let velocity= 1.7;

let offset = 0; 

let offset2 =0 ;

let w = 0;

let h = 0; 

​

function setup() {

  createCanvas(600, 600);

  background(220, 220,220);

}

​

function draw() {

  fill(0);

  offset = velocity + offset;

  offset2 = velocity2 + offset2;

  background(220, 220,220,30);

  w = 0 + offset;

  h = 0 + offset2;

  ellipse(w, h, 50);

  var constx = constrain(mouseX,0, width);

  var consty = constrain(mouseY,0, width);

  rect(constx,0, 100, 20);

  rect(0,constrain(mouseY,0, width), 20, 100);

  rect(constx,width-20, 100, 20);

  rect(height-20,constrain(mouseY,0, width), 20, 100);

  if(((h >= consty)&&(h <= consty + 100))&&((w > width - 20)&&(w <= width + 20))){

    velocity = -velocity;

  }

  if(((w >= constx)&&(w <= constx + 100))&&((h > height - 20)&&(h <= height + 20))){

    velocity2 = -velocity2;

  }

  if(((h >= consty)&&(h <= consty + 100))&&((w > - 20)&&(w < +20))){

    velocity = -velocity;

  }

  if(((w >= constx)&&(w <= constx + 100))&&((h > - 20)&&(h < +20))){

    velocity2 = -velocity2;

  }

}