直线段和多段线。

cheefeel

求教有了多段线的存在，直线段存在的意义为何？
就这么简单的问题。

mokson

因为简单而存在。

1291500406

  直线只能是直线，而多段线可以是直线与曲线，例如弧线的联合体。

直线的线宽是一样的，但是多段线的线宽可以一样，也可以不一样，可以调整开始线宽和末尾线宽使多段线的粗细不一致。

多段线闭合之后可以拉伸建立为三维实体，直线即使闭合也不可以拉伸。

直线画出来都是单一的个体

多段线一次性画出来的都是一个整体

用直线功能不能画出多段线,用直线画出连续的线段后可以组合成多段线,

也可以分解功能将多段线分解成单一的直线

多段线转成直线 x命令即可   

圆弧转成多段线(defun c:bb(/ bb) (command "pedit" "M" (ssget '((0 . "ARC"))) "" "Y" "")(princ)) x命令却变成了 圆弧

直线转成多段线(defun c:bb (/ b)(setvar "peditaccept"  1)(command "pedit" "m"  (ssget '((0 . "LINE"))) "" "j"  "0" "" )(setvar "peditaccept"  0)(princ))

椭圆转化为样条曲线(defun C:bb(/ E E1 E2 O)(setq E (car (entsel "\n必强提示选择椭圆转化为样条曲线: ")))(setq O (vlax-ename->vla-object E))(vla-offset O 0.1)

(setq E1 (entlast))(vla-offset (vlax-ename->vla-object E1) -0.1)(setq E2 (entlast))(entdel E)(entdel E1)(princ))

;;;椭圆转化为多段线
(defun c:bb (/ ss n)(setq n 0)(if (setq ss (ssget '((0 . "ELLIPSE"))))(progn(command "_.undo" "_begin")(repeat (sslength ss)(ellipse->polyline (ssname ss n))(setq n (1+ n)))(command "_.undo" "_end")))(princ (strcat "\n\t" (itoa n) " ellipse(s) convertie(s) en polyligne(s)."))(princ))

                           ;;;

绘制多段线椭圆

(defun c:bb (/ *error* ec pe old ent)
(defun *error* (msg)(if (= msg "Fonction annulée")(princ)(princ (strcat "\nErreur: " msg)))(setvar "cmdecho" ec)(setvar "pellipse" pe)(princ))(setq ec  (getvar "cmdecho")pe  (getvar "pellipse")old (entlast))(setvar "cmdecho" 1)(setvar "pellipse" 0)(command "_.ellipse")(while (/= 0 (getvar "cmdactive"))(command pause))(if (not (eq old (setq ent (entlast))))(ellipse->polyline ent))(setvar "cmdecho" ec)(setvar "pellipse" pe)(princ))
(defun ellipse->polyline (ent / elst ucs os ec pe cen ext pa1 pa2 grd prd ang pt1 pt2 mat line ed)(setq elst (entget ent))(or(equal (trans '(0 0 1) 1 0 T) (cdr (assoc 210 elst)) 1e-9)(and(setq ucs T)
(command "_.ucs" "_zaxis" '(0 0 0) (trans (cdr (assoc 210 elst)) ent 1 T))))(setq ec   (getvar "cmdecho") pe   (getvar "pellipse")  elst (entget ent) cen  (cdr (assoc 10 elst))  elv  (caddr (trans cen 0 (cdr (assoc 210 elst)))) ext  (trans (mapcar '+ cen (cdr (assoc 11 elst))) 0 1) cen  (trans cen 0 1)  pa1  (cdr (assoc 41 elst)) pa2  (cdr (assoc 42 elst)) grd  (distance cen ext) prd  (* grd (cdr (assoc 40 elst))) ang  (angle cen ext))(entdel ent)(setvar "cmdecho" 0)(setvar "pellipse" 1)(command "_.ellipse" "_c" "_non" cen "_non" (polar cen ang grd) prd)(if (or (/= pa1 0.0) (/= pa2 (* 2 pi)))(progn (setq ent (entlast)pt1 (list (* grd (cos pa1)) (* prd (sin pa1))) pt2 (list (* grd (cos pa2)) (* prd (sin pa2))) mat (list (list (cos ang) (- (sin ang)) 0) (list (sin ang) (cos ang) 0)  '(0 0 1)) pt1 (mapcar '+ cen (mxv mat pt1)) pt2 (mapcar '+ cen (mxv mat pt2)))
(command "_.line" "_non" pt1 "_non" pt2 "") (setq line (entlast))(cond ((equal ext pt2 1e-9)(command "_.break" ent "_non" pt1 "_non" pt1)(entdel (entnext line))) ((equal ext pt1 1e-9) (command "_.break" ent "_non" pt2 "_non" pt2)(entdel (entlast))) ((< (atof (angtos pa2)) (atof (angtos pa1)))(setq ed (getvar "EDGEMODE")) (setvar "EDGEMODE" 1)(command "_.trim" line "" (polar cen (+ ang pi) grd) "")(setvar "EDGEMODE" ed)(command "_.pedit" (entlast) "_j" (entnext line) "" ""))(T(setq ed (getvar "EDGEMODE"))(setvar "EDGEMODE" 1)(command "_.trim" line "" ext "")(setvar "EDGEMODE" ed)))(entdel line)))(command "_.convert" "_p" "_s" (entlast) "")(and ucs (command "_.ucs" "_previous"))(setvar "cmdecho" ec)(setvar "pellipse" pe))
(defun mxv (m v)(mapcar (function (lambda (r) (apply '+ (mapcar '* r v)))) m)) x命令也变成 了圆弧

