game.rb

require 'rubygems'
require 'rubygame'
require './lib/shared.rb'
require './lib/pause.rb'
require './lib/about.rb'
require './lib/title.rb'
require './lib/ingame.rb'
Rubygame::TTF.setup

class Game

	attr_accessor :screen, :queue, :clcok, :state

	def initialize
		@screen = Rubygame::Screen.new [640, 480], 0, [Rubygame::HWSURFACE, Rubygame::DOUBLEBUF]
		@screen.title = "Pong"
		@queue = Rubygame::EventQueue.new
		@clock = Rubygame::Clock.new
		@clock.target_framerate = 60

		# The state has to be changed by the developer
		# using the game class, or else the game won't
		# start successfully
		@state = nil
		@state_buffer = nil
	end

	def run!
		loop do
			update
			draw
			@clock.tick
		end
	end

	def update
		@queue.peek_each do |ev|
			case ev
			when Rubygame::QuitEvent
				Rubygame.quit
				exit
			when Rubygame::KeyDownEvent
				# This is somewhat of a hack since EventQueue#push seems to
				# add on events while your still looping over the queu, meaning
				# that if we handle this in the Title state, the QuitEvent will
				# be processed before the Game class can see it
				if ev.key == Rubygame::K_ESCAPE and @state.class == Title
					@queue.push Rubygame::QuitEvent.new
				end
			end
		end
		@state.update
		if @state_buffer != nil
			@state = @state_buffer
			@state_buffer = nil
		end
	end

	def draw
		@state.draw
	end

	def switch_state state
		if @state != nil
			@state_buffer = state
		else
			@state = state
		end
	end
end

g = Game.new
g.switch_state Title.new(g)
g.run!