Here's a quick guide to get Processing working without the desire to wrap one's car around a tree due the sheer verbosity and inflexibility of a language.

A sneak:

Make sure Java's installed

[mchadw@zzz ~]$ which java
/usr/bin/java

Snag jRuby

• Download a recent copy of jRuby. Whatever the most recent binary on that page is will do the trick.
• Unpack the distribution somewhere you can remember. I'm going to go with ~/bin

 

cd ~/bin
tar -xzvf jruby-bin-1.0.0RC1.tar.gz
cd jruby
echo "5.times{|i| puts i}" | ./bin/jruby

If everything went to plan, you should see the expected output.

Grab Processing

• Download from processing.org. Each platform's going to be different, so snag the one that's right for you.
• Extract the file, and put it someplace where we'll know to find it. Let's say we'll also throw it in ~/bin -- but just like jRuby, it doesn't really matter where.

Fix ye Path

• Real quick -- you're going to want to open your ~/.bash_profile and let it know about jRuby's silly "install." Just add a line like this:

 

export PATH=$PATH:~/bin/jruby/bin

That'll just make sure we don't have to track the damn thing down every time.

Set your Classpath, fire it up.

The only real trick here is making sure processing's core.jar is in your classpath.

export CLASSPATH=$CLASSPATH:~/bin/Processing\ 0124/lib/core.jar

Now we should be able to make some simple processing applets. Here's the code for the 3D RGB cube:

#!/usr/bin/env jruby
require "java"

include_class "processing.core.PApplet"

class Sketch < PApplet

  def setup
    size 300, 300, P3D 
    no_stroke
    color_mode RGB, 1

    @xmag = 0
    @ymag = 0
    @newXmag = 0
    @newYMag = 0
  end

  def draw
    background 0.5, 0.5, 0.45

    push_matrix 

    translate(width/2, height/2, -30)

    @newXmag = mouseX/width.to_f * TWO_PI;
    @newYmag = mouseY/height.to_f * TWO_PI;

    diff = @xmag - @newXmag

    if (diff.abs >  0.01)
      @xmag -= diff/4.0
    end

    diff = @ymag - @newYmag
    if (diff.abs >  0.01) 
      @ymag -= diff/4.0
    end

    rotateX -@ymag
    rotateY -@xmag

    scale(50)
    begin_shape(QUADS)

    fill(0, 1, 1); vertex(-1,  1,  1)
    fill(1, 1, 1); vertex( 1,  1,  1)
    fill(1, 0, 1); vertex( 1, -1,  1)
    fill(0, 0, 1); vertex(-1, -1,  1)

    fill(1, 1, 1); vertex( 1,  1,  1)
    fill(1, 1, 0); vertex( 1,  1, -1)
    fill(1, 0, 0); vertex( 1, -1, -1)
    fill(1, 0, 1); vertex( 1, -1,  1)

    fill(1, 1, 0); vertex( 1,  1, -1)
    fill(0, 1, 0); vertex(-1,  1, -1)
    fill(0, 0, 0); vertex(-1, -1, -1)
    fill(1, 0, 0); vertex( 1, -1, -1)

    fill(0, 1, 0); vertex(-1,  1, -1)
    fill(0, 1, 1); vertex(-1,  1,  1)
    fill(0, 0, 1); vertex(-1, -1,  1)
    fill(0, 0, 0); vertex(-1, -1, -1)

    fill(0, 1, 0); vertex(-1,  1, -1)
    fill(1, 1, 0); vertex( 1,  1, -1)
    fill(1, 1, 1); vertex( 1,  1,  1)
    fill(0, 1, 1); vertex(-1,  1,  1)

    fill(0, 0, 0); vertex(-1, -1, -1)
    fill(1, 0, 0); vertex( 1, -1, -1)
    fill(1, 0, 1); vertex( 1, -1,  1)
    fill(0, 0, 1); vertex(-1, -1,  1)

    end_shape
    pop_matrix
  end

end

JFrame = javax.swing.JFrame
frame = JFrame.new "RGB Cube"
applet = Sketch.new
frame.content_pane.add applet
frame.default_close_operation = JFrame::EXIT_ON_CLOSE
applet.init
frame.pack
frame.visible = true

Grab it here if you can't work copy/paste

Reflect on Life's finer points

So, yeah. You'll see we had to set up the applet window by hand, but besides that, not all so bad. I didn't Rubify any of the java code, so it's all still a bit ugly still. But! It works! Now, go write yourself a wrapper library to make this garbage look clean.