[求助]：偏离原线一定的距离画出线

szx025

这是一个能连续划线并在线上间隔1200的距离点上园点的程序，想请高手改进一下，偏离原线一定的距离画出线上带园点的线
(defun C:str (/ pt1 pt2 l n p0 p1)
;;保存系统变量设置
(setq old_osmode (getvar "osmode"))
(setq old_CMDECHO (getvar "CMDECHO"))
(setvar "osmode" 32)
(setvar "CMDECHO" 0)
(command "-layer" "m" "栏杆" "C" "1" "" "")
(if (setq pt1 (getpoint "\n左下角点:"))
(while (setq pt2 (getpoint pt1 "\n右下角点:"))
(setvar "osmode" 0)
(setq L (distance pt1 pt2))
(command "line" pt1 pt2 "")
(command "donut" "0" "80" pt1 "")
(command "donut" "0" "80" pt2 "")
(setvar "osmode" 32)
(setq N (/ L 1200))
(setq I 1)
(setq k (angle pt1 pt2))
(setq P0 Pt1)
(while (<= i N)
(setq P1 (polar p0 k 1200))
(progn
(command "donut" "0" "80" p1 "")
(setq P0 (polar p0 k 1200))
(setq I (+ i 1))
(setq *error* olderr)
(command "")
(setq pt1 pt2)
)
)
)
)

;;恢复系统变量设置
(setvar "osmode" old_osmode)
(setvar "CMDECHO" old_CMDECHO)
(setvar "clayer" "0")
(princ)
)

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