[Chief Justice]

Есть кусочек кривой в пространстве, который идентифицируется как ellipse...
Хотелось бы переделать его во что-нибудь другое....
Лучше в полилинию... Как сделать?...
Хотябы в ручную...

[Profan]

Вручную...
Поделить кривую командой "_divide" ("поделить"), скажем, на 20 частей и обвести 3D полилинией с привязкой "_nod" ("узел").
Не делить вобще, а установить привязку "_nea" ("бли") и опять же обвести 3D-полилинией.
Сгладить, если нужно.

[Кочетков Андрей]

Если есть Тооlрас, то команда E2P.

[dermoon]

Если нет этого тулпака, может проще нарисовать заново по параметрам существующего, установив PELLIPSE=1?

[Vladdik]

Сместить часть эллипса в любую сторону. Образуется сплайн, который конвертируется в полилинию. Полученную полилинию смещаем на то же самое место.

[VVA]

1. Отсюда

Saveas R12 DXF will make both ellipes and splines into plines

2. Ellipses to polylines (требуется регистрация)

Код:

[Выделить все]

;; EllipseToPolyline
;; Returns a polyline (vla-object) which is an approximation of the ellipse (or elliptical arc)
;;
;; Argument : an ellipse (vla-object)
;; http://www.theswamp.org/index.php?topic=30892.0
(defun EllipseToPolyline (el	/     cl    norm  cen	elv   pt0   pt1	  pt2	pt3   pt4   ac0
			  ac4	a04   a02   a24	  bsc0	bsc2  bsc3  bsc4  plst	blst  spt   spa
			  fspa	srat  ept   epa	  fepa	erat  n
			 )
  (vl-load-com)
  (setq	cl   (= (ang<2pi (vla-get-StartAngle el))
		(ang<2pi (vla-get-EndAngle el)))
	norm (vlax-get el 'Normal)
	cen  (trans (vlax-get el 'Center) 0 norm)
	elv  (caddr cen)
	cen  (3dTo2dPt cen)
	pt0  (mapcar '+ (trans (vlax-get el 'MajorAxis) 0 norm) cen)
	ac0  (angle cen pt0)
	pt4  (mapcar '+ cen (trans (vlax-get el 'MinorAxis) 0 norm))
	pt2  (3dTo2dPt (trans (vlax-curve-getPointAtparam el (/ pi 4.)) 0 norm))
	ac4  (angle cen pt4)
	a04  (angle pt0 pt4)
	a02  (angle pt0 pt2)
	a24  (angle pt2 pt4)
	bsc0 (/ (ang<2pi (- a02 ac4)) 2.)
	bsc2 (/ (ang<2pi (- a04 a02)) 2.)
	bsc3 (/ (ang<2pi (- a24 a04)) 2.)
	bsc4 (/ (ang<2pi (- (+ ac0 pi) a24)) 2.)
	pt1  (inters pt0
		     (polar pt0 (+ ac0 (/ pi 2.) bsc0) 1.)
		     pt2
		     (polar pt2 (+ a02 bsc2) 1.)
		     nil
	     )
	pt3  (inters pt2
		     (polar pt2 (+ a04 bsc3) 1.)
		     pt4
		     (polar pt4 (+ a24 bsc4) 1.)
		     nil
	     )
	plst (list pt4 pt3 pt2 pt1 pt0)
	blst (mapcar '(lambda (b) (tan (/ b 2.)))
		     (list bsc4 bsc3 bsc2 bsc0)
	     )
  )
  (foreach b blst
    (setq blst (cons b blst))
  )
  (foreach b blst
    (setq blst (cons b blst))
  )
  (foreach p (cdr plst)
    (setq ang  (angle cen p)
	  plst (cons
		 (polar cen (+ ang (* 2 (- ac4 ang))) (distance cen p))
		 plst
	       )
    )
  )
  (foreach p (cdr plst)
    (setq ang  (angle cen p)
	  plst (cons
		 (polar cen (+ ang (* 2 (- ac0 ang))) (distance cen p))
		 plst
	       )
    )
  )
  (setq	pl
	 (vlax-invoke
	   (vla-get-ModelSpace (vla-get-ActiveDocument (vlax-get-acad-object)))
	   'AddLightWeightPolyline
	   (apply 'append
		  (setq	plst
			 (reverse (if cl
				    (cdr plst)
				    plst
				  )
			 )
		  )
	   )
	 )
  )
  (vlax-put pl 'Normal norm)
  (vla-put-Elevation pl elv)
  (mapcar '(lambda (i v) (vla-SetBulge pl i v))
	  '(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16)
	  blst
  )
  (if cl
