I’ve had the itch this week to try out a few of Ruby’s game development libraries. I decided to start with Gosu. Gosu is a 2D game development library for the Ruby and C++ programming languages. It’s available for the Mac OS X, Windows, and Linux platforms and integrates with both the RMagick image processing library and the Chipmunk physics library.

Unfortunately the library is only available as a gem for Mac OS X and Windows. As a Linux user I’ve become accustom to compiling my own libraries, but this often means downloading and compiling dependencies, swearing, and a lot of Googling. I was lucky. Compiling Gosu only caused a few hairs to fall out.

If you’re an Ubuntu Feisty user, you’ll need to add the following line to the LargeImageData.hpp file located in the gosu-source-0.7.7/Gosulmpl/Graphics directory:

#include <boost/none.hpp>

This line adds a reference needed on line 31 of the LargeImageData class. With this addition, you can then execute the commands below from the gosu-source-0.7.7/linux directory to compile the Gosu game development library.

$ autoconf
$ ./configure
$ make

The make file provided with the source does not add the compiled gosu.so file to the Ruby lib directory. I chose to do this manually rather than edit the make file. Just issue the following command from the gosu-source-0.7.7/linux directory to add your newly compiled library.

$ sudo cp gosu.so /usr/lib/ruby/1.8/i486-linux/gosu.so

With a little elbow grease I successfully compiled the Gosu game development library on Ubuntu Feisty. I’ll dig into some tutorials next and post back with my results.

Be sure to check out Gosu’s, Getting Started on Linux, for a list of dependencies and compilation instructions.

If you’re experiencing the error message above while using the Rinda distributed computing module in your Ruby script then try defining a Domain name in your Network Settings configuration. This has worked in my experience using Rinda and Ruby on Ubuntu Feisty.

_Why of Why’s (Poignant) Guide to Ruby has announced the publication of a 52 page comic style book illustrating the ins and outs of his new windowing toolkit, Shoes. In his words, “Shoes is a very informal graphics and windowing toolkit. It’s for making regular old apps that run on Windows, Mac OS X and Linux. It’s a blend of my favorite things from the Web, some Ruby style, and a sprinkling of cross-platform widgets.”

Using the the latest Shoes revision, I’ve written some code to generate a Mandelbrot fractal. Try it out with the following command (assuming your script is located in the Shoes samples directory):

./shoes samples/mandelbrot.rb

You may want to go make a sandwich while you wait. Here is a sample of the output:

Here is the code:

# RB

require 'complex'

class Mandelbrot  
  def initialize(bailout=10, iterations=100)
    @bailout, @iterations = bailout, iterations   
  end  

  # A method for determining if a point is within
  # the Mandelbrot set.
  def in_set?(x, y)
    c = Complex(x, y)
    z = 0
    @iterations.times do |i|
      z = z**2 + c                       
      return false if z > @bailout
    end
    return true 
  end  
end

class Generator < Shoes
  url '/', :index

  def index()    
    render(250, 250, rgb(205, 102, 0))    
  end

  def render(height=250, width=250, color=rgb(255, 0, 0))
    nostroke
    fill color   

    mandelbrot = Mandelbrot.new

    # Render the fractal.
    0.upto(height) do |y|
      0.upto(width) do |x|
        scaled_x = -2 + (3 * x / width.to_f)
        scaled_y = 1 + (-2 * y / height.to_f)
        if mandelbrot.in_set?(scaled_x, scaled_y) then        
          rect :left => x, :top => y, :width => 1, :height => 1
          # oval :left => x, :top => y, :radius => 1, :center => true                           
        end      
      end
    end
  end
end

Shoes.app :title => 'Mandelbrot', :height => 250, :width => 250