;//Problem 3
;//vector
;// constructor (make-vector x y)
;//Params - x = change in x : y= change in y
(define-struct vector (cx cy))
;//selectors:
;//vector-cx - change in x
;//vector-cy - change in y
;//pred: vector? any -> true if type is vector
;------------------------------------------------;
;//plane our "world"
;// constructor (make-plane image posn vector)
;//Params - image, the plane image posn the plane position, and vector the change the direction
(define-struct plane (image posn vector))
;//selectors:
;//plane-image - planes image
;//plane-posn - planes position
;//plane-vector - planes direction
;//Pred: plane? any - true if plane
(define (move-plane plane) (make-plane (plane-image plane)
(make-posn (+ (plane-posn-X plane) (plane-vector-cx)) (+ (plane-posn-Y plane) (plane-vector-cy))) (plane-vector plane)))
(define plane1 . )

;;Our scene to render on
(define SCENE (empty-scene 600 600) )
;;Renders Earth in relation to the sun by angle SW)
(define (render-solar SW)
               (place-image plane1 300 300 SCENE ))
;(render-solar 0)
;//Problem 6b,c,d
;;Will handle a keypress if it is left or right otherwise, does nothing
(define (handle-key SW a-key)
  (cond
    [(key=? a-key "left")  (+ .1 SW)]
    [(key=? a-key "right") (- SW .2)]
    [else SW]))
(check-expect (handle-key 0 "left") .1)
(check-expect (handle-key 0 "right") -.2)
(check-expect (handle-key 0 "up") 0)
;;Handles a tick, will increase SW by .02
(define (handle-tick SW) (+ SW .02))
(check-expect (handle-tick 0) .02)
;;Handles MouseClick - Replaces earth at angle 0
(define (handle-mouse SW x y event)
  (if (mouse=? event "button-down") (- SW SW) SW))
(check-expect (handle-mouse 230 100 100 "button-down") 0)
;;Main function - runs World simulation will all events
(define (main initial-world)
(big-bang
initial-world
(to-draw render-solar)
(on-tick move-plane)
 (on-mouse handle-mouse)
(on-key handle-key)))
;;Test
(main 0)