text: export const FPS = 30; // frames per sec
  export const FRICTION = 1; // friction coefficient of space (0 = no friction, 1 = lots of friction)
  export const LASER_DIST = 0.4; // maximum distance laser can travel as fraction of screen width
  export const LASER_MAX = 10; // maximum number of lasers on screen at once
  export const LASER_SPD = 500; // speed of lasers in pixels per sec
  export const LASER_EXPLODE_DUR = 0.1; // duration of the laser's explosion in sec
  export const ROIDS_JAG = 0; // jaggedness of the asteroids (0 = none, 1 = lots)
  export const ROIDS_NUM = 1; // number of roids
  export const ROIDS_PTS_LG = 20; // points scored for a large asteroid
  export const ROIDS_PTS_MD = 50; // points scored for a large asteroid
  export const ROIDS_PTS_SM = 100; // points scored for a large asteroid
  export const ROIDS_SIZE = 100; // starting size of asteroids in pixels per sec
  export const SHIP_BLINK_DUR = 0.1; // duration of the ship's blink during invisibility in sec
  export const SHIP_EXPLODE_DUR = 0.3; // duration of the ship's explosion
  export const SHIP_INV_DUR = 3; // duration of the ship's invisibility in sec
  export const ROIDS_SPD = 4; // max starting speed of asteroids in pixels per sec
  export const ROIDS_VERT = 50; // average number of vertices on each asteroid
  export const SHIP_SIZE = 30; // ship height in pixels
  export const SHIP_THRUST = 5; // accelerate of the ship in pixels per sec 
  export const TURN_SPEED = 180; // turn speed in degrees per sec
  export const SHOW_CENTRE_DOT = false; // show or hide ship's centre dot
  export const SHOW_BOUNDING = false; // show or hide collision bounding
  export const TEXT_FADE_TIME = 2.5; // text fade time in sec
  export const TEXT_SIZE = 40; // text font height in pixels
  export const HIT_DAMAGE = 100; // damage when hit by an asteroid
  