let gravity = 0.5;

let countBalls = 5;

let controller;

​

function setup() {

  createCanvas(800, 800);

​

  //5 balls 

  for (let i = 0; i < countBalls; i++) {

    balls.push({

      x: random(width),

      y: random(0, 100),

      r: (50), // ball size

      speedY: 0, //gravity

      color: color(random(255), random(255), random(255)) 

    });

  }

  controller = { w: 200, h: 20 };  // making controller

}

​

function draw() {

  background(255);

  mouseController();

  bounceBalls();

}

​

function mouseController() {  // control controller with mouse

  controller.x = mouseX - controller.w / 2;

  controller.y = mouseY - controller.h / 2;

  fill(150);

  rect(controller.x, controller.y, controller.w, controller.h);

}

​

function bounceBalls() {

  for (let ball of balls) {  // gravity increase 

    ball.speedY += gravity;

    ball.y += ball.speedY; 

​

    // stop if ball hits the floor 

    if (ball.y + ball.r > height) {

      ball.y = height - ball.r;

      ball.speedY *= -0.8; // slow bounce

    }

​

    // controller hits ball -> bounce

    if (controllerBounce(ball)) {

      ball.speedY *= -1; //go up

      ball.y = controller.y - ball.r;

    }

    // draw ball

    fill(ball.color);

    ellipse(ball.x, ball.y, ball.r * 2);

  }

}

​

function controllerBounce(ball) {

  return ball.x + ball.r > controller.x 

      && ball.x - ball.r < controller.x + controller.w 

      && ball.y + ball.r > controller.y 

      && ball.y - ball.r < controller.y + controller.h;

}