C++ console application to search for Minecraft Java Edition 1.4.2 - 1.6.2 seeds with Temples partially in swamp biomes
If you've played this game back when Witch mobs were added in 1.4.2 (12w38a) you maybe vaguely remember people reporting that witches spawn in Desert Pyramids or Jungle Temples. Well now I decided to investigate what was actually happening.
Note
Contributions to this repository are welcome. More about how to contribute on the development guide page.
After decompiling and deobfuscating source code with feather I found the root cause of this bug. Here is the summary:
-
Minecraft tried to place a "temple" structure in certain locations. Locations are randomly scattered around but deterministic for a given seed.
-
When game chooses a location is checks biome in the center of selected chunk (only one block) and chooses the structure type based on that:
DesertPyramidif the biome isBiome.DESERT, Biome.DESERT_HILLSJungleTempleif the biome isBiome.JUNGLE, Biome.JUNGLE_HILLSWitchHutif the biome isBiome.SWAMPLAND
-
No matter what type of temple was chosen, their bounding boxes get all assigned with witch spawning:
// Pseudocode public TempleStructure() { this.spawnEntries.add(new Biome.SpawnEntry( type: WitchEntity, weight: 1, minGroupSize: 1, maxGroupSize: 1 )); }
-
Next, during hostile mob spawning if spawn attempt happen to land within a bounding box of the temple it does the following check:
// Pseudocode public List getSpawnEntries(MobCategory category, int x, int y, int z) { Biome biome = world.getBiome(x, z); if (biome == null) { return null; } if (biome == Biome.SWAMPLAND && category == MobCategory.MONSTER && temple.isInside(x, y, z)) { return temple.getSpawnEntries(); }
-
The smartest of you probably figured out an issue here. Type of temple gets decided on a single block, yet spawning does not care about the type of the temple, it only cares that the spawning is happening inside of temple and in swamp biome. This means that it doesn't matter what type of temple got generated, all it's blocks that are located within swamp biome will spawn witches just like witch huts doo. Some more trivia:
// width, height, depth
static const PieceSize DESERT_PYRAMID = {21, 15, 21};
static const PieceSize JUNGLE_TEMPLE = {12, 10, 15};
static const PieceSize WITCH_HUT = {7, 5, 9};And it was fixed in Minecraft JE 1.6.3, a check was added that it is actually a witch hut.
// Pseudocode
public boolean isWitchHut(BlockPos pos) {
StructureStart structureStart = this.findStructure(pos);
if (structureStart == null || !(structureStart instanceof Start) || structureStart.pieces.isEmpty()) {
return false;
}
StructurePiece structurePiece = structureStart.pieces.get(0);
return structurePiece instanceof TemplePieces.WitchHut;
}And while in Minecraft JE 1.8.1 bounding box size of witch huts was actually increased by two blocks {7, 7, 9} allowing to build a farm with 3 floors, this is still not even close to jungle and desert pyramid sizes. So this is when my quest started, a quest to find seeds where instead of quad witch huts I search for desert pyramids that are mostly inside swamps.
My starting point was figuring out how game determines which biome it is at a given block. Thankfully I did not have to worry about implementing noise map fun myself, since I found cubiomes - C library that mimics the Minecraft biome generation. And supports old Minecraft JE versions!
Now all I had to do is to replicate logic that game uses to select chunks for temple generation. Thankfully that was just a couple of lines of code. From now on algorithm is simple:
Check center of the chunk biome to get temple type -> given it's type get it's bounding box size -> compute how many blocks are inside swamp
And thats basically it! Some optimizations and multithreading later - results are down below.
Tip
For previewing old Minecraft seeds I recommend using Amidst, Cubiomes Viewer or Minemap. And for even older versions you can use monolith-renderer or amidst-infdev.
Those seeds should work in every Minecraft JE version in range 1.4.2 - 1.6.2. In 1.6.4 it was silently fixed. The seed finder needs further optimizations, I only ran for ~100k seeds in single temple category and only scanned 65536x65536 area around 0, 0. As for multi-temples there must be a rewrite for sure to make it work.
| Seed | Structure type | X | Z | Witch spawn blocks | Total witch spawn blocks | % of max (21 * 21 - 1) * 5 * 4 |
|---|---|---|---|---|---|---|
| 3242038509290238342 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 423630031342907782 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 2056770643904541062 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 152903296189837702 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -6093007470444039802 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 6265716445114642822 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -7005265756839366266 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -5133452574688431738 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 3353602466647224710 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -7019026694616796794 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -3813559406086213242 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -4316228514255621754 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -9159567287464644218 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -5101538029921521274 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 6200810366761546118 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -7943307212948917882 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 5398339364371673478 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -4089054259312479866 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -1798128101014523514 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| -198785737156349562 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 3301690519790399878 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 | |||
| 1661819710655803782 | WitchHut | -144 | -160 | 126 | 2492 | 28.32% |
| DesertPyramid | -144 | 16 | 1580 | |||
| DesertPyramid | 0 | -160 | 660 | |||
| WitchHut | 16 | 0 | 126 |
| Seed | Structure type | X | Z | Swamp blocks | % of max 21 * 21 - 1 |
Spawning spaces |
|---|---|---|---|---|---|---|
| 28257 | DesertPyramid | 22784 | 16752 | 401 | 91.14% | 2005 |
| 1306145184061456995 | DesertPyramid | 15197824 | 18989808 | 399 | 90.68% | 1995 |
| 42162 | DesertPyramid | 49264 | -21248 | 393 | 89.32% | 1965 |
| 38711 | DesertPyramid | -29984 | -16752 | 381 | 86.59% | 1905 |
| 38513 | DesertPyramid | 46144 | 21616 | 375 | 85.23% | 1875 |
Note: this list may contain false positives, because of issue#1.
