Noise.java

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package com.fs.starfarer.api.util;
 
import java.util.Arrays;
import java.util.Random;
 
public class Noise {
    public static Random random = new Random(Misc.genRandomSeed());
    
    public static float[] genNoise(int size, float spikes) {
        float [] noise = new float[size];
        Arrays.fill(noise, -1);
        //noise[size/2] = 1f;
//      noise[0] = 0f;
//      noise[size - 1] = 0f;
        noise[0] = 1f;
        noise[size - 1] = 1f;
        genNoise(noise, 0, size - 1, 1, spikes);
        normalizeNoise(noise, 0, 1);
        return noise;
    }
    
    
    public static void genNoise(float[] noise, int x1, int x2, int iter, float spikes) {
        if (x1 + 1 >= x2)
            return; // no more values to fill
 
        int midX = (x1 + x2) / 2;
 
        fill(noise, midX, x1, x2, iter, spikes);
        
        genNoise(noise, x1, midX, iter + 1, spikes);
        genNoise(noise, midX, x2, iter + 1, spikes);
    }
    
    private static void normalizeNoise(float[] noise, float min, float max) {
        float minNoise = Float.MAX_VALUE;
        float maxNoise = -Float.MAX_VALUE;
        for (int i = 0; i < noise.length; i++) {
            if (noise[i] == -1) continue;
            if (noise[i] > maxNoise) {
                maxNoise = noise[i];
            }
            if (noise[i] < minNoise) {
                minNoise = noise[i];
            }
        }
        if (minNoise >= maxNoise) return;
 
        float range = maxNoise - minNoise;
        for (int i = 0; i < noise.length; i++) {
            if (noise[i] != -1) {
                noise[i] = min + ((noise[i] - minNoise) / range * (max - min));
            } else {
                if (i > 0) {
                    noise[i] = noise[i - 1];
                } else if (i < noise.length - 1) {
                    noise[i] = noise[i + 1];
                } else {
                    noise[i] = .5f;
                }
            }
        }
    }
    
    private static void fill(float[] noise, int x, int x1, int x2, int iter, float spikes) {
        if (noise[x] == -1) {
            float avg = (noise[x1] + noise[x2]) / 2f;
            noise[x] = avg + ((float) Math.pow(spikes, (iter)) * (float) (random.nextDouble() - .5f));
        }
    }
}