畫管路圖時，常畫俯視圖和相應的45°角視圖。其實45°角視圖中包含的信息只比俯視圖中多了每根管路的水平高度。下面這個用LISP編寫的程序可以自動將俯視圖轉化為同一水平高度的45°角視圖，使用者只需在轉化后的圖上將每組管路在豎直方向上移動相應的高度，一幅45°角視圖就輕鬆完成了。
由於每根管路用一直線表示，所以只需改變直線的起點和終點坐標為相應的45°角視圖中的坐標。程序中變數p0記錄45°角視圖的坐標原點，由用戶輸入。p1記錄直線的起點坐標，p2記錄直線的終點坐標。
(defun c:V45( / cmdmode sset ssl ent p0,p1,p2,x1,x2,y0,y1,y2,z1,z2)
(setq cmdmode (getvar "cmdecho"))
(setvar "cmdecho" 0)
;select lines by user
(prompt "\nSelect lines:")
(setq sset (ssget))
(if (not(null sset))
(progn
(setq ssl (sslength sset))
;input base point by user
(setq p0 (getpoint "\nThe base point: "))
(setq y0 (cadr p0))
(while (> ssl 0)
(setq ent(entget (ssname sset (setq ssl (1- ssl)))))
;filter the lines
(if (= (cdr (assoc 0 ent)) "LINE")
;change the start point and end point of the line
(progn
(setq x1 (cadr(assoc 10 ent)))
(setq y1 (caddr(assoc 10 ent)))
(setq z1 (cadddr(assoc 10 ent)))
(setq x2 (cadr(assoc 11 ent)))
(setq y2 (caddr(assoc 11 ent)))
(setq z2 (cadddr(assoc 11 ent)))
(setq p1 (list (+ x1 (/ (* (sqrt 2) (- y1 y0)) 4)) (+ y0 (/ (* (sqrt 2) (- y1 y0))4)) z1))
(setq p2 (list (+ x2 (/ (* (sqrt 2) (- y2 y0)) 4)) (+ y0 (/ (* (sqrt 2) (- y2 y0))4)) z2))
(setq ent (entmod (subst (cons 10 p1)
(assoc 10 ent) ent)))
(entmod (subst (cons 11 p2)
(assoc 11 ent) ent))
(redraw (cdr(assoc -1 ent)) 1))
)
)
)
)
(setvar "CMDECHO" cmdmode)
)
(princ "\n\tc:V45 loaded. Start command with V45.")
