如何在AutoCAD中画缓和曲线
一、在CAD中画出切线长
二、运行程序： 在命令行中输入hh回车
三、选择两条切线，然后输入曲线半径如：2204.5回车
四、输入缓和曲线长，如270，绘图完成！如图
记事本格式内容，新建的lisp语言，在CAD中要先加载
;;多义线摹拟缓和曲线。
;;输入起止直线、半径、缓和曲线长或设计车速。
;;命令：HH
(defun com_p()
(setq l 0)
(command "ucs" "o" (list (- 0 x1) 0 0))
(command "pline" (list 0 0 0) "w" "0" ""
(repeat 1000
(setq l (+ l (/ Ls 1000))
x (+ (- l (/ (* l l l l l) 40 C C)) (/ (* l l l l l l l l l) 3456 C C C C))
y (* id__ (+ (- (/ (* l l l) 6 C) (/ (* l l l l l l l) 336 C C C)) (/ (* l l l l l l l l l l l) 42240 C C C C C)))
);setq
(command (list x y 0))
);repaet
);command
(setq pt5 (trans (list x y 0) 1 0))
);com_p
(defun ll_v()
(setq V (getreal "nGive Velocity:")
Ls1 (* V 0.85)
Ls2 (/ (* 0.0357 V V V) R)
Ls (max Ls1 Ls2 (/ R 9))
Ls (* (fix (/ Ls 10)) 10.0)
);setq
(if (> Ls R) (setq Ls R))
(ll_d)
);ll_v
(defun ll_d()
(setq os (getvar "osmode"))
(setvar "osmode" 0)
(setq C (* Ls R)
q (- (+ (- (/ Ls 2) (/ (* Ls Ls Ls) 240 R R)) (/ (* Ls Ls Ls Ls Ls) 34560 R R R R)) (/ (* Ls Ls Ls Ls Ls Ls Ls) 8386560 R R R R R R))
pt1 (cdr (assoc 10 (entget (car p1))))
pt2 (cdr (assoc 11 (entget (car p1))))
pt10(polar pt1 (angle pt1 pt2) (/ (distance pt1 pt2) 2))
pt3 (cdr (assoc 10 (entget (car p2))))
#p#分页标题#e# pt4 (cdr (assoc 11 (entget (car p2))))
pt20(polar pt3 (angle pt3 pt4) (/ (distance pt3 pt4) 2))
p (+ (- (/ (* Ls Ls) 24 R) (/ (* Ls Ls Ls Ls) 2688 R R R)) (/ (* Ls Ls Ls Ls Ls Ls) 506880 R R R R R))
jd (inters pt1 pt2 pt3 pt4 nil)
alf1(angle pt10 jd)
alf2(angle pt20 jd)
alf (- (angle jd pt20) alf1)
);setq
(if (or (> alf pi) (and (< alf 0) (> alf (- 0 pi))))
(progn
(setq id__ -1)
(if (> alf pi) (setq alf (- (+ pi pi) alf)) (setq alf (abs alf)))
);progn
(progn
(setq id__ 1)
(if (<= alf (- 0 pi)) (setq alf (+ pi pi alf)))
);progn
);if
(setq x0 (/ (* (+ p R) (sin(/ alf 2.0))) (cos(/ alf 2.0)))
x1 (+ x0 q)
Cl (+ (* alf R) Ls)
E (- (/ (+ R p) (cos(/ alf 2))) R)
);setq
(command "ucs" "o" jd)
(command "ucs" "z" (/ (* 180 alf1) pi))
(com_p) (setq pt6 pt5)
(setq ppt1 (list x1 0 0))
(command "ucs" "")
(command "ucs" "o" jd)
(command "ucs" "z" (/ (* 180 alf2) pi))
(setq id__ (- 0 id__)) (com_p)
(setq ppt2 (list x1 0 0))
(command "ucs" "")
(if (> (abs(distance jd pt1)) (abs(distance jd pt2)))
(setq ptt1 pt1)
(setq ptt1 pt2)
);if
(setq ptt2 (polar jd alf1 (- 0 x1)))
(thh p1 ptt1 10)
(thh p1 ptt2 11)
(if (> (abs(distance jd pt3)) (abs(distance jd pt4)))
