let slider;

let button;

let playing = false;

let env;

​

function setup() {

  createCanvas(400, 400);

  wave = new p5.Oscillator();

  slider = createSlider(100, 1200, 440);

  wave.setType('sin');

  wave.start();

  wave.freq(440);

  wave.amp(0);

  button = createButton('play/pause');

  button.mousePressed(toggle);

  env = new p5.Env();

  env.setADSR(0.5, 0.2, 0.7, 0.5);

  // env.setRange(1.0, 0);

  // wave.amp(env);

}

​

function draw() {

  if (playing) {

    background(255, 0, 255); 

  } else {

    background(51);

  }

  // wave.freq(slider.value());

  wave.freq(400 + 40*abs(sin(frameCount/2)));

}

​

function mousePressed() {

    env.play(); 

}

​

function toggle() {

  if (!playing) {

    wave.amp(0.5, 1);

    playing = true;

  } else {

    wave.amp(0, 1);

    playing = false;

  }

}

​