前面有介绍过两种CAD画两条样条线的中心线的方法，分别是用三维曲面提取中心线和画辅助取中心线，这两种方法。其实还有更简单的方法，就是用插件，感兴趣的可以自己找有相关功能的插件来使用。

这里提供一个。

(defun c:zx( / ent1 ent2 num p1list p2list p3list i cp p1 cv1 cv2 stp endp) (setq ent1 (car (entsel "\n选择第1对象:")))

(setq ent2 (car (entsel"\n选择第2对象:")))

(setq cv1 ent1 cv2 ent2)

(setq num (getint "\n控制点数量(越多效果越好:"))

(if (ssget "x" (list (cons 0 "POINT"))) (command "erase" (ssget "x" (list (cons 0 "POINT"))) ""))

(command "divide" ent1 num)

(setq ent1 (ssget "x" (list (cons 0 "POINT"))))

(setq p1list nil i 0)

(while (setq cp (ssname ent1 i))

(setq p1list (append p1list (list (cdr (assoc 10 (entget cp))))))

(setq i (1+ i))

)

(setq stp (vlax-curve-getStartPoint cv1) endp (vlax-curve-getEndPoint cv1))

(if (> (distance stp (nth 0 p1list)) (distance endp (nth 0 p1list)))

(setq p1list (append (list endp) p1list (list stp)))

(setq p1list (append (list stp) p1list (list endp)))

)

(command "erase" ent1 "")

(command "divide" ent2 num)

(setq ent2 (ssget "x" (list (cons 0 "POINT"))))

(setq p2list nil i 0)

(while (setq cp (ssname ent2 i))

(setq p2list (append p2list (list (cdr (assoc 10 (entget cp))))))

(setq i (1+ i))

)

(setq stp (vlax-curve-getStartPoint cv2) endp (vlax-curve-getEndPoint cv2))

(if (> (distance stp (nth 0 p2list)) (distance endp (nth 0 p2list)))

(setq p2list (append (list endp) p2list (list stp)))

(setq p2list (append (list stp) p2list (list endp)))

)

(command "erase" ent2 "")

(if (> (distance (nth 0 p1list) (nth 0 p2list)) (distance (nth 0 p1list) (nth (- num 2) p2list)))

(setq p2list (reverse p2list))

)

(setq i 0 p3list nil)

(while (and (setq cp (nth i p1list)) (setq cp1 (nth i p2list)))

(setq p3 (list (* (+ (car cp) (car cp1)) 0.5) (* (+ (cadr cp) (cadr cp1)) 0.5)))

(setq p3list (append p3list (list p3)) i (1+ i))

)(command "undo" "be")

(setq temposm (getvar "osmode"))

(setvar "osmode" 0)

(setq i 2 p1 (nth 0 p3list) cp (nth 1 p3list))

(command "pline" (trans p1 0 1) (trans cp 0 1) "")

(setq ent1 (entlast) p1 cp)

(while (setq cp (nth i p3list))

(command "line" (trans p1 0 1) (trans cp 0 1) "")

(command "pedit" ent1 "J" (entlast) "" "")

(setq p1 cp i (1+ i))

)

(setvar "osmode" temposm)(command "undo" "e")

(princ)

)

这种方法相对来说更简单，能很快生成一个近似中心线来，这段代码生成的是一个多段线。

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