;;;圆转化为多段线

(defun gps->Circle-2plinelst (pt r n / ang nang pt1 ptlst)(setq nang (/ (* 2 pi) n) ang 0)(repeat n(setq pt1 (polar pt ang r))(setq ang (+ ang  nang))(setq ptlst (append ptlst (list pt1)))))

(defun gps->entmake-pline(pt_lst lay clsd)(entmakex (append(list '(0 . "LWPOLYLINE") '(100 . "AcDbEntity") '(100 . "AcDbPolyline")  (cons 8 lay)(cons 90 (length pt_lst))(cons 70 clsd))
(mapcar '(lambda (pt) (cons 10 pt)) pt_lst))))
(defun gps->ss-2lst (ss / lst n)  (if (= (type ss) 'PICKSET)(repeat (setq n (sslength ss))(setq lst (cons (ssname ss (setq n (1- n))) lst))))lst)
(defun c:bb  (if (null $fs)(setq $fs 10))    (setq tmp 360) (if tmp (setq $fs tmp))  (foreach n (gps->ss-2lst (ssget '((0 . "Circle"))))
(setq ptlst (entget n) lay (cdr (assoc 8 ptlst))  pt (cdr (assoc 10 ptlst)) r (cdr (assoc 40 ptlst)))(gps->entmake-pline (gps->Circle-2plinelst pt r $fs) lay 1)(entdel n)  )  (princ))

;;;将所有图元转化为直线

(defun c:bb(/ dist dist_pd i leng name name_line name_next osmode p2 p2_over p3 p3_over pp_cen pp_lst pp_lst_all pp_lst_over ss x_big x_sort y_big y_sort)
(setvar "mirrtext" 1)(setvar "cmdecho" 0)(setq osmode (getvar "osmode"))(setq ss (ssget))(SETQ LENG (sslength ss))(setq i -1 pp_lst_all '())(repeat leng (setq i (1+ i))
(setq name (ssname ss i))(setq pp_lst (by-get-insert-box name))(setq pp_lst_all (append pp_lst_all pp_lst)))(setq x_sort (car(car(vl-sort pp_lst_all (function(lambda(e1 e2)(< (car e1)(car e2))))))))
(setq x_big (car(car(vl-sort pp_lst_all (function(lambda(e1 e2)(> (car e1)(car e2))))))))(setq y_sort (cadr(car(vl-sort pp_lst_all (function(lambda(e1 e2)(< (cadr e1)(cadr e2))))))))
(setq y_big (cadr(car(vl-sort pp_lst_all (function(lambda(e1 e2)(> (cadr e1)(cadr e2))))))))(setq p3(list x_sort y_sort))(setq p2(list x_big y_big))(command "_.zoom" "w" p2 p3)(setq dist (distance p2 p3))
(setq pp_cen (polar p2 (angle p2 p3) (/ (distance p2 p3) 2.0)))(setq name_line (entmakex (list '(0 . "LINE")'(100 . "AcDbEntity")'(62 . 250)'(100 . "AcDbLine") (cons 10 p3) (cons 11 p2) '(210 0.0 0.0 1.0))))
(ssadd name_line ss)(setvar "osmode" 0)(command "_.mirror" ss "" pp_cen (list (+ (car pp_cen) 100) (cadr pp_cen)) "y")(command "_.wmfout" "d://bbx.wmf" ss "")(command "_.erase" ss "")
(command "_.wmfin" "d:/bbx"  '(0 0 0) "1" "1" "0")(command "_.mirror" (entlast) "" '(0 0 0) '(100 0 0) "y")(setq pp_lst_over (by-get-insert-box (entlast)))(setq p2_over (nth 1 pp_lst_over))
(setq p3_over (nth 2 pp_lst_over))(setq dist_pd (distance p2_over p3_over))(command "_.scale" (entlast) "" p2_over (/ dist dist_pd))(command "_.move" (entlast) "" p2_over p2)
(setq name_next (entlast))(command "_.explode" (entlast) "")(entdel (entlast))(command "_.zoom" "p")(setvar "mirrtext" 0)(setvar "cmdecho" 1)(setvar "osmode" osmode)(princ))
(defun by-get-insert-box(name / *bbacad* ang dist midpt objname p1 p2 p3 p4 pp_max pp_min pt1 pt2)(setq objname (vlax-ename->vla-object name))(setq *bbacad*(vlax-get-acad-object))
(vla-GetBoundingBox objname 'pp_min 'pp_max)(setq p3 (vlax-safearray->list pp_min)p2 (vlax-safearray->list pp_max)p1 (list (car p3) (cadr p2))p4 (list (car p2) (cadr p3)))(list p1 p2 p3 p4))

cheefeel

1291500406 发表于 2019-3-31 10:49
直线只能是直线，而多段线可以是直线与曲线，例如弧线的联合体。 直线的线宽是一样的，但是多段线的线宽 ...

非常感谢详细的介绍，一些超级实用的工具代码。补充一些CAD自带的系统变量：
★4 控制所绘制椭圆类型 真正椭圆 或  圆弧拟合
PELLIPSE

★5 控制多段线拟合类型 连接的多段线 或 连接的圆弧
PLINECONVERTMODE
此拟合类型远比不上ET工具的FLATTEN将样条曲线转换为连接的圆弧，自行测试体会。所以这个系统变量也没啥用！