racket/collects/frtime/demos/push-pull-ball.ss
Greg Cooper f89d241e6b under 3m, letrec doesn't seem to work the way I want for signal structures, so
I've switched to manual set!

also, cleaned up the push-pull-ball demo

svn: r4803
2006-11-07 22:14:40 +00:00

32 lines
960 B
Scheme

(require (lib "etc.ss" "frtime")
(lib "animation.ss" "frtime"))
(define radius (new-cell 20))
(define pos1
(rec pos
(until (make-posn 200 200)
(inf-delay
(let ([brnch (posn+ pos
(posn* (normalize (posn- mouse-pos pos))
(- (posn-diff pos mouse-pos) (sub1 radius))))])
(if (> (posn-diff pos mouse-pos) radius)
brnch
pos))))))
(define pos2
(rec pos
(until (make-posn 100 100)
(inf-delay
(let ([brnch (posn+ pos
(posn* (normalize (posn- pos1 pos))
(- (posn-diff pos pos1) (add1 (* 2 radius)))))])
(if (< (posn-diff pos pos1) (* 2 radius))
brnch
pos))))))
(display-shapes
(list
(make-circle pos1 radius "blue")
(make-circle pos2 radius "gray")))