Diamond square algorithm

Question

I\'m trying to write the Diamond-Square algorithm in Java to generate a random map but can\'t figure out the implementation...

Anyone with some Java code (or other l

Answer 1

For anyone looking, here is the algorithm provided by M. Jessup wrapped in a class that takes in a seed (to allow reproducing the results), a value for n to specify dimensions (dimensions are 2^n + 1), and exposes the results as a normalised array of floats. It also has the fix for the second part of the algorithm applied.

import java.util.Random;

public class DiamondSquare {

public float[][] data;
public int width;
public int height;

public DiamondSquare(long mseed, int n) {
    //size of grid to generate, note this must be a
    //value 2^n+1
    int DATA_SIZE = (1 << n) + 1;
    width = DATA_SIZE;
    height = DATA_SIZE;
    //an initial seed value for the corners of the data
    final float SEED = 1000.0f;
    data = new float[DATA_SIZE][DATA_SIZE];
    //seed the data
    data[0][0] = data[0][DATA_SIZE-1] = data[DATA_SIZE-1][0] = 
            data[DATA_SIZE-1][DATA_SIZE-1] = SEED;

    float valmin = Float.MAX_VALUE;
    float valmax = Float.MIN_VALUE;

    float h = 500.0f;//the range (-h -> +h) for the average offset
    Random r = new Random(mseed);//for the new value in range of h
    //side length is distance of a single square side
    //or distance of diagonal in diamond
    for(int sideLength = DATA_SIZE-1;
            //side length must be >= 2 so we always have
            //a new value (if its 1 we overwrite existing values
            //on the last iteration)
            sideLength >= 2;
            //each iteration we are looking at smaller squares
            //diamonds, and we decrease the variation of the offset
            sideLength /=2, h/= 2.0){
        //half the length of the side of a square
        //or distance from diamond center to one corner
        //(just to make calcs below a little clearer)
        int halfSide = sideLength/2;

        //generate the new square values
        for(int x=0;x