let y;

let drop = false;

​

function setup() {

  createCanvas(400, 400);

​

  slide = createSlider(15, width - 15, 0)

  y = height / 2

}

​

function draw() {

  background(0);

  circle(slide.value(), y, 30)

​

  slide.changed(d)

​

​

  if (drop == true) {

    y = y + 2

    y = constrain(y, 0, height - 15)

​

​

​

  } else {

​

    y = height / 2

​

  }

​

​

}

​

function d() {

  drop = true

}