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| 1 | +package src.main.java.com.generation; |
| 2 | + |
| 3 | +import java.util.Random; |
| 4 | + |
| 5 | +/** |
| 6 | + * Implementation of the simplex noise algorithm. |
| 7 | + * @see <a href="https://en.wikipedia.org/wiki/Simplex_noise">Wikipedia</a> |
| 8 | + */ |
| 9 | +public class SimplexNoise { |
| 10 | + |
| 11 | + private SimplexNoiseOctave[] octaves; |
| 12 | + private double[] frequencys; |
| 13 | + private double[] amplitudes; |
| 14 | + private int largestFeature; |
| 15 | + private double persistance; |
| 16 | + private long seed; |
| 17 | + |
| 18 | + /** |
| 19 | + * @param largestFeature size of the largest possible feature |
| 20 | + * @param persistence the persistence |
| 21 | + * @param seed the seed |
| 22 | + */ |
| 23 | + public SimplexNoise(int largestFeature, double persistence, long seed) { |
| 24 | + |
| 25 | + this.largestFeature = largestFeature; |
| 26 | + this.persistance = persistence; |
| 27 | + this.seed = seed; |
| 28 | + |
| 29 | + int octaveCount = (int)Math.ceil(Math.log10(largestFeature) / Math.log10(2.0D)); |
| 30 | + this.octaves = new SimplexNoiseOctave[octaveCount]; |
| 31 | + this.frequencys = new double[octaveCount]; |
| 32 | + this.amplitudes = new double[octaveCount]; |
| 33 | + |
| 34 | + Random random = new Random(seed); |
| 35 | + |
| 36 | + for(int index = 0; index < octaveCount; index++) { |
| 37 | + |
| 38 | + this.octaves[index] = new SimplexNoiseOctave(random.nextInt()); |
| 39 | + this.frequencys[index] = Math.pow(2, index); |
| 40 | + this.amplitudes[index] = Math.pow(persistence, octaveCount - index); |
| 41 | + } |
| 42 | + } |
| 43 | + |
| 44 | + /** |
| 45 | + * Generates a height map. |
| 46 | + * @param x X coordinate |
| 47 | + * @param y Y coordinate |
| 48 | + * @param width width |
| 49 | + * @param height height |
| 50 | + * @return the generated height map |
| 51 | + */ |
| 52 | + public float[][] generateHeightMap(int x, int y, int width, int height) { |
| 53 | + |
| 54 | + int xEnd = x + width; |
| 55 | + int yEnd = y + height; |
| 56 | + |
| 57 | + float[][] result = new float[width][height]; |
| 58 | + |
| 59 | + for(int i = 0; i < width; i++) { |
| 60 | + |
| 61 | + for(int j = 0; j < height; j++) { |
| 62 | + |
| 63 | + int posX = x + i * ((xEnd - x) / width); |
| 64 | + int posY = y + j * ((yEnd - y) / height); |
| 65 | + result[i][j] = Math.min(1.0F, Math.max(0.0F, (float)(0.5D * (1 + this.getNoise(posX, posY))))); |
| 66 | + } |
| 67 | + } |
| 68 | + |
| 69 | + return result; |
| 70 | + } |
| 71 | + |
| 72 | + /** |
| 73 | + * Generates a two dimensional noise. |
| 74 | + * @param x X coordinate |
| 75 | + * @param y Y coordinate |
| 76 | + * @return the generated noise |
| 77 | + */ |
| 78 | + public double getNoise(int x, int y) { |
| 79 | + |
| 80 | + double result = 0; |
| 81 | + |
| 82 | + for(int index = 0; index < this.octaves.length; index++) { |
| 83 | + |
| 84 | + result += this.octaves[index].noise(x / this.frequencys[index], y / this.frequencys[index]) * this.amplitudes[index]; |
| 85 | + } |
| 86 | + |
| 87 | + return result; |
| 88 | + } |
| 89 | + |
| 90 | + /** |
| 91 | + * Generates a three dimensional noise. |
| 92 | + * @param x X coordinate |
| 93 | + * @param y Y coordinate |
| 94 | + * @param z Z coordinate |
| 95 | + * @return the generated noise |
| 96 | + */ |
| 97 | + public double getNoise(int x, int y, int z) { |
| 98 | + |
| 99 | + double result = 0; |
| 100 | + |
| 101 | + for(int index = 0; index < this.octaves.length; index++) { |
| 102 | + |
| 103 | + double frequency = Math.pow(2, index); |
| 104 | + double amplitude = Math.pow(this.persistance, this.octaves.length - index); |
| 105 | + |
| 106 | + result += this.octaves[index].noise(x / frequency, y / frequency, z / frequency) * amplitude; |
| 107 | + } |
| 108 | + |
| 109 | + return result; |
| 110 | + } |
| 111 | + |
| 112 | + /** |
| 113 | + * @return the largest possible feature |
| 114 | + */ |
| 115 | + public int getLargestFeature() { |
| 116 | + |
| 117 | + return this.largestFeature; |
| 118 | + } |
| 119 | + |
| 120 | + /** |
| 121 | + * @return the persistence |
| 122 | + */ |
| 123 | + public double getPersistance() { |
| 124 | + |
| 125 | + return this.persistance; |
| 126 | + } |
| 127 | + |
| 128 | + /** |
| 129 | + * @return the seed |
| 130 | + */ |
| 131 | + public long getSeed() { |
| 132 | + |
| 133 | + return this.seed; |
| 134 | + } |
| 135 | +} |
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