#lang racket
;Kirsten Gillis and Nelson Schicke
;CSC 151-02
;November 25, 2014
;Project: Part 2

(require gigls/unsafe)

;Modeled after position->color from reading: http://www.cs.grinnell.edu/~weinman/courses/CSC151/2014F/readings/geometric-art-reading.html
;;; Procedure:
;;;   position->color
;;; Parameters:
;;;   n, an integer
;;; Purpose:
;;;   Compute a color based on n.
;;; Produces:
;;;   color, an integer-encoded RGB color
;;; Preconditions:
;;;   0 <= n <= 1000
;;; Postconditions:
;;;   Different n values are likely to give different colors.
;;;   Nearby n values may give similar, but different colors.
(define n->color
  (lambda (n)
    (irgb (+ 128 (* 128 (sin (* pi n 0.0625))))
          (+ 128 (* 128 (cos (* pi n 0.0625))))
          (+ 128 (* 128 (sin (* pi (+ n (* n 2) 0.0625))))))))

;;; Procedure:
;;;   brush-select!
;;; Parameters:
;;;   turtle-list, a list of turtles
;;;   n, an integer between 0 and 1000 (inclusive)
;;; Purpose:
;;;   Select a brush based on n
;;; Produces:
;;;;  turtle-select-brush!, a side-effect procedure
;;; Preconditions:
;;;   0 <= n <= 1000
;;;   n must be an integer
;;;   turtle-list may not be empty
;;; Postconditions:
;;;   brush-select! will attribute a brush to turtle-list
;;;   turtle-list must be defined before running brush-select!

(define brush-select!
  (lambda (n)
    (cond [(< n 100)
           (context-set-brush! "Animated Confetti")]
          [(< n 200) 
           (context-set-brush! "Star Brush #3")]
          [(< n 300) 
           (context-set-brush! "waves")]
          [(< n 400)
           (context-set-brush! "2. Block 01")]
          [(< n 500)
           (context-set-brush! "Confetti")]
          [(< n 600)
           (context-set-brush! "Tulip Print")]
          [(< n 700)
           (context-set-brush! "sphere (29)")]
          [(< n 800)
           (context-set-brush! "Manju's Flower")]
          [(< n 900)
           (context-set-brush! "2. Star")]
          [(< n 1000)
          (context-set-brush! "1. Pixel")])))

;Draw-sin-with-parallel-lines! used with permission by Professor Weinman:
;http://www.cs.grinnell.edu/~weinman/courses/CSC151/2014F/readings/geometric-art-reading.html
;;; Procedure:
;;;   draw-sin-with-parallel-lines!
;;; Parameters:
;;;   image, an image
;;;   n, an integer
;;;   offset, an integer
;;;   start-col, an integer
;;;   mid-row, an integer
;;; Purpose:
;;;   Draw a sequence of parallel lines, with the height of the
;;;   parallel line dependent on the column.
;;; Produces:
;;;   [Nothing, called for the side effect.]
(define draw-sin-with-parallel-lines!
  (lambda (image n offset start-col mid-row)
    (let kernel! ([i 0]
                  [col start-col]
                  [row mid-row])
      (context-set-fgcolor! (n->color n))
      (when (< i n)
        (image-draw-line! image 
                          col row
                          col (- row (* row (sin (* i pi 0.05)))))
        (kernel! (+ i 1) (+ col offset) row)))))

;;; Procedure:
;;;   image-series
;;; Parameters:
;;;   n, an integer
;;;   width, a non-negative integer
;;;   height, a non-negative integer
;;; Purpose:
;;;   Create an image based on n that has the width and height given.
;;; Produces:
;;;   image, an image
;;; Preconditions:
;;;   [None Additional]
;;; Postconditions:
;;;   0 <= n <= 1000
;;;   width >= 0
;;;   height >= 0

(define image-series
  (lambda (n width height)
    (let ([image (image-compute
                  (lambda (col row)
                    (if (<= (+ (square (- col (mod n 50))) (square (- row (mod n 50))))
                            (square (/ n 20)))
                        (irgb (mod (round (* (/ n 75) col)) 255) 0 (mod (round (* (/ n 80) row)) 255))
                        (irgb (mod n 255) (mod (* n 5) 255) (mod (round (/ n 20)) 255))))
                  width height)])
      (image-show image)
      (context-set-fgcolor! (irgb (mod (* n 20) 255) (mod n 255) (mod (* n 70) 255)))
      (brush-select! n)
      (draw-sin-with-parallel-lines! image n (mod n 30) 0 (/ width 2)))))