From 2541a6d96ca0393311eb0797a0de954f376824aa Mon Sep 17 00:00:00 2001
From: spatialfree <mail@ethanmerchant.com>
Date: Thu, 19 Dec 2024 04:08:11 -0500
Subject: [PATCH] noise rng maths

---
 src/Maths.cs | 121 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/VFX.cs   |   4 +-
 2 files changed, 122 insertions(+), 3 deletions(-)

diff --git a/src/Maths.cs b/src/Maths.cs
index ef31c57..0d54b69 100644
--- a/src/Maths.cs
+++ b/src/Maths.cs
@@ -35,7 +35,10 @@ public static class Maths
     // public static int roundi(float value) => MathF.Round(value)
 
     public static float precision(float x, float p)
-        => round(x * p) / p;
+    {
+        float ps = p < 1.0f ? 1 / p : p;
+        return round(x * ps) / ps;
+    }
 
     public static float smooth_start(float t) => (t * t * t);
     public static float smooth_stop(float t)
@@ -94,6 +97,122 @@ public static class Maths
     }
 }
 
+/// <summary>
+/// SquirrelNoise5 - Squirrel's Raw Noise utilities (version 5)
+/// Converted to C# from original C++ implementation by Squirrel Eiserloh
+/// </summary>
+public static class Noise
+{
+    // Bit noise constants
+    private const uint SQ5_BIT_NOISE1 = 0xd2a80a3f;
+    private const uint SQ5_BIT_NOISE2 = 0xa884f197;
+    private const uint SQ5_BIT_NOISE3 = 0x6C736F4B;
+    private const uint SQ5_BIT_NOISE4 = 0xB79F3ABB;
+    private const uint SQ5_BIT_NOISE5 = 0x1b56c4f5;
+
+    // Constants for higher dimensional noise
+    private const int PRIME1 = 198491317;
+    private const int PRIME2 = 6542989;
+    private const int PRIME3 = 357239;
+
+    /// <summary>
+    /// Fast hash of an int32 into a different (unrecognizable) uint32
+    /// </summary>
+    private static uint GetNoise(int positionX, uint seed)
+    {
+        uint mangledBits = (uint)positionX;
+        mangledBits *= SQ5_BIT_NOISE1;
+        mangledBits += seed;
+        mangledBits ^= (mangledBits >> 9);
+        mangledBits += SQ5_BIT_NOISE2;
+        mangledBits ^= (mangledBits >> 11);
+        mangledBits *= SQ5_BIT_NOISE3;
+        mangledBits ^= (mangledBits >> 13);
+        mangledBits += SQ5_BIT_NOISE4;
+        mangledBits ^= (mangledBits >> 15);
+        mangledBits *= SQ5_BIT_NOISE5;
+        mangledBits ^= (mangledBits >> 17);
+        return mangledBits;
+    }
+
+    // 1D Noise Functions
+    public static uint u_int_x(int x, uint seed = 0)
+    {
+        return GetNoise(x, seed);
+    }
+
+    public static float u_scalar_x(int x, uint seed = 0)
+    {
+        return (float)(GetNoise(x, seed) / (double)uint.MaxValue);
+    }
+
+    public static float s_scalar_x(int x, uint seed = 0)
+    {
+        return (float)((int)GetNoise(x, seed) / (double)int.MaxValue);
+    }
+
+    private static int step;
+    static int stepper
+    {
+        get
+        {
+            step = (step + 1) % 100_000; // [!] magic number
+            return step;
+        }
+    }
+    public static uint u_int => u_int_x(stepper);
+    public static float u_scalar => u_scalar_x(stepper);
+    public static float s_scalar => s_scalar_x(stepper);
+
+    // // 2D Noise Functions
+    // public static uint Get2dNoiseUint(int indexX, int indexY, uint seed = 0)
+    // {
+    //     return GetNoise(indexX + (PRIME1 * indexY), seed);
+    // }
+
+    // public static float Get2dNoiseZeroToOne(int indexX, int indexY, uint seed = 0)
+    // {
+    //     return (float)(Get2dNoiseUint(indexX, indexY, seed) / (double)uint.MaxValue);
+    // }
+
+    // public static float Get2dNoiseNegOneToOne(int indexX, int indexY, uint seed = 0)
+    // {
+    //     return (float)((int)Get2dNoiseUint(indexX, indexY, seed) / (double)int.MaxValue);
+    // }
+
+    // 3D Noise Functions
+    public static uint u_int_xyz(int x, int y, int z, uint seed = 0)
+    {
+        return GetNoise(x + (PRIME1 * y) + (PRIME2 * z), seed);
+    }
+
+    public static float u_scalar_xyz(int x, int y, int z, uint seed = 0)
+    {
+        return (float)(u_int_xyz(x, y, z, seed) / (double)uint.MaxValue);
+    }
+
+    public static float s_scalar_xyz(int x, int y, int z, uint seed = 0)
+    {
+        return (float)((int)u_int_xyz(x, y, z, seed) / (double)int.MaxValue);
+    }
+
+    // // 4D Noise Functions
+    // public static uint Get4dNoiseUint(int indexX, int indexY, int indexZ, int indexT, uint seed = 0)
+    // {
+    //     return GetNoise(indexX + (PRIME1 * indexY) + (PRIME2 * indexZ) + (PRIME3 * indexT), seed);
+    // }
+
+    // public static float Get4dNoiseZeroToOne(int indexX, int indexY, int indexZ, int indexT, uint seed = 0)
+    // {
+    //     return (float)(Get4dNoiseUint(indexX, indexY, indexZ, indexT, seed) / (double)uint.MaxValue);
+    // }
+
+    // public static float Get4dNoiseNegOneToOne(int indexX, int indexY, int indexZ, int indexT, uint seed = 0)
+    // {
+    //     return (float)((int)Get4dNoiseUint(indexX, indexY, indexZ, indexT, seed) / (double)int.MaxValue);
+    // }
+}
+
 public class DeltaBool
 {
     public int delta = 0;
diff --git a/src/VFX.cs b/src/VFX.cs
index adcb901..a57f225 100644
--- a/src/VFX.cs
+++ b/src/VFX.cs
@@ -23,9 +23,9 @@ static class VFX
             index = (index + 1) % particles.Length;
             Particle particle = particles[index];
             particle.pos = pos;
-            particle.vel = Quat.FromAngles(Random.Shared.NextSingle() * 360, 0, 0) * Quat.FromAngles(0, Random.Shared.NextSingle() * 360, 0) * Vec3.Forward * 3.0f;
+            particle.vel = Quat.FromAngles(Noise.u_scalar * 360, 0, 0) * Quat.FromAngles(0, Noise.u_scalar * 360, 0) * Vec3.Forward * 3.0f;
             particle.ori = Quat.Identity;
-            particle.scl = (1.0f / 3) * Maths.smooth_start(Random.Shared.NextSingle());
+            particle.scl = (1.0f / 3) * Maths.smooth_start(Noise.u_scalar);
         }
     }