My friends and I were planning on starting a survival server for ourselves once 1.8 is officially released, and the possibility of having the nearest ice-based or mesa biome being 20 km away from 0,0 has become a bit of a concern. I understand that things like AMIDST and seed lists exist, but I'm looking for the actual algorithm that Minecraft uses so that I would be able to write a program which would, in some sense, automate seed-searching for particular patterns or features by generating just the biomes from random seeds.

As far as I understand, the biome patterns are entirely deterministic from the seed and are generated via some Perlin noise-based algorithm, but I can't seem to find any specific information anywhere on how the algorithm specifically works besides very high-level descriptions or explanations for outdated versions. However, I know something like this has already been done at least once since the Mindcrack server had its survival server reset semi-recently and specifically picked a seed with extremely varied biomes within a few kilometers of 0,0 due to distance limitations imposed by a worldborder.

In short, what are all the nitty-gritty details behind the algorithm which determines Minecraft's biomes, and how would I go about generating just the biomes from a seed if I intended to?


2 Answers 2


Your question is how to find a seed that fits a criteria?

If this is essentially your question then TheCodeRaider has already produced a brute-force script that will test a range of seeds against set criteria.


He was looking for sets of 4 witch huts within the spawnable sphere of a player. You're looking for criteria that are far more likely to be found, but to get that changed in his source code would require you to understand what he's written well enough to modify it.

If you can get that done, then this tool would be the closest possible starting point to solving your complicated problem.



I don't think anybody but Mojang knows that information. I assume that it is some sort of trade secret.

I think everybody else uses Amidst or a custom terrain generator to do what they want to do.

Go ahead and deobfuscate the code. You might get lucky. You might also be able to check the Mod Coder Pack. Also, the code/generator changes almost every version.

  • How do mods such as ExtrabiomesXL work then? surely they had to modify that code somehow? I'm not a programmer, so I'm not entirely sure. Aug 15, 2014 at 6:56
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    They can probably write their own classes. My thought is they add a new biome code to the "Generate These Biomes" list, and they just specify how to generate them in their own classfiles. I do not think that they can add specific biomes where they want.
    – Kaz Wolfe
    Aug 15, 2014 at 6:58
  • Ugh, this would be quite an undertaking with the advanced / new world gen features, no? Or are they applied more like 'post processing'? It's an interesting enough question, but unless Mojang chimes in, I think it's just (educated) guessing.
    – user43038
    Aug 15, 2014 at 7:52
  • @TimPost I think the actual GENERATION of content is post-processing based on the seed, but that the outline and the biomes are set at world creation.
    – Kaz Wolfe
    Aug 15, 2014 at 8:42
  • Much more importantly, how does AMIDST work in this case?
    – MrLemon
    Aug 15, 2014 at 11:06

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