AutoLISP实现同时绘制多条直线，没有预览效果，代码如下。
(defun c:tt ()
(setq r (getreal "\n请输入风管宽度："))
(if (= nil r)
(setq r 100)
)
(while t
(if
(= p1 nil)
(setq p1 (getpoint "\n起点："))
)
(setq p2 (getpoint p1 "\n下一点："))
(command "line" p1 p2 "")
(setq ang (angle p1 p2))
(setq p1down (polar p1 (+ ang (* 1.5 pi)) (/ r 2)))
(setq p2down (polar P2 (+ ang (* 1.5 pi)) (/ r 2)))
(setq p1up (polar p1 (+ ang (/ pi 2)) (/ r 2)))
(setq p2up (polar p2 (+ ang (/ pi 2)) (/ r 2)))
(command "line" p1 p2 "")
(command "line" p1up p2up "")
(command "line" p1down p2down "")
(setq p1 p2)
)
)
代码完。
绘制的时候没有输入管道尺寸的功能，第二次调用命令的时候p1点会调用上次命令的终点。