Category: Programming

So, I play an RPG called Earthdawn; it’s a lot like D&D, but for real nerds.

One of the things we all do in my gaming group is write our own dice rollers; rolling actual dice is SO passé–and there’s an ongoing argument about whether or not a seeded random is more or less random than the natural flaws in dice and rolling surfaces. Java is the language in which I learned to write math, so I somewhat naturally write algorithms in Java without thinking. It’s easy enough to translate this into C# or whatever.

Ok, so, here’s the algorithm. In Earthdawn, dice rolls are predicated on the step level of the difficulty. You may have an attack roll at step 18 and a damage roll at step 22. In 3rd edition Earthdawn, that translates to rolling d12+d10+d8 to attack, and 2d12+2d6 for damage. Here’s the chart (click to embiggen):

As you can see, there’s some kind of progression here; it turns out that the algorithm is a simple infinite series. There’s a jump in the number of dice every seven steps. Hence, the algorithm has a few simple steps:

(1) Divide the step number by 7.
(2) Determine and store the floor and the modulus.
(3) Roll a number of d12s equal to (floor – 1).
(4) Roll dice equal to the corresponding modulus (the first addition of dice past the 7 threshold will be 2d6, so if the modulus is 1, 2d6 are rolled and added).

That is the step algorithm such that no lookup is now necessary; Earthdawn has exploding dice and epic
fails, however, so two things are necessary. Look at the exploding dice method; if you roll the maximum value of a die, you can roll it again. You can keep rolling that die until a value shows that is less than the maximum value, such that a d6 rolled with a result of 6 can be rerolled. On the second roll, 6 results. On the third roll, 2 results, so the total value of that die roll is 14. For epic fails, if you roll more than one die and all dice show ones, you have epically failed (similar to a fumble in D&D, and with equivalent disastrous results).

Here’s my dice roller; click to embiggen:

So, here’s the code. It’s intended to be self-contained (you can see that I use a pic of Captain Malcolm Reynolds; just drop a pic in your file structure and reference it in the code if you want a background). Obviously this is bare-bones; you can adapt it at your leisure and to whatever GUI you desire. Any suggestions are welcome; I am always debugging this (and the JavaScript I’m using to display syntax highlighting is a little cranky, so forgive any indentation issues). If you can think of a way to optimize this algorithm, let me know; I always need bragging rights over the guys 😉

package dice;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import 
javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JTextField;
import javax.swing.SpinnerModel;
import javax.swing.SpinnerNumberModel;

@SuppressWarnings("serial")
public class ImagePanel extends JPanel implements ActionListener{

	int six = 6;
	int eight = 8;
	int ten = 10;
	int twelve = 12;
	int dice = 0; //counter for total number of dice
	
	public int middle; //step value entered by me.
	public boolean fail; //whether or not an epic fail happened.
	public JFrame frame;
	public Random r;
	Image img = new ImageIcon("img/MalcolmReynolds13.jpg").getImage();
	SpinnerModel stepEntry = new SpinnerNumberModel(1, 1, 300, 1);
	SpinnerModel karmaCounter = new SpinnerNumberModel(25, 0, 25, 1);
	JSpinner stepSpinner = new JSpinner(stepEntry);
	JSpinner karmaSpinner = new JSpinner(karmaCounter);
	
	private JTextField diceResult;
	private JButton myButton;
	
private JCheckBox myCheck;
	private JLabel enterStep = new JLabel("Enter Step Here.");
	
	public static void main(String[] args) {
		ImagePanel panel = new ImagePanel(new ImageIcon("img/MalcolmReynolds13.jpg").getImage());
		JFrame frame = new JFrame("Tarah's Dice Roller Of Awesomeness");
		
			frame.getContentPane().add(panel);
		    frame.pack();
		    frame.setVisible(true);
	}

	public ImagePanel(String img) {
		this(new ImageIcon(img).getImage());
	}

	public ImagePanel(Image img){
		this.img = img;
		Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
		setPreferredSize(size);
		setMinimumSize(size);
		setMaximumSize(size);
		setSize(size);
		JPanel panel = new JPanel();
		add(panel, "Center");
		myButton = new JButton("Roll The Dice.");
		myButton.addActionListener(this);
		myButton.setBorder(BorderFactory.createLineBorder(Color.black));
		diceResult = new JTextField("Roll Result", 9);
		
diceResult.setBorder(BorderFactory.createLineBorder(Color.black));
		myCheck = new JCheckBox("Use Karma.", false);
		myCheck.setBorder(BorderFactory.createLineBorder(Color.black));
		GridLayout myGrid = new GridLayout(3, 2);
		panel.setLayout(myGrid);
		panel.setBorder(BorderFactory.createLineBorder(Color.black));
		panel.add(enterStep);
		panel.add(stepSpinner);
		panel.add(myButton);
		panel.add(diceResult);
		panel.add(myCheck);
		panel.add(karmaSpinner);
		setVisible(true);
	}

	public void paintComponent(Graphics g) {
		g.drawImage(img, 0, 0, null);
	}
	
	public void actionPerformed(ActionEvent e) {
		boolean useKarma = false;
		middle = (Integer)stepSpinner.getValue();
		System.out.println("actionPerformed() thinks the step number is: " + middle);
		if (myCheck.isSelected() == true) {
			System.out.println("Using Karma.");
			useKarma = true;
			int decrease = ((Integer)karmaCounter.getValue()) - 1;
			karmaCounter.
setValue(decrease);
		}
		String s = Integer.toString(rollTheDice(useKarma, middle, fail));
	    diceResult.setText(s);

