701 · 发表于 2004-6-5 14:33:00

请各位大哥帮忙看一下我的程序，为什么求交，没有返回的列表。要是有，请问怎么样让它们按横坐标排列？;================================================================
(vl-load-com)
(defun GetPlXY (ename fit    / en closeID    ptype i len v vn pl p isfit fittag hval)
(setq    en    (entget ename)
   ptype    (cdr (assoc 0 en))
   pl    nil
   fittag    (cdr (assoc 70 en))
   fittag    (if fittag fittag 0)
   isfit    (logand fittag 2)
   closeID    (logand fittag 1)
   hval    (cdr (assoc 38 en))
)
(if    (or (= ptype "LWPOLYLINE") (= ptype "POLYLINE"))
(progn
(setvar "useri1"    closeID )
(setvar "useri2"    isfit )
(if (null hval) (setq hval 9999))
(setvar "userr1"    hval )

(cond
(    (= ptype "LWPOLYLINE")
   (progn
(SETQ I 0 LEN (LENGTH EN))
(WHILE (< I LEN)
   (SETQ VN (LIST (NTH I EN)))
   (SETQ P (CDR (ASSOC 10 VN)))
   (IF P    (SETQ PL (CONS P PL)))
   (SETQ I (1+ I))
)
   )
   )
(    (= ptype "POLYLINE")
   (progn
   (setvar "useri2"    2 )
(setq v (entnext ename))
(setq vn (entget v))
(while (= (cdr (assoc 0 vn)) "VERTEX")
   (if (or fit (= 0    (cdr (assoc 70 vn))) ) ; (0 p)--- P is survey point
   (setq pl (cons (cdr (assoc 10 vn)) pl)) ; (1 p)----p is fit point
   )
   (setq v (entnext v))
   (setq vn (entget v))
); end while
   )
)
   ); end cond
   (setq pl (reverse pl) )
   (if (= 1 closeID) (setq pl (append pl (list (nth 0 pl)))))
))

pl

)
;;========================
;    Function Get_Interpoint
; Return: Point of Intersection Of Line & Polyline
;;========================
(Defun Get_IntersPoint (p1 p2 ename / pl i listlen intp_lst firstpoint secondpoint intp)
(setq p1 '(0 150) p2 '(1000 150))
(command "line" p1 p2"")
(setq T (ssget "x" '((0 . "line"))))
(setq pl (GetPlXY ename T))
(setq i 0 listlen (length pl))
(setq intp_lst nil)
(while (< i (1- listlen))
(setq firstpoint (nth i pl) secondpoint (nth (1+ i) pl))
(if (/= (setq intp (inters p1 p2 firstpoint secondpoint T)) nil)
(progn
(setq intp_lst (cons intp intp_lst))
))
(setq i (1+ i))
)
intp_lst
)
(princ)