p2-2 ej1

(define ANCHO 600)
(define ALTO 600)
(define DELTA 12)

(define Inicio (make-posn (/ ANCHO 2) (/ ALTO 2)))
(define radiomosca 2)
(define GAMMA radiomosca)
(define mosca (circle radiomosca "solid" "black"))
(define ESTADO-FINAL (make-posn -100 -100))

(define (pantalla p) (if (end? p) (text "MOSCA ATRAPADA" 56 "Green") (place-image mosca (posn-x p) (posn-y p) (empty-scene ANCHO ALTO)) ) )
(define (dist-origen M) (sqrt (+ (* (posn-x M) (posn-x M)) (* (posn-y M) (posn-y M)))))
(define (elegir-random a b) (if (= (random 2) 0) a b))

(define (checkY y d) (if (and (>= (- y d) 0) (<= (+ y d) ALTO) ) #t #f))
(define (checkX x d) (if (and (>= (- x d) 0) (<= (+ x d) ANCHO) ) #t #f))
(define (tecla I k) (cond ((key=? k "left") (make-posn (- (posn-x I) DELTA) (posn-y I)))
                          ((key=? k "right") (make-posn (+ (posn-x I) DELTA) (posn-y I)))
                          ((key=? k "up") (make-posn (posn-x I) (- (posn-y I) DELTA)))
                          ((key=? k "down") (make-posn (posn-x I) (+ (posn-y I) DELTA)))
                          (else I)
                          ))


(define (mousehandler I x y event) (cond ((string=? event "button-down") (if (or (<= (abs (- (posn-x I) x)) GAMMA) (<= (abs (- (posn-y I) y)) GAMMA)) ESTADO-FINAL I ))
                                         (else I)
                                         ))

(define (randmov I) (if (elegir-random #t #f) I ;#t -> stay, #f -> move
                          (if (elegir-random #t #f) ;#t -> vert, #f -> horiz
                                 (if (elegir-random #t #f) ;#t -> up, #f -> down
                                        (make-posn (posn-x I) (- (posn-y I) DELTA )) (make-posn (posn-x I) (+ (posn-y I) DELTA )) )
                                     (if (elegir-random #t #f) ;#t -> left, #f -> r8
                                        (make-posn (- (posn-x I) DELTA) (posn-y I)) (make-posn (+ (posn-x I) DELTA) (posn-y I) )))))

(define (end? I) (if (= (posn-x I) -100) #t #f))

(big-bang Inicio
          (to-draw pantalla)
          (on-tick randmov)
          (on-mouse mousehandler)
          (on-key tecla)
          (stop-when end?)
          )