	} 

/////////////////////////////////////////////
/////////////////MATHYNESS///////////////////
/////////////////////////////////////////////
	
	//This is the Earthdawn Exploding Dice Method.
	public int d (int die){

		int sides = die;
		int result = 0;
        int roll;
    
		do {
			r = new Random();
            roll = r.nextInt(sides) + 1;
            result = result + roll;
            System.out.println("This is a d" + sides + " roll with result: " + result);
       } while (roll == sides);

		return result;
	}
	
	public int oneToSeven (int o) {
		int result = 0;
		if (o == 1) {
			result = d(six) - 3;
			if (result < 1) {
				result = 1;
			}
		}
		if (o == 2) {
			result = d(six) - 2;
			if (result < 1) {
				result = 1;
			}
		}
		if (o == 3) {
			
result = d(six) - 1;
			if (result < 1) {
				result = 1;
			}
		}
		if (o == 4) {
			result = d(six);
		}
		if (o == 5) {
			result = d(eight);
		}
		if (o == 6) {
			result = d(ten);
		}
		if (o == 7) {
			result = d(twelve);
		}
		return result;
	}
	
	public int prefix (int p) {
		int prefixTotal = 0;

		for (int i=1; i= 8) {
			int d12s = prefix(full);
			int rest = suffix(mod);
			result = d12s + rest;
			
			if (result == full+1) {
				fail = true;
			}
		}
		return result;
	}
	
	public int rollTheDice(boolean addKarma, int stepValue, boolean epicFail) {
		boolean addK = addKarma;
		dice = 0;
		int result = 0;
		result = step(stepValue);
		epicFail = fail;
		if (addK == true) {
			int dK = d(six);
			result = result + dK;
			if (epicFail == true && dK == 1) {
				JOptionPane.showMessageDialog(frame, "Epic FAIL.");
			}
		}
		else if (addK != true && epicFail == true) {
			JOptionPane.showMessageDialog(frame, "Epic FAIL.");
		}
		return 
result;
	}
}

I’ve been working on several applications for a few years; some are ready or released into the wild. I’ve used NetBeans and Eclipse to develop one application in particular; I’ve written an Earthdawn dice roller application. Earthdawn is like Dungeons & Dragons, but for real nerds. The Earthdawn dice system is complex, including a shifting iterated seven-step algorithm for determining the dice rolled for a given action. In addition, dice explode in Earthdawn. That means that if a given die results in its maximum value (i.e. a d6 result is a 6 or a d12 result is a 12), you reroll the dice and add that to the total, continuing to reroll if the die continues to result in its maximum value and stopping when it does not. Plus, you also have the option of adding a karma die (dependent on race, like Elf or Dwarf) to any roll which permits it.

Obviously, this is a complex system, and dealing with the RNG was not the hard part. The hard part was
figuring out the algorithm by which you can calculate the dice you would roll for any given step. For example, rolling a step 10 means that you roll a d8 + d6. Rolling a step 20 means that you roll 2d12 + d10. You can find this on a chart in the 3rd Edition Earthdawn Player’s Guide, but it actually took doing a Taylor series to determine that there is an algorithm which repeats every 7 steps. This means that my app can calculate what you’d roll for a step 63 dice roll, when the book doesn’t provide a chart that high.

I’ve been fiddling with this app for a year or so, and while I’ve been developing the backend in Eclipse, I found that the frontend needed some serious help. I looked around for an IDE specifically to develop the frontend of a Java app, and NetBeans turned out to be full-featured enough to develop in much the same way that I’d dev a C# app in Visual Studio 2010. I’m an old school algorithm coder, and I don’t do as much frontend app development, as opposed to my long term work in
frontend web development. In fact, most of my experience in frontend app development is in VS from 2003 on. So, believe it or not, I was looking for an IDE experience closer to VS.

NetBeans is open source; I found that specifically for the purpose of frontend Java software development, it’s a far better IDE than Eclipse. While Eclipse works better for academic algorithm coding, NetBeans is tailor-made for someone who wants to turn out an app with a backend; in fact, I coded the backend over rather a lot of time in Eclipse to test it with multiple RNGs developed at CERN, Argonne, etc, and simply copied over the relevant classes into NetBeans to hook them up to the frontend. I’d actually recommend this as the most efficient experience if you’re trying to create a complex backend with a simple and effective frontend…especially if you have an app that needs a frontend instead of a script. NetBeans has a simple application package process as well, if you need to pack up the app and send it out. I have
Ubuntu, OpenSUSE, Windows, and Mac users in my group, and Java will execute on each of those platforms.

I’ll also shortly be posting the app so you can examine it for yourselves 😉