​

let x = 200;

let y = 200;

let extraCanvas;

​

function setup() {

  createCanvas(400, 400);

  extraCanvas = createGraphics(400, 400);

  extraCanvas.clear();

  background(0);

}

​

function draw() {

​

  //no trails

  background(0);

  x += random(-5, 5);

  y += random(-5, 5);

  //trails

  if(mouseIsPressed) {

    extraCanvas.fill(255, 150);

    extraCanvas.noStroke();

    extraCanvas.circle(mouseX, mouseY, 24);

  }

  //moving the rect drawing down here allows it to be on top of our drawing trail

  image(extraCanvas, 0, 0);

  fill(255, 0, 0);

  stroke(255);

  rectMode(CENTER);

  rect(x, y, 20, 20);

}