MC map-size reduction tool?

[M!C]

When Facefoiled mentioned his long up- and download times for maintaining Edolas I came up with a little idea that could make things a bit easier.

I would love to see a program of sorts that detects which chunks in a MC map differ from the seed (have been altered by the player) and deletes the rest (every unaltered chunk).

This should, depending on your exploration habits, reduce the filesize quite drastically (I know that for me it'd be more than 50%).

Sadly I'm not good enough at programming yet to do it myself, so I'm hoping someone here might take on this challenge (if it even is one).

[SilvasRuin]

And how would that effect/be effected by slain and wandered animals? Creeper explosions would be more frustrating than usual as well.

[Stormweaver]

Not to mention endermen, and sand/gravel that falls after generating unsupported.

[Zhil]

Hmm, interesting idea, but not very plausible due to the issues mentioned

[M!C]

Thanks for the input guys. You made me aware that this is probably a bit more complex then I at first thought (though I intentionally kept the OP short to add in more details later and not hit you with a wall of text already in the first post).

I still believe there is some potential in this idea so I'll try and name solutions for the problems you mention.

If I assume something here that is simply wrong please tell me. I can't help it since I have close to no inside in MC code (or the way worlds are stored for that matter).

And how would that effect/be effected by slain and wandered animals? Creeper explosions would be more frustrating than usual as well.

About animals and other entities:

Afaik mobs are not part of the seed anyway so they wouldn't be considered while checking chunks for changes.

As for tile entities (those are assigned to blocks with inventories etc., right?) :
Any chunk containing a chest or similar should be kept in the map since they are either player placed or occur rarely in dungeons (where you don't want to find loot twice).
This also applies for any blocks that are not part of mapgeneration (that would cover most/many modblocks).

Not to mention endermen, and sand/gravel that falls after generating unsupported.

Now for Creepers, Endermen, gravel, sand and the occasional tree felled on expeditions:

There are two ways I'd like to see combined for handling this.

First thing is I would suggest excluding certain blocks from the change detection. Most certainly among those are leaves, long gras, flowers and other plants. Maybe it could be optional to also include wood, dirt, gravel, sand and water.
This way the user can decide wether he wants to keep even the smallest change in the map or wants to go for more efficient filesize reduction.


The other available option should be to categorize the amount of change in a chunk and therefore decide which to keep as they were.

Example (I'm just throwing in some numbers here):
> 20 changes: chunk and surrounding chunks are kept
10-20 changes: chunk is kept
<10 changes: chunk might be deleted

Keep in mind that both the number of changes and the blocks in question have to be considered before deleting a chunk.

[Deepsniper]

The only blocks you would really need to check for are ores and player built blocks that don't appear in the "wild" that way it can be relatively simple to check if these chunks are player modified or natural. mix that with the amount of changes in each chunk and your set...

[SilvasRuin]

After the breeding changes, the animals did indeed become tied to the seeds. When a chunk is first loaded, it checks to see what passive mobs should spawn there, if any, and does so. Later random spawns aren't tied to the seed, but the guaranteed passive mobs you get are. If you don't believe me, try it. Create several creative worlds, all on the same seed, and keep track of what animals you find where.

The most trouble that would come from the interaction with animals is someone walling off a chunk full of cows that they want to protect and then abusing this feature to get unlimited cows without breeding.