// Daniel Shiffman

// https://thecodingtrain.com/CodingChallenges/130.1-fourier-transform-drawing.html

// https://thecodingtrain.com/CodingChallenges/130.2-fourier-transform-drawing.html

// https://thecodingtrain.com/CodingChallenges/130.3-fourier-transform-drawing.html

// https://youtu.be/7_vKzcgpfvU

​

​

let data;

​

function preload() {

  data = loadStrings('fourier.txt');

}

​

let x = [];

let fourierX;

let time = 0;

let path = [];

​

function setup() {

  createCanvas(800, 600);

​

  const skip = 1;

  // for (let i = 0; i < data.drawing.length; i += skip) {

  //   const c = new Complex(data.drawing[i].x, data.drawing[i].y);

  //   x.push(c);

  // }

  for (let i = 0; i < data.length; i += skip) {

    const s = data[i].split(',');

    const px = parseFloat(s[0] / 2);

    const py = parseFloat(s[1] / 2);

    const c = new Complex(px, py);

    x.push(c);

  }

​

  const centroid = new Complex(0, 0);

  for (let i = 0; i < x.length; i++) {

    centroid.add(x[i]);

  }

  centroid.re /= x.length;

  centroid.im /= x.length;

​

  for (let i = 0; i < x.length; i++) {

    x[i].re -= centroid.re;

    x[i].im -= centroid.im;

​

  }

​

​

  fourierX = dft(x);

  fourierX.sort((a, b) => b.amp - a.amp);

}

​

function epicycles(x, y, rotation, fourier) {

  for (let i = 0; i < fourier.length; i++) {

    let prevx = x;

    let prevy = y;

    let freq = fourier[i].freq;

    let radius = fourier[i].amp;

    let phase = fourier[i].phase;

    x += radius * cos(freq * time + phase + rotation);

    y += radius * sin(freq * time + phase + rotation);

​

    stroke(255, 100);

    noFill();

    ellipse(prevx, prevy, radius * 2);

    stroke(255);

    line(prevx, prevy, x, y);

  }

  return createVector(x, y);

}

​

function draw() {

  background(0);

​

  let v = epicycles(width / 2, height / 2, 0, fourierX);

  path.unshift(v);

​

  beginShape();

  noFill();

  for (let i = 0; i < path.length; i++) {

    vertex(path[i].x, path[i].y);

  }

  endShape();

​

  const dt = TWO_PI / fourierX.length;

  time += dt;

​

  if (time > TWO_PI) {

    time = 0;

    path = [];

  }

}