The Rubygame Book Part 3

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Welcome to Part 3. Here we set up the controller class, which is a class where everything comes together. In this part, however, we won't teach you anything new. What we're doing here is setting up the code necessary for further learning and eventually completing the game.

A New Class

Lucky for us, we have created the controller file in the beginning of the tutorial. So it is a matter of us filling the empty file with code.

modify lib/controller.rb:

class Controller
  def initialize screen
    @screen = screen
    @queue = Rubygame::EventQueue.new()
  end
  def run
    loop do
      @queue.each do |ev|
        case ev
        when Rubygame::QuitEvent
          Rubygame.quit()
          exit
        when Rubygame::KeyDownEvent
          case ev.key
          when Rubygame::K_ESCAPE
            Rubygame.quit()
            exit
          end
        end
      end
    end
  end
end

As you can see, it is not much different from the setup class in lib/setup.rb. However, since it is the class that pull all the game component together, you can bet that it will look vastly different than setup.rb in later stages of the tutorial.

You may have noticed that the initialize require the argument called screen. This is the same screen we used last time in setup.rb and it will be the screen that we use everywhere else in the source code.

Going Back to Setup Class

Since the Controller class is not going to initialize or execute the run method on its own, we're going back to Setup class to do these very things.

First, we got to initialize the Controller object. So modify the initialize method in Setup.

modify lib/setup.rb:

def initialize
  @screen = Screen.new([800,600],0,[Rubygame::HWSURFACE,Rubygame::DOUBLEBUF])
  @queue = Rubygame::EventQueue.new()
  @control = Controller.new(@screen)
end

Now we can use the Controller class in Setup. Now, we're going to add a conditional statement that allow us to execute the loop in Controller#run. For this task, modify the run method in Setup.

modify lib/setup.rb:

def run
  loop do
    @queue.each do |ev|
      case ev
      when Rubygame::QuitEvent
        Rubygame.quit()
        exit
      when Rubygame::KeyDownEvent
        case ev.key
        when Rubygame::K_ESCAPE
          Rubygame.quit()
          exit
        when Rubygame::K_RETURN
          @control.run()
        end
      end
    end
  end
end

The changes that you see in this method is the addition of Rubygame::K_RETURN conditional statement. Here, we chosen return as the key from which to launch the game.

Running the game

Since you currently cannot know which loop you are in, it might be advisable to add something like:

puts "This is the controller."

to the controller's run method to indicates that you have entered the run loop of Controller class.

If successful, you should see this message when you press enter during the time that the game run. Once you accomplish the task, remove the message and continue on to Part 4.