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Just How big is "infinity" [in minetest]?

PostPosted: Thu Jun 27, 2013 17:30
by BadWolf
Hey I was trying to find a FAQ and I searched the forum, but it seems that no one has brought up this before... Currently I'm on a mission, exploring the cave patterns by digging essentially straight down. And I got curious: When will I reach the bottom, is there a bottom?

On the official info it says "nearly infinite." What does this mean? Since true infinity is beyond the scope of computing power, how does that function?

PostPosted: Thu Jun 27, 2013 17:50
by Dan Duncombe
I think a full size map is around 31000 nodes in each direction from 0, 0, 0. A full size uncompressed map file is around 200 terabytes at least.

PostPosted: Thu Jun 27, 2013 17:55
by Menche
The world goes from -30912 to +30927 in all 3 directions.

PostPosted: Thu Jun 27, 2013 18:07
by BadWolf
wow... 200 terabytes? What's it compressed?

PostPosted: Thu Jun 27, 2013 18:11
by Dan Duncombe
A compressed full size map may be around 100 terabytes if you use normal zipped file (like in Windows) I think. You may get as low as 20 terabytes if you are lucky.

PostPosted: Thu Jun 27, 2013 18:19
by BadWolf
So I guess that leads me to this obvious deduction. Does it then randomly generate around you as you reach the limit?

PostPosted: Thu Jun 27, 2013 18:41
by Dan Duncombe
No idea... I thought it overwrote whatever was at the opposite end of the map, but I couldn't be sure...

PostPosted: Thu Jun 27, 2013 19:30
by VanessaE
Neither, for mapgen v6, the map simply stops generating at the edges. You can even fly out past the edges and see the hollowed-out blocks under the surface.

I think with the next generation map generator being worked on, there are super-tall mountains at the edges.

PostPosted: Thu Jun 27, 2013 19:48
by onpon4
Is there something requiring Minetest to impose a limit, or making it difficult for it to not do so?

PostPosted: Thu Jun 27, 2013 22:23
by Menche
I think that it is limited by the size of a short integer used for positions. If so, you should be able to use a bigger datatype to get a bigger map.

PostPosted: Fri Jun 28, 2013 00:10
by paramat
"Nearly infinite" haha.

PostPosted: Fri Jun 28, 2013 01:13
by VanessaE
It's defined both by the size of the variables used to track your position and by the horrible rendering glitches that happen way out near the edges of the map. I've read of ways the latter can be fixed (basically, make the engine not abuse the method Irrlicht uses for handling map information), but no idea if such things can actually be applied to Minetest at this point.

PostPosted: Fri Jun 28, 2013 06:44
by Jordach
Menche wrote:I think that it is limited by the size of a short integer used for positions. If so, you should be able to use a bigger datatype to get a bigger map.
I already suggested long long int, but that breaks compatibility.

But then it has the issue of not being a float. Honestly, fuck C++

PostPosted: Fri Jun 28, 2013 09:57
by Thermal_Shock
paramat wrote:"Nearly infinite" haha.

That nearly infinite claim on the main page of the site has always bugged me.

PostPosted: Fri Jun 28, 2013 12:54
by paramat
Keep digging the bottom's at y = -infinity + 1

PostPosted: Sat Jun 29, 2013 00:15
by darkskyabove
Rather than start a new thread, this seems the ideal place to pose a map-size question.

If I roam to one corner of the map (say, north-west) and then follow the edge all the way around, back to starting point, is the generated terrain then saved, or might it be different upon returning? Obviously, I'm not willing to dedicate 100 TB to save a map. My guess is that the terrain does not have to be explicitly saved, as the generation algorithm should reproduce the same terrain, with only the changes saved.

The point of my inquiry is that, upon considering the start of a server, I have an idea to spend the time roaming the entire map and placing surprises!, some negative, but mostly caches of materials, (wouldn't you just love to find a cache!!!), and a few environmental effects, before opening the map to players. If the entire file needs to be saved, that pretty much squashes my idea.

PostPosted: Sat Jun 29, 2013 00:59
by kaeza
darkskyabove wrote:Rather than start a new thread, this seems the ideal place to pose a map-size question.

If I roam to one corner of the map (say, north-west) and then follow the edge all the way around, back to starting point, is the generated terrain then saved, or might it be different upon returning? Obviously, I'm not willing to dedicate 100 TB to save a map. My guess is that the terrain does not have to be explicitly saved, as the generation algorithm should reproduce the same terrain, with only the changes saved.

The point of my inquiry is that, upon considering the start of a server, I have an idea to spend the time roaming the entire map and placing surprises!, some negative, but mostly caches of materials, (wouldn't you just love to find a cache!!!), and a few environmental effects, before opening the map to players. If the entire file needs to be saved, that pretty much squashes my idea.

Saving only map diffs has been discussed before, and is a great idea. It's just that nobody had the time (or inspiration) to code it yet.

As for placing stuff manually in the map, that's a bad idea. A better approach is creating a mod that programatically places chests with some stuff based on some factors.

PostPosted: Sat Jun 29, 2013 01:57
by ch98
60000^3 block is enough to have a never ending game. There is enough resources for peoples to play years if you generate the whole map.

PostPosted: Sat Jun 29, 2013 02:03
by darkskyabove
@kaeza: Good advice on the placing. I have been debating the pros and cons of interfering with the overall randomness. Thanks.

PostPosted: Sat Jun 29, 2013 11:03
by PilzAdam
darkskyabove wrote:Rather than start a new thread, this seems the ideal place to pose a map-size question.

If I roam to one corner of the map (say, north-west) and then follow the edge all the way around, back to starting point, is the generated terrain then saved, or might it be different upon returning? Obviously, I'm not willing to dedicate 100 TB to save a map. My guess is that the terrain does not have to be explicitly saved, as the generation algorithm should reproduce the same terrain, with only the changes saved.

The point of my inquiry is that, upon considering the start of a server, I have an idea to spend the time roaming the entire map and placing surprises!, some negative, but mostly caches of materials, (wouldn't you just love to find a cache!!!), and a few environmental effects, before opening the map to players. If the entire file needs to be saved, that pretty much squashes my idea.

Its almost impossible for you to do that all over the map (the world is just too big). You should wrirte a mod that places these things.

PostPosted: Sat Jun 29, 2013 12:35
by kaeza
PilzAdam wrote:Its almost impossible for you to do that all over the map (the world is just too big). You should wrirte a mod that places these things.

Have you read the other posts?

PostPosted: Sun Jun 30, 2013 09:38
by Cooper97
My PC has only 2 GB RAM Memory. It may crash the server if the map is to big. Is there any way to limit the mapsize to 1000^3?

PostPosted: Sun Jun 30, 2013 10:26
by Calinou
Cooper97 wrote:My PC has only 2 GB RAM Memory. It may crash the server if the map is to big. Is there any way to limit the mapsize to 1000^3?


Parts of the map that are not loaded or generated are not into RAM. Parts of the map where you already went to will be unloaded after a restart, or 10 minutes by default.

You can use mods that generate unbreakable walls that kill instantly to limit map size. :P

PostPosted: Tue Sep 24, 2013 16:58
by JackGruff
paramat wrote:Keep digging the bottom's at y = -infinity + 1


I think you meant -infinity - 1

Not that that means anything either ;)

PostPosted: Tue Sep 24, 2013 18:56
by paramat
:) -infinity+1 is nearly infinite in the negative direction.
-infinity-1 is beyond infinity :)