RidgedMulti.java

package net.tropicraft.world.perlin.generator;

import java.util.Random;

import net.tropicraft.world.perlin.FishyNoise;
import net.tropicraft.world.perlin.NoiseModule;

public class RidgedMulti extends NoiseModule {

	private final FishyNoise noiseGen;
	private final double offsetX;
	private final double offsetY;
	private final double offsetZ;
	private final int numOctaves;
	private final double[] spectralWeights = new double[32];

	public RidgedMulti(long seed, int nOctaves)
	{
		this.numOctaves = nOctaves;
		final Random rand = new Random(seed);
		this.offsetX = rand.nextDouble() / 2 + 0.01D;
		this.offsetY = rand.nextDouble() / 2 + 0.01D;
		this.offsetZ = rand.nextDouble() / 2 + 0.01D;
		this.noiseGen = new FishyNoise(seed);
		final double h = 1.0;
		for (int i = 0; i < 32; i++)
		{
			this.spectralWeights[i] = Math.pow(this.frequency, -h);
			this.frequency *= 2;
		}
		this.frequency = 1.0;
	}

	@Override
	public double getNoise(double i)
	{
		return this.getNoise(i, 0.0D);
	}

	@Override
	public double getNoise(double i, double j)
	{
		i *= this.frequency;
		j *= this.frequency;
		double val = 0;
		double weight = 1.0;
		final double offset = 1.0;
		final double gain = 2.0;
		for(int n = 0; n < this.numOctaves; n++)
		{
			double noise = this.absolute(this.noiseGen.noise2d(i + this.offsetX, j + this.offsetY));
			noise = offset - noise;
			noise *= noise;
			noise *= weight;

			weight = noise * gain;

			if(weight > 1D)
			{
				weight = 1D;
			}

			if(weight < 0D)
			{
				weight = 0D;
			}

			val += noise * this.spectralWeights[n];

			i *= 2;
			j *= 2;
		}
		return val;
	}

	@Override
	public double getNoise(double i, double j, double k)
	{
		i *= this.frequency;
		j *= this.frequency;
		k *= this.frequency;
		double val = 0;
		double weight = 1.0;
		final double offset = 1.0;
		final double gain = 2.0;
		for(int n = 0; n < this.numOctaves; n++)
		{
			double noise = this.absolute(this.noiseGen.noise3d(i + this.offsetX, j + this.offsetY, k + this.offsetZ));
			noise = offset - noise;
			noise *= noise;
			noise *= weight;

			weight = noise * gain;

			if(weight > 1D)
			{
				weight = 1D;
			}

			if(weight < 0D)
			{
				weight = 0D;
			}

			val += noise * this.spectralWeights[n];

			i *= 2;
			j *= 2;
			k *= 2;
		}
		return val;
	}

	private double absolute(double d)
	{
		if(d < 0)
		{
			d = -d;
		}
		return d;
	}

}