;;; Scheme Recursive Art Contest Entry
;;;
;;; Please do not include your name or personal info in this file.
;;;
;;; Title: <Your title here>
;;;
;;; Description:
;;;   <It's your masterpiece.
;;;    Use these three lines to describe
;;;    its inner meaning.>

; draw an isosceles triangle with height HEIGHT and base length BASE
(define (isosceles height base)
(define hyp (sqrt (+ (expt height 2) (expt (/ base 2) 2))))
(define angle (degrees (asin (/ height hyp))))
(right (+ 90 angle))
(forward hyp)
(right (- 180 angle))
(forward base)
(right (- 180 angle))
(forward hyp)
(left (- 90 angle))
)

(define (bird size fill-color)
  (define (scale factor) (* size factor))
  (pendown)
  (color fill-color)
  (begin_fill)

  ; tail
  (isosceles (scale 0.5) (scale 0.33))

  (right 180)
  (forward (scale 0.25))

  ; body
  (isosceles size (scale 0.33))

  (end_fill)
  (begin_fill)

  ; left wing
  (right 145)
  (penup)
  (forward (scale 1.1))
  (pendown)
  (isosceles (scale 0.25) (scale 1.25))
  (penup)
  (backward (scale 1.1))

  ; right wing
  (right 70)
  (forward (scale 1.1))
  (pendown)
  (isosceles (scale 0.25) (scale 1.25))
  (penup)
  (backward (scale 1.1))
  (pendown)
  (left 35)

  (forward size)
  (forward (scale 0.25))

  ; head
  (isosceles (scale 0.25) (scale .33))

  ; beak
  (forward (scale 0.0825))
  (isosceles (scale 0.165) (scale 0.0825))

  (end_fill)
  (penup)
)

(define (flock num-birds size bird-colors)
  (cond
      ((not (= 0 num-birds))
        (bird size (car bird-colors))
        (right 45)
        (forward (* 1.8 size))
        (flock (- num-birds 1) (* .8 size) (cdr bird-colors))
      )
  )
)

(define (sun num-rays radius sky-colors)
  (cond
      ((not (= 0 num-rays))
        (sun-ray radius (car sky-colors))
        (sun (- num-rays 1) (quotient radius 1.2) (cdr sky-colors))
      )
  )
)

(define (sun-ray radius fill-color)
  (setpos (+ radius 100) 100)
  (pendown)
  (color fill-color)
  (begin_fill)
  (circle radius)
  (end_fill)
  (penup)
  (setpos 100 100)
)

(define sky-colors (list "#14c0ff" "#29c5ff" "#3dcbff" "#52d0ff" "#66d6ff"
"#7bdbff" "#90e0ff" "#a4e6ff" "#b9ebff" "#cdf1ff" "#e2f6ff" "#f7fcff"))

(define bird-colors (list "#141414" "#282828" "#3c3c3c" "#505050" "#646464"
"#787878""#8c8c8c" "#a0a0a0" "#b4b4b4" "#c8c8c8" "#dcdcdc" "#f0f0f0"))

(define (draw)
  (speed 0)
  (bgcolor "#00bbff")
  (sun 12 400 sky-colors)
  (penup)
  (setpos -150 -180)
  (setheading 325)
  (flock 12 100 bird-colors)
  (hideturtle)
  (exitonclick))

; Please leave this last line alone.  You may add additional procedures above
; this line.
(draw)