let new_mouse_speed = 1;

let easing = 0.005;

​

let min_width = 2;

let max_width = 50;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  background(255);

}

​

function draw() {  

  let mouse_speed = dist(mouseX, mouseY, pmouseX, pmouseY);

  if (previous_mouse_speed >= mouse_speed){

    new_mouse_speed = lerp(previous_mouse_speed, mouse_speed, easing);

  } else {

      new_mouse_speed = lerp(mouse_speed, previous_mouse_speed, easing);

  }

  let stroke_size = map(new_mouse_speed, 0, max(width, height), min_width, max_width);

  strokeWeight(stroke_size);

​

  if (mouseIsPressed){

    line(mouseX, mouseY, pmouseX, pmouseY);

  }

  previous_mouse_speed = mouse_speed;

}