椭园怎样转成多段线？

jiangh1969 · 发表于 2006-10-11 09:23:40

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有谁知道一段椭园弧如何转成多段线。

唐昕晨 · 发表于 2006-10-11 13:25:57

pellipse设置一下这个系统变量,看看是不是你想要的.

supernova · 发表于 2006-10-11 16:35:51

我一个笨招：
绘制好椭圆后，使用offset命令偏移一下，在按相同的偏移距离再偏移回来就可以了。

c3m3y0 · 发表于 2006-10-11 19:44:19

打断试一下，可以吗？

xiaopan83 · 发表于 2006-10-12 20:52:13

《转贴》AUTOLISP程序

;;;======================
;;;= 将椭圆转化成多义线 =
;;;======================
(defun fcp::ellipsetopline
                  (ellobj /          spoint    epoint
                  str          num1    num    plineobj
                  plineobj1 points    npoints    vpoints
                  2dpoints
                  )
(setq    spoint (list (vlax-safearray-get-element
            (setq
               num (vlax-variant-value (vla-get-startpoint ellobj))
            )
            0
            )
            (vlax-safearray-get-element num 1)
            (vlax-safearray-get-element num 2)
      )
   epoint (list (vlax-safearray-get-element
            (setq
               num (vlax-variant-value (vla-get-endpoint ellobj))
            )
            0
            )
            (vlax-safearray-get-element num 1)
            (vlax-safearray-get-element num 2)
      )
)
(setq    plineobj (car (vlax-safearray->list
               (vlax-variant-value (vla-offset ellobj -0.1))
            )
         )
)
(setq
  plineobj1 (car (vlax-safearray->list
            (vlax-variant-value (vla-offset plineobj 0.1))
            )
      )
)
(vla-delete plineobj)
(setq    points nil
   num -1
   2dpoints nil
)
(setq
  points (vlax-safearray->list
      (vlax-variant-value (vla-get-ControlPoints plineobj1))
      )
)
(vla-delete plineobj1)
(setq    npoints    nil
   num    (/ (length points) 3)
)
(repeat num
  (if    (>= (length points) 3)
(setq npoints (append
            npoints
            (list (list (car points) (cadr points) (caddr points))
            )
            )
      points (cdddr points)
)
  )
)
(setq    points    npoints
   vpoints    (list (car points))
   num    1
)
(if (> (setq str (length points)) 16)
  (progn
(setq num1 (fix (/ str 16)))
(while (< num str)
   (if (= 0 (rem num num1))
   (setq vpoints (append vpoints (list (nth (- num 1) points))))
   )
   (setq num (+ num 1))
)
(setq points (append vpoints (list (last npoints))))
  )
)
(foreach num points
  (setq points (subst    (vlax-curve-getClosestPointTo ellobj num)
               num
               points
         )
  )
)
(princ points)
(setq    points (subst spoint
            (car points)
            (subst epoint (last points) points)
      )
)
(foreach num points
  (setq 2dpoints
      (append 2dpoints num)
  )
)
(setq    vpoints    (vlax-make-safearray
         vlax-vbdouble
         (cons 0 (- (length 2dpoints) 1))
         )
)
(vlax-safearray-fill vpoints 2dpoints)
(setq plineobj (vla-addpolyline fcp::mspaceobj vpoints))
(if (and (= (car spoint) (car epoint))
      (= (cadr spoint) (cadr epoint))
)
  (vla-put-closed plineobj :vlax-true)
)
(vla-put-type plineobj acfitcurvepoly)
plineobj
)

再配上变量定义：
(vl-load-com)
(setq fcp::acadobj    (vlax-get-acad-object)
  fcp::acaddocobj    (vla-get-activedocument fcp::acadobj)
  fcp::mspaceobj    (vla-get-modelspace fcp::acaddocobj)
  fcp::pspaceobj    (vla-get-paperspace fcp::acaddocobj)
  fcp::docobj    (vla-get-documents fcp::acadobj)
  fcp::blocksobj    (vla-get-blocks fcp::acaddocobj)
  fcp::layersobj    (vla-get-layers fcp::acaddocobj)
  fcp::textstyles    (vla-get-Textstyles fcp::acaddocobj)
  fcp::linetypes    (vla-get-linetypes fcp::acaddocobj)
  fcp::menugroupsel    (vla-get-menugroups fcp::acadobj)
  fcp::menugroup    (vla-item fcp::menugroupsel 0)
  fcp::menuobj    (vla-get-menus fcp::menugroup)
)

xiaopan83 · 发表于 2006-10-12 20:54:00

如果不想这样，我想可以考虑用多线段近似画椭圆弧，在要求不高的情况下还是可以的，

wuuuuu · 发表于 2010-3-12 11:46:06

3# supernova 的办法试验了一下。可以做到把椭圆转成样条曲线。
如果要多线段的话，还有一步，就是点击样条曲线，右键，编辑，转换成多线段。
要精度的话，选项值10左右就可以，不要精度的话，选项值0即可。

还有一招，将带有椭圆的图形，另存为 R12版本，再打开的时候，你会发现椭圆变成了多线段。
这一招也是学来的。

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