Initial commit

Assets/Procedural Worlds/Gaia/Scripts/Utils/XorshiftPlus.cs

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+using UnityEngine;
+using System.Collections;
+
+namespace Gaia
+{
+    /// <summary>
+    /// Simple and fast random number generator which can reset to a specific iteration
+    /// </summary>
+    public class XorshiftPlus
+    {
+        //Initialiser magic values
+        private const ulong m_A_Init = 181353;
+        private const ulong m_B_Init = 7;
+
+        //Seed
+        public int m_seed;
+
+        //State
+        public ulong m_stateA, m_stateB;
+
+        /// <summary>
+        /// Contruct and initialise the RNG
+        /// </summary>
+        /// <param name="seed"></param>
+        public XorshiftPlus(int seed = 1)
+	    {
+            m_seed = seed;
+            if (m_seed == 0)
+            {
+                m_seed = 1;
+            }
+            Reset();
+	    }
+
+	    /// <summary>
+	    /// Reset it to its initial state with the existing seed
+	    /// </summary>
+        public void Reset()
+        {
+            m_stateA = m_A_Init * (uint)m_seed;
+            m_stateB = m_B_Init * (uint)m_seed;
+        }
+
+        /// <summary>
+        /// Restet it to a new state with a new seed
+        /// </summary>
+        /// <param name="seed">New seed</param>
+        public void Reset(int seed)
+        {
+            m_seed = seed;
+            if (m_seed == 0)
+            {
+                m_seed = 1;
+            }
+            Reset();
+        }
+
+        /// <summary>
+        /// Reset it to the stade defined by the state variables passed in
+        /// </summary>
+        public void Reset(ulong stateA, ulong stateB)
+        {
+            Debug.Log("Resetting RNG State " + stateA + " " + stateB);
+            m_stateA = stateA;
+            m_stateB = stateB;
+        }
+
+        /// <summary>
+        /// Return the current state for serialisation
+        /// </summary>
+        /// <param name="seed">Seed</param>
+        /// <param name="stateA">State A</param>
+        /// <param name="stateB">State B</param>
+        public void GetState(out int seed, out ulong stateA, out ulong stateB)
+        {
+            seed = m_seed;
+            stateA = m_stateA;
+            stateB = m_stateB;
+        }
+
+        //Check here for wrapper functions
+        //https://github.com/tucano/UnityRandom/blob/master/lib/MersenneTwister.cs
+
+        /// <summary>
+        /// Get the next value
+        /// </summary>
+        /// <returns>A value between zero and one inclusive</returns>
+	    public float Next()
+	    {
+		    ulong x = m_stateA;
+		    ulong y = m_stateB;
+		    m_stateA = y;
+		    x ^= x << 23;
+		    x ^= x >> 17;
+		    x ^= y ^ (y >> 26);
+		    m_stateB = x;
+            return (float)(x + y) / (float)ulong.MaxValue;
+	    }
+
+        /// <summary>
+        /// Return the next int
+        /// </summary>
+        /// <returns></returns>
+        public int NextInt()
+        {
+            return (int)(Next() * int.MaxValue);
+        }
+
+        /// <summary>
+        /// Get the next value and scale it between the min and max values supplied inclusive
+        /// </summary>
+        /// <param name="min">Minimum value</param>
+        /// <param name="max">Maximum value</param>
+        /// <returns>Next value scaled beteen the range supplied</returns>
+        public float Next(float min, float max)
+        {
+            //float xx = min + (Next() * (max - min));
+            //Debug.Log(string.Format("{0:0.0000}", xx));
+            //return xx;
+
+            return min + (Next() * (max - min));
+        }
+
+        /// <summary>
+        /// Get the next value and scale it between the min and max values supplied inclusive
+        /// </summary>
+        /// <param name="min">Minimum value</param>
+        /// <param name="max">Maximum value</param>
+        /// <returns>Next value scaled beteen the range supplied</returns>
+        public int Next(int min, int max)
+        {
+            if (min == max)
+            {
+                return min;
+            }
+            return (int)Next((float)min, (float)max+0.999f);
+        }
+
+        /// <summary>
+        /// Get the next value as a vector
+        /// </summary>
+        /// <returns>Next value as a vector in ranges 0..1</returns>
+        public Vector3 NextVector()
+        {
+            return new Vector3(Next(), Next(), Next());
+        }
+
+        /// <summary>
+        /// Get the next value as a vector
+        /// </summary>
+        /// <param name="min">Minimum value</param>
+        /// <param name="max">Maximum value</param>
+        /// <returns></returns>
+        public Vector3 NextVector(float min, float max)
+        {
+            return new Vector3(Next(min, max), Next(min, max), Next(min, max));
+        }
+    }
+}