| Seed | Structure type | X | Z | Swamp blocks | % of max 12 * 15 - 1 |
Spawning spaces |
|---|---|---|---|---|---|---|
| 65631 | JungleTemple | -41200 | 21104 | 173 | 96.65% | 692 |
| 6156 | JungleTemple | -26608 | 9904 | 167 | 93.30% | 668 |
| 167 | JungleTemple | -56976 | -61376 | 167 | 93.30% | 668 |
| 3818 | JungleTemple | 7968 | 28016 | 165 | 92.18% | 660 |
| 62650 | JungleTemple | 65136 | -26256 | 165 | 92.18% | 660 |
| 1214 | JungleTemple | 21280 | 30304 | 164 | 91.62% | 656 |
| 2687 | JungleTemple | 23568 | -50608 | 164 | 91.62% | 656 |
| 2534 | JungleTemple | -14000 | -23232 | 163 | 91.06% | 652 |
| 3450 | JungleTemple | -24736 | 10832 | 163 | 91.06% | 652 |
| 62564 | JungleTemple | 53408 | 31792 | 163 | 91.06% | 652 |
| 470 | JungleTemple | -28496 | 30864 | 162 | 90.50% | 648 |
| 2516 | JungleTemple | -20688 | 8464 | 161 | 89.94% | 644 |
| 418 | JungleTemple | 8224 | 33312 | 161 | 89.94% | 644 |
| 135 | JungleTemple | 11328 | -34672 | 160 | 89.38% | 640 |
Since game checks center of the chunk to determine type of temple and witch hut doesn't extend far enough to cover that center piece, it is actually possible to find a witch hut that is fully outside of swamp, so I took a small side quest to find such witch hut.
| Seed | Structure type | X | Z | Swamp blocks | % of max 0 |
Spawning spaces |
|---|---|---|---|---|---|---|
| 903 | WitchHut | -65536 | 22384 | 0 | 100% | 0 |
The redstone block on this image shows location that was actually checked to determine type of temple and it is inside of swamp biome. Witch hut on the other hand is actually fully in river biome.
During research for this project I came across multiple posts with witch hut being generated on top of another witch hut:
Since those two posts had provided the seeds -753185017950826243 and -2274802501570798098 and tried to replicate that bud. I tried earliest version when witch huts were added as well as current latest version when posts were made and no success. Then when I tried to simply repopulate already existing witch huts with MCEdit and I managed to replicate those structures 1:1. So what is that, a rare bug where game populates same chunk twice? Or fake posts? As of right now I don't have definitive answer. However what is clear is that second population would move the witch hut bounding box up, only making a possible farm slower. You would not get x2 spawning spaces from it.
Minecraft actually uses only lower 48 bits of the seed for structure generation and full 64 bits for biomes. This means It is actually more effective to first find lower 48 bits where you get quad temple and later search through remaining sister seeds. I did not implement this logic yet, so contributions are welcome.
Note that this is completely opposite of shadow seeds - when two seeds share same biome map but everything else is different.
Tip
If you input seed 0 into seed field Minecraft would actually generate random one. To generate actual seed 0 world, as Panda explained his video "Seeds & Generation #01: Ways to Enter a Seed" you would need to enter something like PDFYFCD as suggested by seedinfo tool.
If you want to learn more about seed finding I recommend fnseedc repository.
I am currently working on a couple of designs: "Desert Pyramid Witch Farm and Extended Shifting Floor | Minecraft ~1.4.2 - 1.6.2":
- Clock-based
- Detection based with extended shifting floor
- Path finding-based
If you forgot how witch farming looked like in those days I also compiled a playlist "Witch Farm Tech".
Setup with VSCode
If you are using other IDE, you probably know that you are doing and able to compile C++ code yourself. Down below I will provide a simple setup.
This project includes the .vscode/extensions.json file, meaning that when you open project it will prompt you with "Do you want to install recommended extensions?" notification. Click yes.
Now click "Left Control + Shift + P" to open quick actions tab and search for "CMake: Configure". Then scan for kits and if there is none you would have to install some C++ compiler. After that is done you can compile this project for your system and run it.
To run different finders you can use Run and Debug tab on the left panel, there in the dropdown you can select different launch options. To modify launch options you can edit .vscode/launch.json file.
This program is licensed under the MIT License. Please read the License file to know about the usage terms and conditions.