Planet Minecraft

I've figured out something annoying. A game-generated world that is the result of not entering a seed cannot be reproduced.

I know that Minecraft uses the java.util.Random implementation of a generator. If it wasn't, then my earlier test of using strings that happened to have the same hash codes creating exactly the same world wouldn't have gone the way it did.

Java's implementation of a pseudo-random generator uses two constructors:

• Random() : uses system time as seed
• Random(long seed) : uses "seed" as the seed

and the system time is retrieved with:

• currentTimeMillis() : returns the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC as a long value.

The strings entered as seeds produce hash codes from -2,147,483,648 to 2,147,483,647.
As of right now, the current UNIX time in milliseconds is about 1,300,000,000,000.

So, unless the system time of your computer reverts back to some time in the first 25 days of 1970, you can't possibly have a time-seeded world that can be reproduced with an entered seed.

I kinda wanted to post some my older worlds' seeds because they are awesome, but it's impossible

That' really agitating. =\
I've punched in about 30-50 seeds and they all seem to be rolling mountains or sandy dunes and 1-3 lone massive mountains. Seems the more interesting hash codes are in the area of 100,000-9,999,999

[Zaralith]

You can find the seeds somewhere in the world data values. I think it is in the actual level.dat file, though I am not sure, because people were posting seeds long before it was a feature in the client. No idea where the seed is stored but i think it is stored somewhere so that the world generator can step toward a new area from the origin when it needs to if you are off in lala land, or it does voodoo and uses some random values that are set at the beginning and generates from a list of parameters. either way, no idea. If you have any old worlds that are still in the old chunks format, try looking at them.

cock : spawns you in a snowy wasteland beside an extremely large ice lake

[Zaralith]

For those following the research and discussion on minecraft seeds and terrain generation by myself and Hibbsi, Notch posted on the dev blog how basic terrain generation works, with more to come. http://notch.tumblr.com/

Funny...this is the first thread in the forums that caught my eye. And now it's also my first post.

I found it interesting as I've never even tried to create with seeds. So, of course, the first thing I do is create one with "gestankfaust" (stinkfist in German...sorta. It's a Tool song) and I get this crazy mix of archways, sand, and grass.

I spawned in and sand starts falling from the sky. Then I noticed, I was on top of a cavern or something because of all the mob sounds. Partially correct....a mob spawner.

Anyway. It's a really cool valley and stuff so I thought I'd share.

X=5
Z =75

(Spawner is at around Y:55 if I remember right)

gestankfaust:

Overall it was a pretty interesting pack. The falling sand happened right in front of me when I spawned, but it seemed to have a delay to it. (Damn near killed me)

Mojang-Awesome place in the hills.

[Zaralith]

So, I am not sure if this works with the current version of the game, but there is a program called MineSeeder that can supposedly extract the seed from a world that is already generated, though someone on the thread for it pointed out that the seed will only make the same world if the worlds are created during the same update, since the world generator is constantly being changed. Anyway, I am here supplying a link to it in case someone wanted to use it, since i think someone wanted to share a seed for a world that they received at random. Also, I think that the seeds given are the hash values that you obtain, not what needs to be entered, though I could be mistaken. Anyway, MineSeeder.

Very interesting, Zaralith. Yes, the hashcode is entirely dependent on what is generated, not what is actually typed in. There are many combinations of letters/numbers that represent the exact same hashcode and will generate the same world.

We studied this a while back in the thread, but we just couldn't pinpoint what each hashcode represented which was our biggest interest.

I'm also interesting in that if we have 2 identical hashcodes, will the world be the same at an extremely distant coordinate such as 1500,1500? I spent hours yesterday typing in random numbers and movie quotes and walked until night in one direction. It seemed each world had a very common theme depending on the hashcode given. This kind of gives the hint that if you have a code that has expansive deserts with brief forests and plains, that the rest of the world would be roughly the same, give or take an anomaly.

My studies could also be extremely flawed because I only ran in one direction (trying to make the X coordinate as negative as possible). It very well could be that the opposite direction would have been entirely different.

Edit:
I've messed with this extensively prior to being able to modify the seeds using the wildgrass mod. I tested each area and attempted to find which plant would grow in which biome. What was odd is that it took a very long time to find a specific plant in some worlds where it would be abundant in another.

try matthias18

Interesting and cool part about this, is that I took an old save of mine, which was just after beta, and used the seed it showed within the mod/app listed above. The save was relatively untouched, as I'm including it in my next project, but had buildings I wasn't satisfied with. The seed/hash worked like a reset button.

MineSeeder FTW!!

i had 1 time ther spawned sinki hole,,,
it was loopkilling not nice