;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;                                                        ;;;;
;;;; Copyright (c) Jun. 1996 by Takehiko Nagakura.          ;;;;
;;;; All rights reserved.                                   ;;;;
;;;;                                                        ;;;;
;;;; Do not copy, use, modify or distribute this software   ;;;;
;;;; without written permission by Nagakura. Nagakura will  ;;;;
;;;; not be responsible for any consequence of its use.     ;;;;
;;;;                                                        ;;;;
;;;; Takehiko Nagakura  (e-mail: takehiko@mit.edu)          ;;;;
;;;;    Massachusetts Institute of Technology               ;;;;
;;;;    77 Massachusetts Ave. 10-472M, Cambridge, MA 02139  ;;;;
;;;;                                                        ;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;; Last updated Feb 2, 2001 by TN 
;;;; 

; This file is an add-on to function01.lsp. Thus,
; you need to load function01.lsp before running this program.
; 
; It animates the stool by simple draw-erase loop.
;
; Use of functions
;
; (c:demoani)


; this function converts degree to radian, scale it, and compute sine wave.
(defun dsin (deg speed max) (* max (sin (* (/ deg 180.0) pi speed))))

; this function simply holts the process for given seconds. It uses
; AutoCAD system variable "date" which is represented in fractional Julian Date
(defun wait (sec / day start_time)
    (setq day (/ sec 60.0 60.0 24.0)) ; convert the sec to day
    (setq start_time (getvar "date"))
    (while (< (- (getvar "date") start_time) day)
    ) ; while
)

(defun c:demoani(/ count holt)
  (setq halt 0.06) 
  (command "ucs" "w")
  (command "ucsicon" "off")
  (command "cmdecho" 0)
  (command "zoom" (list -500 -500) (list 500 500))

  ;1) rotate the stool once 
  (setq count 0)
  (while (< count 40) 
    (command "erase" "all" "")
    (stool 0 0 (* 9 count) 60 100 35 25) 
    (setq count (+ count 1))
    (wait halt) 
   ) ; while

  ;2) bounce the stool
   (setq count 0)
   (while (< count 90)
    (command "erase" "all" "")
    (stool (dsin count 4 400) (dsin count 8 400) 0 60 100 35 25) 
    (setq count (+ count 1))
    (wait halt) 
   ) ; while

  ;3) stretch width
   (setq count 0)
   (while (< count 90)
    (command "erase" "all" "")
    (stool 0 0 0  (+ 360 (dsin (- count 22.5) 4 300)) 100 35 25) 
    (setq count (+ count 1))
    (wait halt) 
   ) ; while
  
  ;4) stretch hight
   (setq count 0)
   (while (< count 90)
    (command "erase" "all" "")
    (stool 0
         (+ 150 (dsin (- count 22.5) 4 150)) 0  60 
         (+ 400 (dsin (- count 22.5) 4 300)) 35 25) 
    (setq count (+ count 1))
    (wait halt) 
   ) ; while

  ;5) do yahoo 
   (setq count 0)
   (while (< count 90)
     (command "erase" "all" "")
     (stool 0                           ;xpos 
            0                           ;ypos
            0                           ;rotation 
            60                          ;width
            100                         ;hight
            35                          ;tank_hight
           (+ 25 (dsin (- count) 4 24)))  ;seat_radius
     (setq count (+ count 1))
     (wait halt)
  ) ; while
)

;(c:demoani)


; When this file is loaded, I will print its usage for the users.
(prompt "(c:demoani)")

; Below prevents "nil" to be printed at then end of loading.
(princ)