Code snippet 19 - For multiplayer space invaders article

server.js

function startShipAndBullets() {
  gameOn = true;

  world = new p2.World({
    gravity: [0, -9.82],
  });
  shipBody = new p2.Body({
    position: [shipX, shipY],
    velocity: [calcRandomVelocity(), 0],
  });
  world.addBody(shipBody);
  startMovingPhysicsWorld();

  for (let playerId in players) {
    startDownwardMovement(playerId);
  }
}