AnotherFoxGuy/polyvox
1
0
Fork 0
Code Issues Pull Requests Activity

Revert "New, safer method of packing which makes careful use of casting to avoid problems with e.g. signed integer sign extension."

Browse Source 
This reverts commit fd451be2dd.
This commit is contained in:
David Williams
2015-03-21 14:40:11 +01:00
parent fd451be2dd
commit f574563672
2 changed files with 6 additions and 44 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
include/PolyVox/PagedVolume.h
View File

@@ -285,36 +285,17 @@ namespace PolyVox
ChunkKey posToChunkKey(int32_t iXPos, int32_t iYPos, int32_t iZPos) const
{
int32_t iBlockX = iXPos >> m_uChunkSideLengthPower;
int32_t iBlockY = iYPos >> m_uChunkSideLengthPower;
int32_t iBlockZ = iZPos >> m_uChunkSideLengthPower;
int16_t iBlockXAsInt16 = static_cast<int16_t>(iBlockX);
int16_t iBlockYAsInt16 = static_cast<int16_t>(iBlockY);
int16_t iBlockZAsInt16 = static_cast<int16_t>(iBlockZ);
uint16_t uBlockXAsUint16 = reinterpret_cast<uint16_t&>(iBlockXAsInt16);
uint16_t uBlockYAsUint16 = reinterpret_cast<uint16_t&>(iBlockYAsInt16);
uint16_t uBlockZAsUint16 = reinterpret_cast<uint16_t&>(iBlockZAsInt16);
uint64_t uBlockXAsUint64 = static_cast<uint64_t>(uBlockXAsUint16);
uint64_t uBlockYAsUint64 = static_cast<uint64_t>(uBlockYAsUint16);
uint64_t uBlockZAsUint64 = static_cast<uint64_t>(uBlockZAsUint16);
uBlockXAsUint64 = uBlockXAsUint64 << 32;
uBlockYAsUint64 = uBlockYAsUint64 << 16;
// Bit-shifting of signed integer values has various issues with undefined or implementation-defined behaviour.
// Therefore we cast to unsigned to avoid these (we only care about the bit pattern anyway, not the actual value).
/*const ChunkKey uXPos = static_cast<ChunkKey>(iXPos);
const ChunkKey uXPos = static_cast<ChunkKey>(iXPos);
const ChunkKey uYPos = static_cast<ChunkKey>(iYPos);
const ChunkKey uZPos = static_cast<ChunkKey>(iZPos);
const ChunkKey xKey = ((uXPos >> m_uChunkSideLengthPower) & 0x3FF) << 20;
const ChunkKey yKey = ((uYPos >> m_uChunkSideLengthPower) & 0x3FF) << 10;
const ChunkKey zKey = ((uZPos >> m_uChunkSideLengthPower) & 0x3FF);*/
const ChunkKey zKey = ((uZPos >> m_uChunkSideLengthPower) & 0x3FF);
const ChunkKey key = 0xFFFF000000000000 | uBlockXAsUint64 | uBlockYAsUint64 | uBlockZAsUint64;
const ChunkKey key = 0x80000000 | xKey | yKey | zKey;
return key;
}