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Revert binary database block position encoding

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This reverts commits a2003b0d55 and 54ffe2e5de.

These weren't correct.  Add a black magic warning instead.
This commit is contained in:
ShadowNinja 2014-04-22 12:52:48 -04:00
parent 9ec281c712
commit 41bc24477b
2 changed files with 31 additions and 10 deletions
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39
src/database.cpp
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@ -20,6 +20,14 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "database.h"
#include "irrlichttypes.h"
/****************
* Black magic! *
****************
* The position hashing is very messed up.
* It's a lot more complicated than it looks.
*/
static inline s16 unsigned_to_signed(u16 i, u16 max_positive)
{
if (i < max_positive) {
@ -30,19 +38,32 @@ static inline s16 unsigned_to_signed(u16 i, u16 max_positive)
}
// Modulo of a negative number does not work consistently in C
static inline s64 pythonmodulo(s64 i, s16 mod)
{
if (i >= 0) {
return i % mod;
}
return mod - ((-i) % mod);
}
s64 Database::getBlockAsInteger(const v3s16 pos) const
{
return (((u64) pos.Z) << 24) +
(((u64) pos.Y) << 12) +
((u64) pos.X);
return (u64) pos.Z * 0x1000000 +
(u64) pos.Y * 0x1000 +
(u64) pos.X;
}
v3s16 Database::getIntegerAsBlock(const s64 i) const
v3s16 Database::getIntegerAsBlock(s64 i) const
{
v3s16 pos;
pos.Z = unsigned_to_signed((i >> 24) & 0xFFF, 0x1000 / 2);
pos.Y = unsigned_to_signed((i >> 12) & 0xFFF, 0x1000 / 2);
pos.X = unsigned_to_signed((i ) & 0xFFF, 0x1000 / 2);
return pos;
v3s16 pos;
pos.X = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
i = (i - pos.X) / 4096;
pos.Y = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
i = (i - pos.Y) / 4096;
pos.Z = unsigned_to_signed(pythonmodulo(i, 4096), 2048);
return pos;
}