Data commit

Task/Polyspiral/Racket/polyspiral.rkt

@@ -0,0 +1,25 @@
+#lang racket
+
+(require 2htdp/universe pict racket/draw)
+
+(define ((polyspiral width height segment-length-increment n-segments) tick/s/28)
+  (define turn-angle (degrees->radians (/ tick/s/28 8)))
+  (pict->bitmap
+   (dc (λ (dc dx dy)
+         (define old-brush (send dc get-brush))
+         (define old-pen (send dc get-pen))
+         (define path (new dc-path%))
+         (define x (/ width #i2))
+         (define y (/ height #i2))
+         (send path move-to x y)
+         (for/fold ((x x) (y y) (l segment-length-increment) (a #i0))
+                   ((seg n-segments))
+           (define x′ (+ x (* l (cos a))))
+           (define y′ (+ y (* l (sin a))))
+           (send path line-to x y)
+           (values x′ y′ (+ l segment-length-increment) (+ a turn-angle)))
+         (send dc draw-path path dx dy)
+         (send* dc (set-brush old-brush) (set-pen old-pen)))
+       width height)))
+
+(animate (polyspiral 400 400 2 1000))