/// <summary>
/// Draw the game world, effects, and HUD
/// </summary>
/// <param name="gameTime">The elapsed time since last Draw</param>
public override void Draw(GameTime gameTime)
{
float elapsedTime = (float)gameTime.ElapsedGameTime.TotalSeconds;
ScreenManager.SpriteBatch.Begin();
DrawBackground(elapsedTime);
DrawAliens();
DrawPlayer();
DrawBullets();
particles.Draw();
DrawForeground(elapsedTime);
DrawHud();
ScreenManager.SpriteBatch.End();
}
