Initial data commit

Task/Draw-a-rotating-cube/Racket/draw-a-rotating-cube.rkt

@@ -0,0 +1,70 @@
+#lang racket/gui
+(require math/matrix math/array)
+
+(define (Rx θ)
+  (matrix [[1.0    0.0        0.0]
+           [0.0 (cos θ) (- (sin θ))]
+           [0.0 (sin θ)    (cos θ)]]))
+
+(define (Ry θ)
+  (matrix [[   (cos θ)  0.0 (sin θ)]
+           [      0.0   1.0    0.0 ]
+           [(- (sin θ)) 0.0 (cos θ)]]))
+
+(define (Rz θ)
+  (matrix [[(cos θ) (- (sin θ)) 0.0]
+           [(sin θ)    (cos θ)  0.0]
+           [   0.0        0.0   1.0]]))
+
+(define base-matrix
+  (matrix* (identity-matrix 3 100.0)
+           (Rx (- (/ pi 2) (atan (sqrt 2))))
+           (Rz (/ pi 4.0))))
+
+(define (current-matrix)
+  (matrix* (Ry (/ (current-inexact-milliseconds) 1000.))
+           base-matrix))
+
+(define corners
+  (for*/list ([x '(-1.0 1.0)]
+              [y '(-1.0 1.0)]
+              [z '(-1.0 1.0)])
+    (matrix [[x] [y] [z]])))
+
+(define lines
+  '((0 1) (0 2) (0 4) (1 3) (1 5)
+    (2 3) (2 6) (3 7) (4 5) (4 6)
+    (5 7) (6 7)))
+
+(define ox 200.)
+(define oy 200.)
+
+(define (draw-line dc a b)
+  (send dc draw-line
+        (+ ox (array-ref a #(0 0)))
+        (+ oy (array-ref a #(1 0)))
+        (+ ox (array-ref b #(0 0)))
+        (+ oy (array-ref b #(1 0)))))
+
+(define (draw-cube c dc)
+  (define-values (w h) (send dc get-size))
+  (set! ox (/ w 2))
+  (set! oy (/ h 2))
+  (define cs (for/vector ([c (in-list corners)])
+               (matrix* (current-matrix) c)))
+  (for ([l (in-list lines)])
+    (match-define (list i j) l)
+    (draw-line dc (vector-ref cs i) (vector-ref cs j))))
+
+(define f (new frame%  [label "cube"]))
+(define c (new canvas% [parent f] [min-width 400] [min-height 400] [paint-callback draw-cube]))
+(send f show #t)
+
+(send* (send c get-dc)
+  (set-pen "black" 1 'solid)
+  (set-smoothing 'smoothed))
+
+(define (refresh)
+  (send c refresh))
+
+(define t (new timer% [notify-callback refresh] [interval 35] [just-once? #f]))