mirror of
https://github.com/love2d/love.git
synced 2026-08-12 16:40:57 +02:00
Alex Szpakowski
0447d1e7c5
Changed love.math.randomseed(seed) to love.math.setRandomState(state) and love.math.setRandomState(low, high). Added low, high = love.math.getRandomState(). love.math.setRandomState(state) can set the random state to an integer of up to 53 bits, love.math.setRandomState(low, high) can set the random state to a 64 bit integer by using the first argument as the lower 32 bits and the second argument as the higher 32 bits. This allows for reliable setting and saving of the state of a RNG. --HG-- branch : RandomGenerator-2
76 lines
2.2 KiB
C++
76 lines
2.2 KiB
C++
/**
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* Copyright (c) 2006-2013 LOVE Development Team
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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**/
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#include "RandomGenerator.h"
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// STL
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#include <cmath>
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namespace love
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{
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namespace math
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{
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// 64 bit Xorshift implementation taken from the end of Sec. 3 (page 4) in
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// George Marsaglia, "Xorshift RNGs", Journal of Statistical Software, Vol.8 (Issue 14), 2003
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RandomGenerator::RandomGenerator()
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: last_randomnormal(std::numeric_limits<double>::infinity())
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{
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// because it is too big for some compilers to handle ... if you know what
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// i mean
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#ifdef LOVE_BIG_ENDIAN
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rng_state.b32.a = 0x0139408D;
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rng_state.b32.b = 0xCBBF7A44;
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#else
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rng_state.b32.b = 0x0139408D;
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rng_state.b32.a = 0xCBBF7A44;
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#endif
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}
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uint64 RandomGenerator::rand()
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{
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rng_state.b64 ^= (rng_state.b64 << 13);
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rng_state.b64 ^= (rng_state.b64 >> 7);
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rng_state.b64 ^= (rng_state.b64 << 17);
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return rng_state.b64;
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}
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// Box–Muller transform
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double RandomGenerator::randomNormal(double stddev)
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{
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// use cached number if possible
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if (last_randomnormal != std::numeric_limits<double>::infinity())
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{
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double r = last_randomnormal;
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last_randomnormal = std::numeric_limits<double>::infinity();
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return r * stddev;
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}
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double r = sqrt(-2.0 * log(1. - random()));
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double phi = 2.0 * LOVE_M_PI * (1. - random());
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last_randomnormal = r * cos(phi);
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return r * sin(phi) * stddev;
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}
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} // math
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} // love
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