float vel = 0.2;

void keyPressed()
{
  if ( key == 'w' )
  {
    float len = dist(mouseX, mouseY, ship.x(), ship.y());
    float dx = (mouseX - ship.x())/len;
    float dy = (mouseY - ship.y())/len;
    ship.addVelocity(dx*vel, dy*vel);
    seq.playShipTrack();
  }
  if ( keyCode == ALT )
  {
    ship.shoot();
    seq.playBulletTrack();
  }
}

void keyReleased()
{
  seq.muteShipTrack();
}

void mousePressed()
{
  ship.shoot();
  seq.playBulletTrack();
}