【K:CalcPlineBulge】计算多段线上目标点两侧的新凸度
本帖最后由 kucha007 于 2023-12-6 12:27 编辑主要用于打断圆弧时，保持弧度不变。
该函数已用在此程序中：http://bbs.mjtd.com/thread-189001-1-1.html
关于凸度的资料：
https://www.cnblogs.com/JJBox/articles/15863558.html
http://www.lee-mac.com/bulgeconversion.html
http://bbs.mjtd.com/thread-183667-1-1.html
;计算多段线中某一段线上目标点两侧的新凸度
;Obj Vla对象
;TgtNum多段线上目标点的参数,必须大于0
(defun K:CalcPlineBulge (Obj TgtNum / IsNeg Rad Len1 Len2 BLG1 BLG2)
(if
(and
(eq (type Obj) 'VLA-OBJECT)
(> TgtNum 0);大于0
(>= TgtNum (setq StaNum (fix TgtNum)) )
(vlax-method-applicable-p obj 'getbulge)
(setq TgtBG (vla-getbulge obj StaNum))
)
(cond
((= StaNum TgtNum);多段线顶点
(list
(vla-getbulge obj (1- StaNum))
(vla-getbulge obj StaNum)
)
)
((= TgtBG 0.0);直线段
(list 0.0 0.0)
)
((/= TgtBG 0.0);弧线段
(setq IsNeg (if (minusp TgtBG) -1 1))
(setq Rad (distance '(0.0 0.0 0.0) (vlax-curve-getsecondderiv Obj StaNum)));圆弧半径
(setq Len1 (*
0.5
(distance
(vlax-curve-getpointatparam Obj StaNum)
(vlax-curve-getpointatparam Obj TgtNum)
)
)
Len2 (*
0.5
(distance
(vlax-curve-getpointatparam Obj TgtNum)
(vlax-curve-getpointatparam Obj (+ 1.0 StaNum))
)
)
);1/2弦长
(setq BLG1 (/ (- Rad (sqrt (- (expt Rad 2) (expt Len1 2)))) Len1)
BLG2 (/ (- Rad (sqrt (- (expt Rad 2) (expt Len2 2)))) Len2)
);拱高除以1/2弦长=凸度
(list (* IsNeg BLG1) (* IsNeg BLG2))
)
)
)
)
用法示意：
(K:CalcPlineBulge (Vlax-Ename->Vla-Object (Car(Entsel))) 0.5)
感谢大佬分享源码
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