let fft;

let button;

​

let cr = 0;

let cg = 0;

let rate = 0.5;

​

function preload() {

  song = loadSound("final+drum.mp3");

}

​

function toggleSong() {

  if (song.isPlaying()) {

    song.pause();

  } else {

    song.play();

  }

}

​

function setup() {

  createCanvas(640, 640);

  angleMode(DEGREES);

  button = createButton("toggle");

  button.mousePressed(toggleSong);

  song.play();

  fft = new p5.FFT(0.9, 512);

}

​

function draw() {

  background(255);

  noStroke();

  for (let d = 0; d < width; d += 70) {

    fill(cr, cg, d, 10);

    circle(width / 2, height / 2, d);

  }

  cr += rate;

  if (cr < 0 || cr > 255) {

    rate *= -1;

  }

  cg += rate;

  if (cg < 0 || cg > 255) {

    rate *= -1;

  }

  translate(width / 2, height / 2);

  let spectrum = fft.analyze();

  for (let i = 0; i < 100; i++) {

    let angle = map(i, 0, 100, 0, 360);

    let amp = spectrum[i];

    let r = map(amp, 0, 256, 280, 150);

    let x = r * cos(angle);

    let y = r * sin(angle);

    stroke(30, 30, 120);

    strokeWeight(0.4);

    line(0, 0, x, y);

  }

}