    (vla-put-Closed pl :vlax-true)
    (progn
      (setq spt	 (vlax-curve-getClosestPointTo pl (vlax-get el 'Startpoint))
	    spa	 (vlax-curve-getParamAtPoint pl spt)
	    fspa (fix spa)
	    ept	 (vlax-curve-getClosestPointTo pl (vlax-get el 'Endpoint))
	    epa	 (vlax-curve-getParamAtPoint pl ept)
	    fepa (fix epa)
	    n	 0
      )
      (cond
	((equal spt (trans pt0 norm 0) 1e-9)
	 (if (= epa fepa)
	   (setq plst (sublist plst 0 (1+ fepa))
		 blst (sublist blst 0 (1+ fepa))
	   )
	   (setq erat (/ (- (vlax-curve-getDistAtParam pl epa)
			    (vlax-curve-getDistAtParam pl fepa)
			 )
			 (- (vlax-curve-getDistAtParam pl (rem (1+ fepa) 17))
			    (vlax-curve-getDistAtParam pl fepa)
			 )
		      )
		 plst (append (sublist plst 0 (1+ fepa))
			      (list (3dTo2dPt (trans ept 0 norm)))
		      )
		 blst (append (sublist blst 0 (1+ fepa))
			      (list (k*bulge (nth fepa blst) erat))
		      )
	   )
	 )
	)
	((equal ept (trans pt0 norm 0) 1e-9)
	 (if (= spa fspa)
	   (setq plst (sublist plst fspa nil)
		 blst (sublist blst fspa nil)
	   )
	   (setq srat (/ (- (vlax-curve-getDistAtParam pl (rem (1+ fspa) 17))
			    (vlax-curve-getDistAtParam pl spa)
			 )
			 (- (vlax-curve-getDistAtParam pl (rem (1+ fspa) 17))
			    (vlax-curve-getDistAtParam pl fspa)
			 )
		      )
		 plst (cons (3dTo2dPt (trans spt 0 norm))
			    (sublist plst (1+ fspa) nil)
		      )
		 blst (cons (k*bulge (nth fspa blst) srat)
			    (sublist blst (1+ fspa) nil)
		      )
	   )
	 )
	)
	(T
	 (setq srat (/ (- (vlax-curve-getDistAtParam pl (rem (1+ fspa) 17))
			  (vlax-curve-getDistAtParam pl spa)
		       )
		       (- (vlax-curve-getDistAtParam pl (rem (1+ fspa) 17))
			  (vlax-curve-getDistAtParam pl fspa)
		       )
		    )
	       erat (/ (- (vlax-curve-getDistAtParam pl epa)
			  (vlax-curve-getDistAtParam pl fepa)
		       )
		       (- (vlax-curve-getDistAtParam pl (rem (1+ fepa) 17))
			  (vlax-curve-getDistAtParam pl fepa)
		       )
		    )
	 )
	 (if (< epa spa)
	   (setq plst (append
			(if (= spa fspa)
			  (sublist plst fspa nil)
			  (cons	(3dTo2dPt (trans spt 0 norm))
				(sublist plst (1+ fspa) nil)
			  )
			)
			(cdr (sublist plst 0 (1+ fepa)))
			(if (/= epa fepa)
			  (list (3dTo2dPt (trans ept 0 norm)))
			)
		      )
		 blst (append
			(if (= spa fspa)
			  (sublist blst fspa nil)
			  (cons
			    (k*bulge (nth fspa blst) srat)
			    (sublist blst (1+ fspa) nil)
			  )
			)
			(sublist blst 0 fepa)
			(if (= epa fepa)
			  (list (nth fepa blst))
			  (list (k*bulge (nth fepa blst) erat))
			)
		      )
	   )
	   (setq plst (append
			(if (= spa fspa)
			  (sublist plst fspa (1+ (- fepa fspa)))
			  (cons	(3dTo2dPt (trans spt 0 norm))
				(sublist plst (1+ fspa) (- fepa fspa))
			  )
			)
			(list (3dTo2dPt (trans ept 0 norm)))
		      )
		 blst (append
			(if (= spa fspa)
			  (sublist blst fspa (- fepa fspa))
			  (cons
			    (k*bulge (nth fspa blst) srat)
			    (sublist blst (1+ fspa) (- fepa fspa))
			  )
			)
			(if (= epa fepa)
			  (list (nth fepa blst))
			  (list (k*bulge (nth fepa blst) erat))
			)
		      )
	   )
	 )
	)
      )
      (vlax-put pl 'Coordinates (apply 'append plst))
      (foreach b blst
	(vla-SetBulge pl n b)
	(setq n (1+ n))
      )
    )
  )
  pl
)

