StdRand.hpp

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    Copyright (c) 2009-2010 Christopher A. Taylor.  All rights reserved.

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#ifndef CAT_STDRAND_HPP
#define CAT_STDRAND_HPP

#include <cat/Platform.hpp>

namespace cat {


// Microsoft VC++ 7.0 stdlib srand(), rand(), old RANDU()
class StandardRand
{
protected:
    s32 seed;

public:
    StandardRand(u32 ns = 0) { seed = ns; }

    inline void srand32(u32 ns) { seed = ns; } // 32-bit version
    inline void srand16(u16 ns) { seed = ns; } // 16-bit version (yup)

    u16 rand();     // Linear Congruential Generator: X = X * M + A (mod N)
    u16 randu();    // RANDU LCG: X = X * M (mod N)
    float sfrand(); // Fast [-1.f,1.f] generator from Inigo Quilez (2005)
};


// Non-linear congruential 32-bit random mixing function for given x, y and seed
// This function is used in every example of Perlin noise I found online for some reason!
u32 NLCRand32(int x, int y, u32 seed);

// Uses NLCRand32 as a front-end, and then maps the output to a number between -1 and 1
float NLCRandNorm(int x, int y, u32 seed);



} // namespace cat

#endif // CAT_STDRAND_HPP