(setq ptt3 pt3)
#p#分页标题#e# (setq ptt3 pt4)
);if
(setq ptt4 (polar jd alf2 (- 0 x1)))
(thh p2 ptt3 10)
(thh p2 ptt4 11)
(if (= id__ 1) (command "arc" pt5 "e" pt6 "r" R) (command "arc" pt6 "e" pt5 "r" R))
(setq alfd (angf alf))
(setvar "osmode" os)
(command "cmdecho" "1")
(command "text" pause pause "" (strcat "偏 角＝" alfd))
(command "cmdecho" "0")
(command "text" "" (strcat "半 径＝" (rtos R 2 2)))
(command "text" "" (strcat "切 线 长＝" (rtos x1 2 2)))
(command "text" "" (strcat "曲 线 长＝" (rtos Cl 2 2)))
(command "text" "" (strcat "外 距＝" (rtos E 2 2)))
(command "text" "" (strcat "缓和曲线长＝" (rtos Ls 2 2)))
);ll_d
(defun angf (alf)
(setq alff (angtos alf 1 4)
n 1
kk (strlen alff))
(repeat kk
(setq alfn (substr alff n 1))
(if (= alfn "d")
(setq nn n));if
(setq n (+ n 1))
);repeat
(strcat (substr alff 1 (- nn 1)) "%%" (substr alff nn))
);angf
(defun c:hh(/ p1 p2 pt1 pt2 pt3 pt4 pt5 pt6 pt10 pt20 id__ R V Ls E p3
r1 x y l x0 x1 C jd alf alf1 alf2 q p Cl Ls1 Ls2)
(command "ucs" "")
(setq p1 nil p2 nil)
(while (= p1 nil) (setq p1 (entsel "n拾取第一条直线:")))
(redraw (car p1) 3)
(while (= p2 nil) (setq p2 (entsel "n拾取第二条直线:")))
(redraw (car p2) 3)
(initget 1)
(setq R (getdist "n请输入弯道半径 R: "))
(initget 1 "Ls V")
(setq p3 (getdist "n输入缓和曲线长度(Ls)或[设计速度(V)]： "))
(if (= p3 "V") (ll_v) (progn (setq ls p3) (ll_d)))
(princ)
);eline
(defun thh(len pt h)
(setq en_data (entget (car len))
old_data (assoc h en_data)
new_data (cons h pt)
en (subst new_data old_data en_data));setq
(entmod en)
);thh
公路设计中的缓和曲线在CAD中绘制时一直是个难题。
本人有一种简单的办法可以做到。望顶。
输入导线：pline命令绘制1、2、3各点，其对应坐标如下
x1=213.7748 y1=92.1117#p#分页标题#e#
x2=313.7748 y2=92.1117
x3=399.6787 y3=143.3026
绘制通过ZH、HZ、QZ、HY和YH各点的与路线导线相切的含缓和曲线的平曲线。
通过计算，五个点的直角坐标为：
ZH：X=232.9548 Y=92.1117
HY：X=285.3608 Y=94.4667
QZ：X=311.8101 Y=99.2371
YH：X=336.9780 Y=108.6801
HZ：X=383.6319 Y=133.7401
使用真样条曲线命令绘制含缓和曲线的平曲线的基本操作步骤如下：
Command: Spline(启动真样条曲线命令)
object/<Enter first point>:232.9548,92.1117(通过ZH)
Enter point :285.3608,94.4667
Close/Fit Tolerance/<Enter point>:311.8101,99.2371<通过QZ>
Close/Fit Tolerance/<Enter point>:336.9708,108.6801<通过YH>
Close/Fit Tolerance/<Enter point>:383.6319,133.7401<通过HZ>
Close/Fit Tolerance/<Enter point>:<加如回车>（选择输入切点的模式）
Enter star tangent:232.9548,92.1117 (输入起点切点)
Enter star tangent:383.6319，133.7401 （输入终点的切点）
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以上是如何绘制缓和曲线的办法了，