121 lines
2.5 KiB
HTML
Executable File
121 lines
2.5 KiB
HTML
Executable File
<!doctype html>
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<html>
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<head>
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<meta charset="UTF-8" />
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<title>Fourier Series — Epicycles (p5.js)</title>
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<meta name="viewport" content="width=device-width, initial-scale=1" />
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<script src="https://cdn.jsdelivr.net/npm/p5@1.4.0/lib/p5.min.js"></script>
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<style>
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body {
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font-family: Arial, sans-serif;
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background: #fafafa;
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margin: 20px;
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text-align: center;
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}
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#container {
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max-width: 900px;
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margin: 0 auto;
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}
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h1,
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h2,
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p {
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margin: 10px 0;
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}
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input[type='range'] {
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display: block;
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margin: 10px auto 0;
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width: 260px;
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}
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</style>
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</head>
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<body>
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<div id="container">
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<h1>Fourier Series</h1>
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<p>
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This interactive sketch visualizes a Fourier series using epicycles.
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Each circle represents an odd harmonic; as you add more epicycles with
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the slider, the path on the right converges toward a square wave. The
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rotating vectors sum to a point whose vertical position is traced over
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time.
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</p>
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<div class="canvas-holder"></div>
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</div>
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<script>
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class dot {
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constructor(x, y) {
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this.x = x;
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this.y = y;
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}
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}
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class circle {
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constructor(cx, cy, r, a) {
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this.cx = cx;
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this.cy = cy;
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this.r = r;
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this.a = a;
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}
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}
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let time = 0;
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let wave = [];
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let slider;
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function setup() {
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createCanvas(900, 800);
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slider = createSlider(1, 50, 5);
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}
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function draw() {
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background(41);
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translate(250, height / 2);
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let x = 0;
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let y = 0;
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for (let i = 0; i < slider.value(); i++) {
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let prevx = x;
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let prevy = y;
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let n = i * 2 + 1;
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let radius = 100 * (4 / (n * PI));
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x += radius * cos(n * time);
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y += radius * sin(n * time);
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stroke(255, 100);
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noFill();
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ellipse(prevx, prevy, radius * 2);
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//fill(255);
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stroke(255);
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line(prevx, prevy, x, y);
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//ellipse(x, y, 8);
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}
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wave.unshift(y);
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translate(200, 0);
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line(x - 200, y, 0, wave[0]);
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beginShape();
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noFill();
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for (let i = 0; i < wave.length; i++) {
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vertex(i, wave[i]);
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}
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endShape();
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time += 0.02;
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if (wave.length > 450) {
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wave.pop();
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}
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}
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</script>
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</body>
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</html>
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