racket/collects/frtime/demos/ball-on-string.ss
2008-02-23 09:42:03 +00:00

12 lines
314 B
Scheme

(require frtime/animation)
(define-values (pos vel)
(letrec ([pos (posn-integral vel)]
[vel (posn/ (posn- mouse-pos (inf-delay pos)) 400.0)])
(values pos vel)))
(display-shapes
(list
(make-line mouse-pos pos "gray")
(make-circle pos (+ 10 (/ 400 (+ 40.0 (posn-diff mouse-pos pos)))) "blue")))