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121 lines
3.4 KiB
121 lines
3.4 KiB
/*==LICENSE==* |
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CyanWorlds.com Engine - MMOG client, server and tools |
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Copyright (C) 2011 Cyan Worlds, Inc. |
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This program is free software: you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation, either version 3 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with this program. If not, see <http://www.gnu.org/licenses/>. |
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You can contact Cyan Worlds, Inc. by email legal@cyan.com |
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or by snail mail at: |
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Cyan Worlds, Inc. |
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14617 N Newport Hwy |
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Mead, WA 99021 |
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*==LICENSE==*/ |
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#ifndef plRandom_inc |
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#define plRandom_inc |
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// FAST_Q is basically lifted from Numerical Recipes. |
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// The RandZeroToOne and RandMinusOneToOne were "enhanced" |
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// a bit, but tested out nicely to generate sequences with |
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// appropriate maxs, mins, and means. |
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// FAST_Q depends on IEEE floating point format. Undefine |
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// it for any platform which doesn't satisfy this, or |
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// come up with the appropriate constants for that platform. |
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#define FAST_Q |
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class plRandom |
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{ |
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protected: |
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mutable UInt32 fSeed; |
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public: |
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inline float RandNorm() const; |
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inline int Rand() const; |
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inline int RandRangeI(int lo, int hi) const; |
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inline float RandRangeF(float lo, float hi) const; |
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inline float RandMinusOneToOne() const; |
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inline float RandZeroToOne() const; |
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UInt32 GetSeed() const { return fSeed; } |
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void SetSeed(int seed) { fSeed = seed; } |
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plRandom(int seed = 1) : fSeed(seed) {} |
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}; |
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inline float plRandom::RandNorm() const |
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{ |
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#ifndef FAST_Q |
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return 1.f / 32767.f; |
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#else // FAST_Q |
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return (1.f / float(~0UL)); |
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#endif // FAST_Q |
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} |
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inline int plRandom::Rand() const |
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{ |
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#ifndef FAST_Q |
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register int temp; |
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fSeed = fSeed * 1103515245 + 12345; |
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temp = (int)((fSeed/65536)&32767); |
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return (temp); |
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#else // FAST_Q |
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return fSeed = 1664525L * fSeed + 1013904223L; |
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#endif // FAST_Q |
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} |
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// RandZeroToOne - take our usual random UInt32. |
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// We're going to mask in an exponent to make it |
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// a float in range [1..2). Then subtract 1.f to |
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// make it [0..1). We shift our random UInt32 down |
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// by 9 because the upper bits are the most random. |
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inline float plRandom::RandZeroToOne() const |
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{ |
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#ifndef FAST_Q |
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return Rand() * RandNorm(); |
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#else // FAST_Q |
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const UInt32 kOneExp = 0x3f800000; |
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register UInt32 temp = kOneExp | (UInt32(Rand()) >> 9); |
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return (*(float*)&temp) - 1.f; |
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#endif // FAST_Q |
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} |
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// RandMinusOneToOne - same as RandZeroToOne, but we |
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// mask in an exponent putting it in range [2..4), |
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// then subtract 3 to give [-1..1). |
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inline float plRandom::RandMinusOneToOne() const |
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{ |
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#ifndef FAST_Q |
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return RandZeroToOne() * 2.f - 1.f; |
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#else // FAST_Q |
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const UInt32 kTwoExp = 0x40000000; |
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register UInt32 temp = kTwoExp | (UInt32(Rand()) >> 9); |
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return (*(float*)&temp) - 3.f; |
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#endif // FAST_Q |
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} |
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inline float plRandom::RandRangeF(float lo, float hi) const |
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{ |
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return lo + RandZeroToOne() * (hi - lo); |
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} |
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inline int plRandom::RandRangeI(int lo, int hi) const |
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{ |
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return lo + int(RandZeroToOne() * float(hi + 1 - lo)); |
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} |
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#endif // plRandom_inc |
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