Thanks, metapict looks great! martin
On Mon, Sep 22, 2014 at 12:44 PM, Jens Axel Søgaard <jensa...@soegaard.net> wrote: > Hi Martin, > > As an example I implemented the standing wave animation. > > The MetaPict package is available through the package system. > Use the package manager in DrRacket to install install it. > The run the program below in DrRacket to see a standing wave. > > The documentation of the MetaPict package is here: > http://soegaard.github.io/docs/metapict/metapict.html > > Enjoy, > Jens Axel > > #lang racket > (require metapict > metapict/graph > (only-in 2htdp/universe animate) > (only-in 2htdp/image freeze)) > > (set-curve-pict-size 400 100) ; size 400 x 100 pixels > > ; red-circle : point -> pict > ; red disk with center in the point p drawn with black periphery > (define (red-circle p) > (def c (circle p 0.1)) > (draw (color "red" (fill c)) ; red, filled circle > c)) ; black outline > > > (define N 100) ; number of frames in the animation > (define (f m) > ; The function to graph at time t is cos(ωt)*sin(kx), where t is in > [0;2pi]. > ; First we convert the frame number to time: > (define t (* 2 pi (/ (remainder m N) N))) > (define ω 1) ; angular frequency > (define k 1) ; wave number > ; The actual function to graph > (λ (x) (* (cos (* ω t)) (sin (* k x))))) > > > (define (animation-frame m) > (with-window (window/aspect -0.2 (+ (* 4 pi) 0.2) ; x in [-0.1, 4pi+0.1] > -1.2) ; y in [-0.1, 1.1] > (pict->bitmap ; animate needs bitmaps > (draw > ; graph the function f from 0 to 4pi > (graph (f m) 0 (* 4 pi)) > ; five red dots at the nodes (0,0), (pi,0), ... > (for/draw ([n 5]) > (red-circle (pt (* n pi) 0))))))) > > ; animate them! > (animate animation-frame) > > > > 2014-09-22 20:49 GMT+02:00 Martin DeMello <martindeme...@gmail.com>: > > I was looking through http://en.wikipedia.org/wiki/User:LucasVB/Gallery > > (generated, according to the author, with a combination of php and > libgd), > > and wondered if anyone was doing similar stuff in racket. I'd love to see > > code samples if so. > > > > martin > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > > > > > -- > -- > Jens Axel Søgaard >
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