it kinda work

Project Reboot 3.0/RandomStream.h

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+#pragma once
+
+#include "inc.h"
+
+struct FRandomStream
+{
+public:
+
+	/**
+	 * Default constructor.
+	 *
+	 * The seed should be set prior to use.
+	 */
+	FRandomStream()
+		: InitialSeed(0)
+		, Seed(0)
+	{ }
+
+	/**
+	 * Creates and initializes a new random stream from the specified seed value.
+	 *
+	 * @param InSeed The seed value.
+	 */
+	FRandomStream(int32 InSeed)
+	{
+		Initialize(InSeed);
+	}
+
+public:
+
+	/**
+	 * Initializes this random stream with the specified seed value.
+	 *
+	 * @param InSeed The seed value.
+	 */
+	void Initialize(int32 InSeed)
+	{
+		InitialSeed = InSeed;
+		Seed = uint32(InSeed);
+	}
+
+	float GetFraction() const
+	{
+		MutateSeed();
+
+		float Result;
+
+		*(uint32*)&Result = 0x3F800000U | (Seed >> 9);
+
+		return Result - 1.0f;
+	}
+
+	FORCEINLINE float FRand() const
+	{
+		return GetFraction();
+	}
+
+protected:
+
+	/**
+	 * Mutates the current seed into the next seed.
+	 */
+	void MutateSeed() const
+	{
+		Seed = (Seed * 196314165U) + 907633515U;
+	}
+
+private:
+
+	// Holds the initial seed.
+	int32 InitialSeed;
+
+	// Holds the current seed. This should be an uint32 so that any shift to obtain top bits
+	// is a logical shift, rather than an arithmetic shift (which smears down the negative bit).
+	mutable uint32 Seed;
+};