let mouseLocs = [];

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  for (let i = 0; i < LENGTH; i++) {

    mouseLocs.push(createVector(width / 2, height / 2));

  }

}

​

function draw() {

  background(0);

  mouseLocs.push(createVector(mouseX, mouseY));

  mouseLocs.shift();

  noFill();

  stroke(255);

  strokeWeight(3);

  for (let i = 0; i < LENGTH; i += 10) {

    let radius = map(i, 0, LENGTH - 1, width, 10);

    circle(mouseLocs[i].x, mouseLocs[i].y, radius);

  }

}