[求助]怎样求圆弧的中点

dhy · 发表于 2009-10-30 17:39

我在学一个程序，其中要用导圆弧的中点，但不知道怎样求出来，还望高手们指点一下，谢谢

Andyhon · 发表于 2009-10-30 23:49

check here:
http://discussion.autodesk.com/forums/thread.jspa?threadID=363118&tstart=17850

dhy · 发表于 2009-10-31 09:40

这样求出来的好像是终点，不是中点

(defun midPtarc (arc / arcList radius ctrPt startPt endPt midChrd mid)
(setq arcList (entget arc)
radius (cdr (assoc 40 arcList))
ctrPt (cdr (assoc 10 arcList))
startPt (polar ctrPt (cdr (assoc 50 arcList)) radius)
endPt (polar ctrPt (cdr (assoc 51 arcList)) radius)
midChrd (mapcar '* (mapcar '+ startpt endpt) '(0.5 0.5 0.5))
mid (polar ctrPt (angle ctrPt midChrd) radius)
)
)

nameld001 · 发表于 2009-10-31 10:07

(defun c:test()
(vl-load-com)
(setq ent(car(entsel)))
(setq ent_obj(vlax-ename->vla-object ent))
(setq mid_point;|中点坐标|;(vlax-curve-getpointatdist ent_obj (/ (vlax-curve-getdistatparam ent_obj(vlax-curve-getendparam ent_obj))2)))
(command "line" mid_point (mapcar '+ mid_point '(0 10)) "");测试
(princ)
)

dhy · 发表于 2009-10-31 11:16

谢谢啦

yjtdkj · 发表于 2021-6-22 09:04

(defun tt4 ()
(setq en (car (entsel)))
(setq pt_end (vlax-curve-getEndPoint en))
(setq d_end (vlax-curve-getDistAtPoint en pt_end))
(setq pt_mid (vlax-curve-getpointatdist
en
(/ d_end 2)
)
)
)

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[基础] [求助]怎样求圆弧的中点