example11.scm

;;; redefine draw function then update display automatically

(extend gl.processing)
(use gauche.threads)

(define gen-timer-id
  (let1 i 0
    (^ () (inc! i) i)))

(define (timer$ function)
  (^ (delay-time)
    (let1 id (gen-timer-id)
      (define (function* v)
        (function v)
        (glut-timer-func delay-time function* v))
      (glut-timer-func delay-time function* id))))

(define draw-update? #f)
(define draw #f)
(define-macro (redraw . actions)
  `(begin
     (set! draw
           (draw$ (^ () ,@actions)))
     (set! draw-update? #t)))

(define update-timer
  (timer$ (^v (when draw-update?
                (format (current-error-port) "draw is update")
                (set! draw-update? #f)
                (draw)))))

(define main
  (setup$ (lambda ()
            (window 200 200 "animatin" 0 100)
            (update-timer 100))))

(define th (make-thread (cut main '())))
(thread-start! th)


;;redrawの中を書き換えてgoshに送ると、変更が反映される。
(redraw 
  (background 0.4 0.4 0.4)
  (rect 100 100 30 30))