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continuing to try the boid example

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This commit is contained in:
Danny Yoo 2011-09-12 16:37:35 -04:00
parent e4c690ad1f
commit 1f5e848fa0
1 changed files with 22 additions and 23 deletions
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45
web-world/examples/boid/boid.rkt
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@ -1,5 +1,8 @@
#lang planet dyoo/whalesong #lang planet dyoo/whalesong
(require (planet dyoo/whalesong/js)
(planet dyoo/whalesong/web-world))
;; Boid flocking behavior. ;; Boid flocking behavior.
;; ;;
@ -11,6 +14,10 @@
(define-struct boid (velocity position color)) (define-struct boid (velocity position color))
(define width (viewport-width))
(define height (viewport-height))
;; A vec represents a vector in 2d space. ;; A vec represents a vector in 2d space.
(define-struct vec (x y)) (define-struct vec (x y))
@ -151,15 +158,17 @@
;; (: rule-2 (boid (Listof boid) -> vec)) ;; (: rule-2 (boid (Listof boid) -> vec))
;; Boids try to keep a small distance away from other boids. ;; Boids try to keep a small distance away from other boids.
(define (rule-2 boid boids) (define (rule-2 boid boids)
(for/fold ([the-center (make-vec 0 0)]) (foldl (lambda (neighbor the-center)
([neighbor boids]
#:when (not (eq? boid neighbor)))
(cond (cond
[(eq? boid neighbor)
the-center]
[(too-close? boid neighbor) [(too-close? boid neighbor)
(vec- the-center (vec- (boid-position neighbor) (vec- the-center (vec- (boid-position neighbor)
(boid-position boid)))] (boid-position boid)))]
[else [else
the-center]))) the-center]))
(make-vec 0 0)
boids))
;; (: too-close? (boid boid -> Boolean)) ;; (: too-close? (boid boid -> Boolean))
@ -211,7 +220,7 @@
(cond (cond
[(out-of-bounds? (boid-position boid)) [(out-of-bounds? (boid-position boid))
(vec-normalize (vec-normalize
(vec- (make-vec (random 640) (random 480)) (vec- (make-vec (random width) (random height))
(boid-position boid)))] (boid-position boid)))]
[else [else
(make-vec 0 0)])) (make-vec 0 0)]))
@ -225,8 +234,8 @@
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; (: tick ((Listof boid) -> (Listof boid))) ;; (: tick ((Listof boid) dom -> (Listof boid)))
(define (tick boids) (define (tick boids dom)
(for/list ([b boids]) (for/list ([b boids])
(let ([mass-data (collect-mass-data (boid-neighborhood b boids 40))]) (let ([mass-data (collect-mass-data (boid-neighborhood b boids 40))])
(cap-boid-velocity (cap-boid-velocity
@ -273,10 +282,10 @@
;; draw: (listof boid) -> scene ;; draw: (listof boid) -> scene
(define (draw boids) #;(define (draw boids)
(for/fold ([scene (place-image (rectangle 640 480 'solid 'black) (for/fold ([scene (place-image (rectangle width height 'solid 'black)
320 240 320 240
(empty-scene 640 480))]) (empty-scene width height))])
([b boids]) ([b boids])
(place-image (circle 3 'solid (boid-color b)) (place-image (circle 3 'solid (boid-color b))
(vec-x (boid-position b)) (vec-x (boid-position b))
@ -284,17 +293,6 @@
scene))) scene)))
(define (key boids ke)
(cond
[(key=? ke "r")
(new-population)]
[(key=? ke "down")
(slow-down-boids boids)]
[(key=? ke "up")
(speed-up-boids boids)]
[else
boids]))
;; make-random-boid: -> boid ;; make-random-boid: -> boid
;; Makes a random boid that starts near the upper left corner, ;; Makes a random boid that starts near the upper left corner,
@ -318,7 +316,8 @@
(define (visualize) (define (visualize)
(big-bang (new-population) (big-bang (new-population)
(on-tick tick) (on-tick tick)
(to-draw draw) #;(to-draw draw)
(on-key key))) ))
(visualize) (visualize)