diff options
Diffstat (limited to 'src/mapgen.cpp')
| -rw-r--r-- | src/mapgen.cpp | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/src/mapgen.cpp b/src/mapgen.cpp index 041356e3d..32f7e29eb 100644 --- a/src/mapgen.cpp +++ b/src/mapgen.cpp @@ -89,11 +89,25 @@ Mapgen::Mapgen(int mapgenid, MapgenParams *params, EmergeManager *emerge) : { generating = false; id = mapgenid; - seed = (int)params->seed; water_level = params->water_level; flags = params->flags; csize = v3s16(1, 1, 1) * (params->chunksize * MAP_BLOCKSIZE); + /* + We are losing half our entropy by doing this, but it is necessary to + preserve reverse compatibility. If the top half of our current 64 bit + seeds ever starts getting used, existing worlds will break due to a + different hash outcome and no way to differentiate between versions. + + A solution could be to add a new bit to designate that the top half of + the seed value should be used, essentially a 1-bit version code, but + this would require increasing the total size of a seed to 9 bytes (yuck) + + It's probably okay if this never gets fixed. 4.2 billion possibilities + ought to be enough for anyone. + */ + seed = (s32)params->seed; + vm = NULL; ndef = emerge->ndef; biomegen = NULL; @@ -107,7 +121,7 @@ Mapgen::~Mapgen() } -u32 Mapgen::getBlockSeed(v3s16 p, int seed) +u32 Mapgen::getBlockSeed(v3s16 p, s32 seed) { return (u32)seed + p.Z * 38134234 + @@ -116,7 +130,7 @@ u32 Mapgen::getBlockSeed(v3s16 p, int seed) } -u32 Mapgen::getBlockSeed2(v3s16 p, int seed) +u32 Mapgen::getBlockSeed2(v3s16 p, s32 seed) { u32 n = 1619 * p.X + 31337 * p.Y + 52591 * p.Z + 1013 * seed; n = (n >> 13) ^ n; |