; Draws Sierpinski Triangle and other fractals
; Using the Chaos Game.
; Takes one argument with is a vector of the 
; verticies of a polygon inside a unit square.
(define pi 3.141592654)

(define ChaosGame (lambda (vertexVector)
  (define drawWidth 700)
  (define drawHeight 720)
  (define scale 1)
  (define x 0)
  (define y 0)
  (define border 10)
  (define idx 0)
  (define vertexCount (vector-length vertexVector))




  ;;=================================================
  (define getX
    (lambda (idx)
      (vector-ref 
        (vector-ref vertexVector idx) 0)
    )
  ) 
  ;;=================================================


  ;;=================================================
  (define getY
    (lambda (idx)
      (vector-ref 
         (vector-ref vertexVector idx) 1)
    )
  ) 
  ;;=================================================

  (define getScreenX
    (lambda (x)
      (+ (floor (* x scale)) border)
    )
  ) 

                    
  (define getScreenY
    (lambda (y)
      (+ (floor (* y scale)) border)
    )
  ) 
      

  ;;=================================================
  (define getPen
    (lambda (idx)
      (vector-ref penVector idx)
    )
  ) 
  ;;=================================================




  ;;=================================================
  (define penVector 
    (vector 
       (instantiate pen% ("RoyalBlue" 4 'solid))
       (instantiate pen% ("DarkOrchid" 4 'solid))
       (instantiate pen% ("MediumSeaGreen" 4 'solid))
       (instantiate pen% ("Crimson" 4 'solid))
       (instantiate pen% ("OrangeRed" 4 'solid))
  ))
  (define pen-black 
    (instantiate pen% ("Black" 1 'solid))
  )

  ;;=================================================



  ;;=================================================
  (define frame (instantiate frame% 
    ("Chaos Game") 
      (width drawWidth) (height drawHeight)
    )
  )
  ;;=================================================

                    
                    
                    
  ;;=================================================                 
  (define plot
    (lambda (dc x y idx)
      (send dc set-pen (getPen idx))
      (send dc draw-point 
        (getScreenX x)
        (getScreenX y)
      )
    )
  )
  ;;=================================================


                    
                    
  ;;=================================================                  
  (define plot-ball
    (lambda (dc x y idx)
      (send dc set-pen (getPen idx))
    
      (send dc draw-ellipse 
        (- (getScreenX x) 3)
        (- (getScreenY y) 3) 7 7)
    )
  )
  ;;=================================================
                    
  
  ;;=================================================                  
  (define DrawVertexies (lambda (dc)
    (do ((i 0 (+ i 1))) ((>= i vertexCount))  
      (plot-ball dc (getX i) (getY i) i)
      (send dc set-pen pen-black)
      (let ((ii (modulo (+ i 1) vertexCount)))
        (send dc draw-line 
          (getScreenX (getX i)) 
          (getScreenY (getY i))
          (getScreenX (getX ii))
          (getScreenY (getY ii))
        )
      )
    )
  ))
                    
                    
                    
                    
                    
                    
                    
  ;;=================================================
  ;; Make the drawing area with a paint callback
  (define canvas 
    (instantiate canvas% (frame) 
      (paint-callback 
        (lambda (canvas dc) (drawEverything dc))
      )
    )
  )

                    
                    
                    
                    
  ;;=================================================
  (define (drawEverything dc) 
    (define drawSize
      (call-with-values 
        (lambda () (send canvas get-client-size))
        (lambda z z)
      )
    )
    (set! drawWidth (car drawSize))
    (set! drawHeight (car (cdr drawSize)))
     
    (send dc set-background 
      (make-object color% 255 255 255)
    )
    (send dc clear)
    (send dc set-smoothing 'smoothed)
  
    (set! scale (- (- 
       (min drawWidth drawHeight)
        border ) border)
    )
 
    (DrawVertexies dc)
  
  
    (set! x (random)) 
    (set! y (random))
  
    (do ((i 0 (+ i 1))) ((>= i 50000))  
      ;(sleep 1)
      (set! idx (inexact->exact (floor (* (random) vertexCount))))
      (set! x (/ (+ x (getX idx)) 2))
      (set! y (/ (+ y (getY idx)) 2))
      (plot dc x y idx)
      ;(plot-ball dc x y idx)
    )
  )

  
  ;; Show the frame
  (send frame show #t)  
))


;;=================================================
;;Vertices of equilateral triangle
(ChaosGame
  (vector (vector 0.0 1.0) 
          (vector 1.0 1.0)
          (vector 0.5 (- 1.0 (sin (/ pi 3.0))))
  )
)
;(ChaosGame
;  (vector (vector 0.0 0.0) 
;          (vector 1.0 1.0)
;          (vector 0.0 1.0)
;  )
;)


;;=================================================
;; Vertices of regular pentagon
;(ChaosGame
;  (vector (vector 0.5 0.951056516) 
;          (vector 0.0 0.587785252)
;          (vector 0.190983006 0.0)
;          (vector 0.809016994 0.0)
;          (vector 1.0 0.587785252)
;  )
;)