Dot.js

update() {
    let vel = Vector.sub(this.pos, this.oldpos);
    vel.mult(this.friction);
    
    // if the point touches the ground set groundFriction
    if (this.pos.y >= CANVAS_HEIGHT - this.radius && vel.magSq() > 0.000001) {
      var m = vel.mag();
      vel.x /= m;
      vel.y /= m;
      vel.mult(m * this.groundFriction);
    }
    this.oldpos.setXY(this.pos.x, this.pos.y);
    this.pos.add(vel);
    this.pos.add(this.gravity);
  }