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author | Alexander Harkness <bearbin@gmail.com> | 2013-11-24 15:19:41 +0100 |
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committer | Alexander Harkness <bearbin@gmail.com> | 2013-11-24 15:19:41 +0100 |
commit | 675b4aa878f16291ce33fced48a2bc7425f635ae (patch) | |
tree | 409914df27a98f65adf866da669429c4de141b6f /src/FastRandom.h | |
parent | LineBlockTracer: Using the coord-based block faces. (diff) | |
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Diffstat (limited to 'src/FastRandom.h')
-rw-r--r-- | src/FastRandom.h | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/src/FastRandom.h b/src/FastRandom.h new file mode 100644 index 000000000..bf70822cf --- /dev/null +++ b/src/FastRandom.h @@ -0,0 +1,57 @@ + +// FastRandom.h + +// Declares the cFastRandom class representing a fast random number generator + +/* +The cFastRandom aims to provide a very fast, although not very cryptographically secure, random generator. +It is fast to instantiate, fast to query next, and partially multi-thread-safe. +It is multi-thread-safe in the sense that it can be accessed from multiple threads without crashing, but it may +yield duplicate numbers in that case. + +Internally, this works similar to cNoise's integral noise generation, with some predefined inputs: the seed is +taken from a global counter and the random is calculated using a counter that is incremented on each use (hence +the multi-thread duplication). Two alternatives exists for each function, one that takes a range parameter, +and another that takes an additional "salt" parameter; this salt is used as an additional input to the random, +in order to avoid multi-thread duplication. If two threads both use the class at the same time with different +salts, the values they get will be different. +*/ + + + + + +#pragma once + + + + + +class cFastRandom +{ +public: + cFastRandom(void); + + /// Returns a random int in the range [0 .. a_Range - 1]; a_Range must be less than 1M + int NextInt(int a_Range); + + /// Returns a random int in the range [0 .. a_Range - 1]; a_Range must be less than 1M; a_Salt is additional source of randomness + int NextInt(int a_Range, int a_Salt); + + /// Returns a random float in the range [0 .. a_Range]; a_Range must be less than 1M + float NextFloat(float a_Range); + + /// Returns a random float in the range [0 .. a_Range]; a_Range must be less than 1M; a_Salt is additional source of randomness + float NextFloat(float a_Range, int a_Salt); + +protected: + int m_Seed; + int m_Counter; + + /// Counter that is used to initialize the seed, incremented for each object created + static int m_SeedCounter; +} ; + + + + |