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;;

;; LOOP D LOOP

;;

;; Draws a red square and a blue square

;; constantly rotating (around different origins)

;; and resizing as they move away from their 

;; original point of origin.

;;

;; NOTE: Maximize the graphics display for full effect

;;

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(define canvas (gfx:make-canvas 600 600))

(define *go* #t)

;; The loop function draws, scales

;; and then rotates the path incrementing

;; the x,y origin of the rotation for the next

;; callback and also incrementing the scaleing

;; value for the next callback.

(define loopdloop

   (lambda (time path stroke fill x y scale)

      (gfx:draw-path time canvas path stroke fill)

      (gfx:scale-path time path scale scale *gfx:matrix-scale*)

      (gfx:rotate-path time path 2 x y *degrees*)

      (if *go*

          (callback (+ time 1000) 'loopdloop 

                    (+ time 3000) path stroke fill 

                    (+ x .15) (+ y .15) (+ scale 0.00001)))))

;; simple stop function.

;; make sure you call this when you've had enough

;; otherwise loopdloop will run forever.

(define stop

   (lambda ()

      (set! *go* #f)))

;; Create a red square to rotate around an origin

;; of 50,50.  Create a blue square to rotate around

;; an origin of 0,0

(define start

   (lambda (time)

      (set! *go* #t)

      (loopdloop time (gfx:make-square 50 50 50) 

                 (list 1 1 0.5 0.25) 

                 (list .9 0 0.7 0.01)

                 50 50 1.0)

      (loopdloop (+ time (* *second* 20))

                 (gfx:make-square 50 50 50)

                 (list 1 1 0.5 0.25) 

                 (list 0.1 0 1 0.025)

                 0 0 1.0)))

(stop)

(start (now))