[1.12.2] Custom IChunkLoader

[the4naves 0]

So long story short, I need to be able to return any chunk I want when the game requests to load a chunk (Ex: Game requests chunk at (5, -3), I return the chunk at say, (2, 7), then display that chunk at (5, -3)).

Looking through the source code, it seems the way to do this would be to utilize a custom IChunkLoader, and/or IChunkProvider (NOTE: I do NOT mean IChunkGenerator. From what I understand, the chunk generator used to be called the chunk provider, but that serves a completely different purpose now), however there doesn't seem to be any way to access instances of these classes (Or at least the classes that implement them) other than reflection and a custom WorldProvider in a custom dimension, as all fields I could find were private or protected.

So before I go along with my reflection route, is there an easier/intended way of doing this, and are the classes I've found even the correct ones?

I've done a fair amount of research, but no one seems to have an answer.

Edited June 18, 2019 by the4naves
Ease of Reading

[diesieben07 6931]

Do you want the chunks to actually be mirrors of each other? i.e. if player places a block in one, it's also placed in another?

[the4naves 0]

In essence, yes, though the approach I'm going for is more simply overriding, for example, the loadChunk() method in IChunkLoader. (Or similer)

So in other words, I'd like to "trick" the game into thinking the Chunks I give it when it requests them are the actual world.

For placing blocks, maybe sounds and mob AI, those will probably need more overrides, most likely overriding the methods to get a block in the world, along others, but I can address those later.

In the best case scenario I would just like to be able to provide my own subclasses to be used instead of the vanilla ones.

Edited June 18, 2019 by the4naves
Extra info

[diesieben07 6931]

First, some terminology:

• IChunkGenerator: Generates new chunks, implementations exist for overworld, nether, etc.
• IChunkLoader: Loads existing chunks from disk, only implementation is AnvilChunkLoader and it's expected to be the only one in many places.
• IChunkProvider: Basically manages a world's chunks in memory. Will use IChunkLoader to load existing ones from disk and IChunkGenerator to generate new ones.

I still think it's a bad idea to have the same Chunk object at two different places. Firstly, because Chunk has built in x and z coordinates and also because Chunks hold TileEntities, which store their absolute block coordinates (not chunk relative).

What you need to do is either have a very custom Chunk implementation which mirrors some other chunk or give up on mirroring and just return a copy at the time of request.

[the4naves 0]

To your first point, I do mostly agree, I think having the same Chunk loaded in multiple places at the same time could cause all kinds of problems, but what I'm planning on doing shouldn't ever create a situation like that.

To give some context, I'm trying to create a "world wrap" effect, where the world loops infinitely in a specific direction (Generation can be handled by tile-able noise). To do this, there will be an invisible "border" that will teleport you to the other side when you touch it. To prevent the game from having to suddenly load a bunch of chunks and to prevent structures you've build from suddenly popping in, as you approach the border, the game should load chunks on the other side, and provide them to the chunk provider in lieu of what is actually near you.

So I suppose a custom chunk could simply mirror the chunks it needs to, but a custom chunk loader/maybe a provider seems cleaner and might be better for performance.

[diesieben07 6931]

And then someone places a chunkloader somewhere and your assumption breaks.

Or, even simpler, there are two people on the server.

[the4naves 0]

But wouldn't you get that anyway in vanilla with two players, or a player and a chunk loader in the same area?

[diesieben07 6931]

4 minutes ago, the4naves said:

But wouldn't you get that anyway in vanilla with two players, or a player and a chunk loader in the same area?

Yes. But vanilla does not try to load the same chunk in two places.

[the4naves 0]

Ok, so I've looked into the source code a bit more, and it looks like everything I'm trying to do could be accomplished by overriding the WorldClient and by the looks of it WorldServer classes. (Subclasses of World)

The Minecraft class keeps a public instance of WorldClient (Yay no reflection), and it seems to only be set in loadWorld(). Forge seems to have the job of loading worlds, and when doing so calls launchIntegratedServer(), which starts the server. I'm not sure overriding WorldServer is required though.

Is there a forge event or something similar that fires on world load I could hook into to replace the world with my own subclass? (The subclass would copy over the info from the existing one if needed)

Thanks for your help.