(setup 1200 1000)
(bgcolor "black")
(color (rgb 1 0 0))
(speed 0)
(penup)
(hideturtle)

(define xvals1 (list 2.005 1.005 2.005 4.005 4.005 2.005))
(define xvals2 (list 4 7 2 6 0 1))
(define yvals1 (list 1.005 3.005 1.005 1.005 3.005 1.005))
(define yvals2 (list 5 1 7 1 4 5))

(define (get-xy vals1 vals2 time sum)	; finds next (x,y) coordinates
	(if (null? vals1) sum
		(get-xy (cdr vals1) (cdr vals2) time
			(+ sum (sin (+ (* time (car vals1)) (car vals2)))))))

(define (go time scale)					; moves turtle to new coordinates
	(define xy (cons (get-xy xvals1 xvals2 time 0) (get-xy yvals1 yvals2 time 0)))
	(goto (* (car xy) scale) (* (cdr xy) scale)))

(define (more-green g time scale)		; increases green component
	(cond ((>= g 1) (less-red 1 time scale))
		(else 
			(color (rgb 1 g 0))
			(go time scale)
			(more-green (+ g 0.000142) (+ time 0.02) (* scale 0.99995)))))

(define (less-red r time scale)			; decreases red component
	(cond ((<= r 0.8) 'end)
		(else 
			(color (rgb r 1 0))
			(go time scale)
			(less-red (- r 0.000142) (+ time 0.02) (* scale 0.99995)))))

(go 0 130)
(pendown)
(more-green 0.000142 0.02 129.9935)