let velocity;

​

let widthFormat;

let heightFormat;

​

const ballSize = 50;

const ballRadius = ballSize / 2;

​

function setup() {

  widthFormat = windowWidth;

  heightFormat = windowHeight;

​

  position = createVector(100, 100);

  velocity = createVector(3, 3);

​

  createCanvas(widthFormat, heightFormat);

  background(255);

}

​

function draw() {

  background(255);

​

  position.add(velocity);

​

  if (position.x + ballRadius > width || position.x - ballRadius < 0) {

    velocity.x *= -1;

  }

​

  if (position.y + ballRadius > height || position.y - ballRadius < 0) {

    velocity.y *= -1;

  }

​

  stroke(0);

  fill(120);

  circle(position.x, position.y, ballSize);

}

​