; Zeichnen einer "Gardinenlinie"
; www.black-cad.de

(defun C:gardine ( / diff tt p1 p2 raff k)
 (setq diff 0.5 tt 0 p1 (list 0 0))

 (setq raff (getreal "\nAnzahl Falten:"))
 (setq k (getreal "\nFaltentiefe:"))

 (command "_pline")
 (command p1)
 (setq aa (* (- (sqrt (+ (* k k 2) 4)) 2) 0.125)) 
 (setq abbr (* (* 2 raff) pi))
 (while (< tt abbr)
	(setq x ( - tt (* aa (sin ( * 2 tt)))))
        (setq y  (* k (sin tt)) )
        (setq p2 ( list x y))
        (command p2 )
        (setq tt ( + tt diff))
        (setq p1 p2)
 )                                          ;endwhile
(command "" )
)