Implemented cubic noise

CubicNoise/Noisers/CubicNoiseEngine.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Runtime.CompilerServices;
 using System.Text;
 using CubicNoise.Contracts;
 
@@ -7,23 +8,89 @@ namespace CubicNoise.Noisers
 {
     public sealed class CubicNoiseEngine : INoiseEngine
     {
-        private Dictionary<IParameterName, int> intParameters;
+        private const int RANDOM_NUMBER_A =   134_775_813;
+        private const int RANDOM_NUMBER_B = 1_103_515_245;
+
+        private readonly int octave;
+        private readonly int periodX;
+        private readonly int periodY;
         private int seed;
 
         public CubicNoiseEngine(int seed, Dictionary<IParameterName, int> intParameters)
         {
-            this.intParameters = intParameters;
             this.seed = seed;
+            this.octave = intParameters?.ContainsKey(CubicNoiseIntParameters.OCTAVE) == true ? intParameters[CubicNoiseIntParameters.OCTAVE] : 16;
+            this.periodX = intParameters?.ContainsKey(CubicNoiseIntParameters.PERIOD_X) == true ? intParameters[CubicNoiseIntParameters.PERIOD_X] : 1_000;
+            this.periodY = intParameters?.ContainsKey(CubicNoiseIntParameters.PERIOD_Y) == true ? intParameters[CubicNoiseIntParameters.PERIOD_Y] : 512;
         }
 
         public float Get(float x)
         {
-            throw new NotImplementedException();
+            var xi = (int)Math.Floor(x / this.octave);
+            var octaveXFactor = x / this.octave - xi;
+
+            return this.Interpolation(
+                       a: this.RandomNumberGenerator(x: this.DeterminePatch(xi - 1, this.periodX), y: 0),
+                       b: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 0, this.periodX), y: 0),
+                       c: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 1, this.periodX), y: 0),
+                       d: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 2, this.periodX), y: 0),
+                       x: octaveXFactor) * 0.5f + 0.25f;
         }
 
         public float Get(float x, float y)
         {
-            throw new NotImplementedException();
+            var xi = (int)Math.Floor(x / octave);
+            var yi = (int)Math.Floor(y / octave);
+
+            var octaveXFactor = x / octave - xi;
+            var octaveYFactor = y / octave - yi;
+
+            return this.Interpolation(
+                       a: this.Interpolation(
+                           a: this.RandomNumberGenerator(x: this.DeterminePatch(xi - 1, this.periodX), y: this.DeterminePatch(yi - 1 + 0, this.periodY)),
+                           b: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 0, this.periodX), y: this.DeterminePatch(yi - 1 + 0, this.periodY)),
+                           c: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 1, this.periodX), y: this.DeterminePatch(yi - 1 + 0, this.periodY)),
+                           d: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 2, this.periodX), y: this.DeterminePatch(yi - 1 + 0, this.periodY)),
+                           x: octaveXFactor),
+
+                       b: this.Interpolation(
+                           a: this.RandomNumberGenerator(x: this.DeterminePatch(xi - 1, this.periodX), y: this.DeterminePatch(yi - 1 + 1, this.periodY)),
+                           b: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 0, this.periodX), y: this.DeterminePatch(yi - 1 + 1, this.periodY)),
+                           c: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 1, this.periodX), y: this.DeterminePatch(yi - 1 + 1, this.periodY)),
+                           d: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 2, this.periodX), y: this.DeterminePatch(yi - 1 + 1, this.periodY)),
+                           x: octaveXFactor),
+
+                       c: this.Interpolation(
+                           a: this.RandomNumberGenerator(x: this.DeterminePatch(xi - 1, this.periodX), y: this.DeterminePatch(yi - 1 + 2, this.periodY)),
+                           b: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 0, this.periodX), y: this.DeterminePatch(yi - 1 + 2, this.periodY)),
+                           c: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 1, this.periodX), y: this.DeterminePatch(yi - 1 + 2, this.periodY)),
+                           d: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 2, this.periodX), y: this.DeterminePatch(yi - 1 + 2, this.periodY)),
+                           x: octaveXFactor),
+
+                       d: this.Interpolation(
+                           a: this.RandomNumberGenerator(x: this.DeterminePatch(xi - 1, this.periodX), y: this.DeterminePatch(yi - 1 + 3, this.periodY)),
+                           b: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 0, this.periodX), y: this.DeterminePatch(yi - 1 + 3, this.periodY)),
+                           c: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 1, this.periodX), y: this.DeterminePatch(yi - 1 + 3, this.periodY)),
+                           d: this.RandomNumberGenerator(x: this.DeterminePatch(xi + 2, this.periodX), y: this.DeterminePatch(yi - 1 + 3, this.periodY)),
+                           x: octaveXFactor),
+
+                       x: octaveYFactor) * 0.5f + 0.25f;
+        }
+
+        private float RandomNumberGenerator(int x, int y)
+        {
+            return (float)((((x ^ y) * RANDOM_NUMBER_A) ^ (this.seed + x)) * (((RANDOM_NUMBER_B * x) << 16) ^ (RANDOM_NUMBER_B * y) - RANDOM_NUMBER_A)) / int.MaxValue;
+        }
+
+        private int DeterminePatch(int coordinate, int period)
+        {
+            return coordinate % period;
+        }
+
+        private float Interpolation(float a, float b, float c, float d, float x)
+        {
+            var p = (d - c) - (a - b);
+            return x * (x * (x * p + ((a - b) - p)) + (c - a)) + b;
         }
     }
 }