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Source/Engine/Utilities/PerlinNoise.cs

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+using System;
+
+namespace FlaxEngine.Utilities
+{
+    /// <summary>
+    /// Helper class for Perlin Noise generation.
+    /// </summary>
+    [HideInEditor]
+    public class PerlinNoise
+    {
+        /// <summary>
+        /// The base value.
+        /// </summary>
+        private float Base;
+
+        /// <summary>
+        /// The noise scale parameter.
+        /// </summary>
+        public float NoiseScale;
+
+        /// <summary>
+        /// The noise amount parameter.
+        /// </summary>
+        public float NoiseAmount;
+
+        /// <summary>
+        /// The noise octaves count.
+        /// </summary>
+        public int Octaves;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PerlinNoise"/> class.
+        /// </summary>
+        /// <param name="baseValue">The base value.</param>
+        /// <param name="scale">The noise scale.</param>
+        /// <param name="amount">The noise amount.</param>
+        /// <param name="octaves">The noise octaves count.</param>
+        public PerlinNoise(float baseValue, float scale, float amount, int octaves = 4)
+        {
+            Base = baseValue;
+            NoiseScale = scale;
+            NoiseAmount = amount;
+            Octaves = octaves;
+        }
+
+        /// <summary>
+        /// Samples the Perlin Noise at the given location (integer coordinates).
+        /// </summary>
+        /// <param name="x">The x coordinate.</param>
+        /// <param name="y">The y coordinate.</param>
+        /// <returns>The noise value.</returns>
+        public float Sample(int x, int y)
+        {
+            float noise = 0.0f;
+
+            if (NoiseScale > Mathf.Epsilon)
+            {
+                x = Math.Abs(x);
+                y = Math.Abs(y);
+
+                for (int octave = 0; octave < Octaves; octave++)
+                {
+                    float octaveShift = 1 << octave;
+                    float octaveScale = octaveShift / NoiseScale;
+                    noise += PerlinNoise2D(x * octaveScale, y * octaveScale) / octaveShift;
+                }
+            }
+
+            return Base + noise * NoiseAmount;
+        }
+
+        private float Fade(float T)
+        {
+            return T * T * T * (T * (T * 6 - 15) + 10);
+        }
+
+        private float Grad(int hash, float x, float y)
+        {
+            int h = hash & 15;
+            float u = h < 8 || h == 12 || h == 13 ? x : y,
+                  v = h < 4 || h == 12 || h == 13 ? y : 0;
+            return ((h & 1) == 0 ? u : -u) + ((h & 2) == 0 ? v : -v);
+        }
+
+        private float PerlinNoise2D(float x, float y)
+        {
+            int truncX = Mathf.FloorToInt(x),
+                truncY = Mathf.FloorToInt(y),
+                intX = truncX & 255,
+                intY = truncY & 255;
+            float fracX = x - truncX,
+                  fracY = y - truncY;
+
+            float u = Fade(fracX),
+                  v = Fade(fracY);
+
+            int a = Permutations[intX] + intY,
+                aa = Permutations[a & 255],
+                ab = Permutations[(a + 1) & 255],
+                b = Permutations[(intX + 1) & 255] + intY,
+                ba = Permutations[b & 255],
+                bb = Permutations[(b + 1) & 255];
+
+            return Mathf.Lerp(Mathf.Lerp(Grad(Permutations[aa], fracX, fracY),
+                                         Grad(Permutations[ba], fracX - 1, fracY), u),
+                              Mathf.Lerp(Grad(Permutations[ab], fracX, fracY - 1),
+                                         Grad(Permutations[bb], fracX - 1, fracY - 1), u), v);
+        }
+
+        private static readonly int[] Permutations =
+        {
+            151, 160, 137, 91, 90, 15,
+            131, 13, 201, 95, 96, 53, 194, 233, 7, 225, 140, 36, 103, 30, 69, 142, 8, 99, 37, 240, 21, 10, 23,
+            190, 6, 148, 247, 120, 234, 75, 0, 26, 197, 62, 94, 252, 219, 203, 117, 35, 11, 32, 57, 177, 33,
+            88, 237, 149, 56, 87, 174, 20, 125, 136, 171, 168, 68, 175, 74, 165, 71, 134, 139, 48, 27, 166,
+            77, 146, 158, 231, 83, 111, 229, 122, 60, 211, 133, 230, 220, 105, 92, 41, 55, 46, 245, 40, 244,
+            102, 143, 54, 65, 25, 63, 161, 1, 216, 80, 73, 209, 76, 132, 187, 208, 89, 18, 169, 200, 196,
+            135, 130, 116, 188, 159, 86, 164, 100, 109, 198, 173, 186, 3, 64, 52, 217, 226, 250, 124, 123,
+            5, 202, 38, 147, 118, 126, 255, 82, 85, 212, 207, 206, 59, 227, 47, 16, 58, 17, 182, 189, 28, 42,
+            223, 183, 170, 213, 119, 248, 152, 2, 44, 154, 163, 70, 221, 153, 101, 155, 167, 43, 172, 9,
+            129, 22, 39, 253, 19, 98, 108, 110, 79, 113, 224, 232, 178, 185, 112, 104, 218, 246, 97, 228,
+            251, 34, 242, 193, 238, 210, 144, 12, 191, 179, 162, 241, 81, 51, 145, 235, 249, 14, 239, 107,
+            49, 192, 214, 31, 181, 199, 106, 157, 184, 84, 204, 176, 115, 121, 50, 45, 127, 4, 150, 254,
+            138, 236, 205, 93, 222, 114, 67, 29, 24, 72, 243, 141, 128, 195, 78, 66, 215, 61, 156, 180
+        };
+    }
+}