40 lines
940 B
C++
40 lines
940 B
C++
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// Copyright 2020 Phyronnaz
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#include "FastNoise/VoxelFastNoiseLUT.h"
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#include "FastNoise/CrossPlatformSTD.h"
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#include <random>
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void FVoxelFastNoiseLUT::SetSeed(int32 NewSeed)
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{
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VOXEL_ASYNC_FUNCTION_COUNTER();
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Seed = NewSeed;
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std::mt19937 Generator(NewSeed);
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// There is a bug below:
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// 256 - j should be 255 - j
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// However, fixing it would break all existing generators
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// Instead, make sure it's deterministic
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Perm.Memzero();
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Perm12.Memzero();
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for (int32 Index = 0; Index < 256; Index++)
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{
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Perm[Index] = Index;
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}
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for (int32 j = 0; j < 256; j++)
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{
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cross_platform_std::uniform_int_distribution<> Distribution(0, 256 - j); // <- bug here
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// K should be max 255
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// Due to the bug it's max 256
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// m_perm.Num() = 512, so it's fine to do m_perm[k]
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int32 k = Distribution(Generator) + j;
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int32 l = Perm[j];
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Perm[j] = Perm[j + 256] = Perm[k];
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Perm[k] = l;
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Perm12[j] = Perm12[j + 256] = Perm[j] % 12;
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}
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}
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