;; Ang<2pi
;; Returns the angle expression betweem 0 and 2*pi
(defun ang<2pi (ang)
  (if (and (<= 0 ang) (< ang (* 2 pi)))
    ang
    (ang<2pi (rem (+ ang (* 2 pi)) (* 2 pi)))
  )
)

;; 3dTo2dPt
;; Returns the 2d point (x y) of a 3d point (x y z)
(defun 3dTo2dPt (pt) (list (car pt) (cadr pt)))

;; Tan
;; Returns the angle tangent
(defun tan (a) (/ (sin a) (cos a)))

;; SUBLIST 
;; Returns a sub list
;;
;; Arguments
;; lst : a list
;; start : start index (first item = 0)
;; leng : the sub list length (number of items) or nil
(defun sublist (lst start leng / n r)
  (if (or (not leng) (< (- (length lst) start) leng))
    (setq leng (- (length lst) start))
  )
  (setq n (+ start leng))
  (while (< start n)
    (setq r (cons (nth (setq n (1- n)) lst) r))
  )
)

;; K*BULGE
;; Returns the proportinal bulge to the reference bulge
;; Arguments :
;; b : the bulge
;; k : the proportion ratio (between angles or arcs length)
(defun k*bulge (b k / a)
  (setq a (atan b))
  (/ (sin (* k a)) (cos (* k a)))
)


;; EL2PL
;; Converts ellipses and elliptcal arcs into polylines

(defun c:el2pl (/ *error* fra acdoc ss)
  (vl-load-com)
  (defun *error* (msg)
    (if (and (/= msg "Fonction annulee")
             (/= msg "Function cancelled")
        )
      (princ (strcat (if (= "FRA" (getvar 'locale))
                       "\nErreur: "
                       "\Error: "
                     )
                     msg
             )
      )
    )
    (vla-endUndoMark acdoc)
    (princ)
  )
  (setq acdoc (vla-get-ActiveDocument (vlax-get-acad-object)))
  (if (ssget '((0 . "ELLIPSE")))
    (progn
      (vla-StartUndoMark acdoc)
      (vlax-for e (setq ss (vla-get-ActiveSelectionSet acdoc))
        (EllipseToPolyline e)
        (vla-delete e)
      )
      (vla-delete ss)
      (vla-EndUndoMark acdoc)
    )
  )
  (princ)
)

;; PELL
;; Draws an ellipse or an elliptical arc approximation (polyline) on the fly
(defun c:pell (/ *error* ec pe old ent)
  (vl-load-com)
  (defun *error* (msg)
    (if (and msg
             (/= msg "Fonction annulee")
             (/= msg "Function cancelled")
        )
      (princ (strcat (if (= "FRA" (getvar 'locale))
                       "\nErreur: "
                       "\Error: "
                     )
                     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))))
    (progn
    (EllipseToPolyline (vlax-ename->vla-object ent))
    (entdel ent)
    )
  )
  (*error* nil)
)

3. ConvTo2d -Преобразование линейных объектов в 2D полилинии

[Profan]

Теперь как бы последние 2 сообщения переправить в 2006 год...