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Small speed improvement by storing variables separately (rather than in Vector3D) to void construction/comparison overhead.

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This commit is contained in:
David Williams 2015-03-09 23:52:56 +01:00
parent 99d0a226c8
commit 741234e4a5
2 changed files with 20 additions and 6 deletions
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12
include/PolyVox/PagedVolume.h
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@ -283,11 +283,19 @@ namespace PolyVox
private:
Chunk* getChunk(int32_t uChunkX, int32_t uChunkY, int32_t uChunkZ) const;
// Storing these properties individually has proved to be faster than keeping
// them in a Vector3DInt32 as it avoids constructions and comparison overheads.
// They are also at the start of the class in the hope that they will be pulled
// into cache - I've got no idea if this actually makes a difference.
mutable int32_t m_v3dLastAccessedChunkX = 0;
mutable int32_t m_v3dLastAccessedChunkY = 0;
mutable int32_t m_v3dLastAccessedChunkZ = 0;
mutable Chunk* m_pLastAccessedChunk = nullptr;
mutable std::unordered_map<Vector3DInt32, std::unique_ptr< Chunk > > m_mapChunks;
mutable uint32_t m_uTimestamper = 0;
mutable Vector3DInt32 m_v3dLastAccessedChunkPos = Vector3DInt32(0, 0, 0); //There are no invalid positions, but initially the m_pLastAccessedChunk pointer will be null
mutable Chunk* m_pLastAccessedChunk = nullptr;
uint32_t m_uChunkCountLimit = 0;
// The size of the volume

14
include/PolyVox/PagedVolume.inl
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@ -259,17 +259,20 @@ namespace PolyVox
template <typename VoxelType>
typename PagedVolume<VoxelType>::Chunk* PagedVolume<VoxelType>::getChunk(int32_t uChunkX, int32_t uChunkY, int32_t uChunkZ) const
{
Vector3DInt32 v3dChunkPos(uChunkX, uChunkY, uChunkZ);
//Check if we have the same chunk as last time, if so there's no need to even update
//the time stamp. If we updated it everytime then that would be every time we touched
//a voxel, which would overflow a uint32_t and require us to use a uint64_t instead.
//This check should also provide a significant speed boost as usually it is true.
if((v3dChunkPos == m_v3dLastAccessedChunkPos) && (m_pLastAccessedChunk != 0))
if ((uChunkX == m_v3dLastAccessedChunkX) &&
(uChunkY == m_v3dLastAccessedChunkY) &&
(uChunkZ == m_v3dLastAccessedChunkZ) &&
(m_pLastAccessedChunk != 0))
{
return m_pLastAccessedChunk;
}
Vector3DInt32 v3dChunkPos(uChunkX, uChunkY, uChunkZ);
// The chunk was not the same as last time, but we can now hope it is in the set of most recently used chunks.
Chunk* pChunk = nullptr;
auto itChunk = m_mapChunks.find(v3dChunkPos);
@ -309,7 +312,10 @@ namespace PolyVox
}
m_pLastAccessedChunk = pChunk;
m_v3dLastAccessedChunkPos = v3dChunkPos;
//m_v3dLastAccessedChunkPos = v3dChunkPos;
m_v3dLastAccessedChunkX = uChunkX;
m_v3dLastAccessedChunkY = uChunkY;
m_v3dLastAccessedChunkZ = uChunkZ;
return pChunk;
}