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Torque/SDK/lib/maxsdk40/RandGenerator.h

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+/**********************************************************************
+ *<
+	FILE: RandGenerator.h
+
+	DESCRIPTION: Generator of random numbers
+
+	CREATED BY: Oleg Bayborodin
+
+	HISTORY: Nov.17 2000 - created
+
+	GOALS: To solve the need in satisfactory generator of random numbers.
+
+	DESCRIPTION: The class has interfaces for srand/rand methods of VC++ 
+		and other functions for random number generation.
+
+		Srand/rand methods from stdlib.h have two main problems:
+		a) It's not satisfactory random. Since rand() function returns a 
+			pseudorandom integer in the range 0 to 0x7fff=32767, if we
+			need a lot of random numbers (i.e. for generating 100,000 
+			particles), we are running out of continuity of random num-
+			bers. Generated random numbers became too discrete.
+		b) rand() method is global function, not class object. Hence it's
+			shared between all modules of your plug-in. Changes in one
+			module may change randomness pattern in other independent 
+			module. To solve this contradiction, rand methods have to be
+			implemented as a class object.
+
+		RandGenerator does exactly that. It has much more random numbers:
+		RAND_MAX = 0xFFFFFFFF = 4,294,967,295. Also, using instance of 
+		the class, it's much easier to create separate thread of random 
+		numbers for specific module.
+
+ *>	Copyright (c) 2000, All Rights Reserved.
+ **********************************************************************/
+
+#ifndef _RANDGENERATOR_H 
+
+#define _RANDGENERATOR_H 
+
+
+// to fix conflict between RandGenerator and stdlib.h do the following:
+#undef RAND_MAX
+const unsigned int RAND_MAX = 0x7fff; // as defined in stdlib.h
+
+class RandGenerator 
+{
+	public:
+		CoreExport RandGenerator(); // constructor
+	
+	// override for VC++ rand methods
+		CoreExport static const DWORD32 RAND_MAX;
+
+		// The srand function sets the starting point for generating a 
+		// series of pseudorandom integers. To reinitialize the generator, 
+		// use 1 as the seed argument. Any other value for seed sets the 
+		// generator to a random starting point. rand() retrieves the 
+		// pseudorandom numbers that are generated. Calling rand() before 
+		// any call to srand() generates the same sequence as calling srand() 
+		// with seed passed as 1.
+		CoreExport void	srand(DWORD32 seed);
+		// The rand function returns a pseudorandom integer in the range 0 to RAND_MAX
+		CoreExport DWORD32 rand( void );
+
+	// other useful functions:
+		// random sign { -1, 1 }
+		CoreExport int		RandSign( void );
+		// random number between 0.0f and 1.0f
+		CoreExport float	Rand01( void );
+		// random number between -1.0f and 1.0f
+		CoreExport float	Rand11( void );
+		// random number between -0.5f and 0.5f
+		CoreExport float	Rand55( void );
+		// integer random number between 0 and maxnum
+		CoreExport int		Rand0X(int maxnum);
+
+	// to check out if the generator has been explicitely initialized
+	// by srand() method
+		const bool	Valid( void ) const { return m_explicitelyInitialized; }
+
+	private:
+		static const DWORD32 kMagicNumber1, kMagicNumber2;
+		static const DWORD32 HALF_RAND_MAX;
+		static const double kIntMax, kIntMax1, kHalfIntMax;
+		DWORD32 m_randar[256];
+		DWORD32 m_randX, m_randY;
+		bool m_explicitelyInitialized;
+};
+
+
+
+#endif