var posY = 100

var vx = 4

var vy = 4

var radius = 50

var thick = 10

​

function setup() {

  createCanvas(400, 400)

​

}

​

function draw() {

  background(0)

  fill(255)

​

  rect(100, 100, 200, 200)

​

​

  if (mouseIsPressed == true) {

    drawWall()

  }

​

  ellipse(posX, posY, radius)

  posX = posX + vx

  posY = posY + vy

​

  if (posX > width - radius / 2 - thick) {

    vx = vx * -1

  }

​

  if (posX < radius / 2 + thick) {

    vx = vx * -1

  }

​

  if (posY > height - radius / 2 - thick) {

    vy = vy * -1

  }

​

  if (posY < radius / 2 + thick) {

    vy = vy * -1

  }

}

​

​

function drawWall() {

  rect(0, 0, width, thick)

  rect(width - thick, 0, thick, height)

  rect(0, height - thick, width, thick)

  rect(0, 0, thick, height)

}