const FOURIER = 1;

​

// Set up

let time = 0;

let path = [];

let state = -1;

let drawing = [];

​

​

//DFT

let signalX = [];

let signalY = [];

let fourierX;

let fourierY;

​

function setup() {

  frameRate(30);

  createCanvas(700, 400);

}

​

function mousePressed() {

  state = USER;

  drawing = [];

  signalX = [];

  signalY = [];

  fourierX = [];

  fourierY = [];

  time = 0;

  path = [];

}

​

function mouseReleased() {

  state = FOURIER;

  const skip = 1;

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

    signalX.push(drawing[i].x);

    signalY.push(drawing[i].y);

  }

​

  fourierX = dft(signalX);

  fourierY = dft(signalY);

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

  fourierY.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 + rotation;

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

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

    stroke(255, 100);

    noFill();

    ellipse(prevx, prevy, radius * 2);

    fill(200);

    stroke(255);

    ellipse(x, y, 1);

    line(prevx, prevy, x, y);

  }

  return createVector(x, y);

}

​

function draw() {

  background(31);

  if (state == USER) {

    let point = createVector(mouseX - width/2, mouseY - height/2);

    drawing.push(point);

    stroke(255);

    noFill();

    beginShape();

    for (let v of drawing) {

      vertex(v.x + width/2, v.y + height/2);

    }

    endShape();

  } else if (state == FOURIER) {

    vx = epicycles(width/2, 75, 0, fourierX);

    vy = epicycles(75, height/2, HALF_PI, fourierY);

    let v = createVector(vx.x, vy.y);

    // Add final point to the array

    path.unshift(v);

    // Draw the result

    line(vx.x, vx.y, path[0].x, path[0].y); 

    line(vy.x, vy.y, path[0].x, path[0].y); 

    noFill();

    beginShape();

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

      vertex(path[i].x, path[i].y);

    }

    endShape();

    // Increment Time

    const dt = TWO_PI / fourierY.length;

    time += dt;

    if (time > TWO_PI) {

      time = 0;

      path = [];

    }

    // Remove any extra points 

    //if (path.length > fourierX.length*0.9) {

    //  path.pop();

    //}

  }

}