MC-Chunker

Mc-Chunker is an application that uses a vanilla Minecraft Java Server to generate / pre-generate chunks in a configurable area.

Features

Generate any amount of chunks
Generate chunks in the Overworld, Nether or the End
(Optional) Limit the rate at which chunks are generated
(Optional) Works offline (user must provide mappings and launcher manifest as files)
(Optional) Save progress when stopping the server and resume on next run

Usage

Place the mc-chunker.jar in the directory of a Java Minecraft server (both jars must be in the directory). Start mc-chunker via a terminal/command line like:

java -jar mc-chunker.jar server.jar

The application will run and stop, prompting you to fill in the configuration. Edit the generated chunker.properties and start the application again. The application will run, start the Minecraft server, generate the configured chunks and it will stop, leaving the server running. You can interact with the server in the normal way.

To start mc-chunker you can start it the same way you are starting the Minecraft server. If you have a script or command like:

java -Xms4G -Xmx4G -jar server.jar nogui

You can modify it by inserting the name of the mc-chunker.jar like:

java -Xms4G -Xmx4G -jar mc-chunker.jar server.jar nogui

All JVM arguments will apply to the started server. All program arguments except the name of the server jar will be given to the Minecraft server.

Once you are done using mc-chunker you should remove it from your starting script. Continuing to use the server with mc-chunker is discouraged.

Works with "nogui" and with gui, however Chunker will output only in the console and not the gui

Configuration

To configure mc-chunker edit the chunker.properties file. Some of the values are:

x1, z1, x2 and z2 - these specify Chunk coordinates of two diagonal corners of a rectangular area to generate chunks in. These are inclusive
dimension - in which Minecraft dimension(s) to generate the chunks - possible values: OVERWORLD, NETHER or END. The default value is OVERWORLD. Comma separated list of values
stop - Whether to stop the Minecraft server when the chunk generation is done - possible values: true or false
suppress-server-output - If set to true, console output from the server will not be shown. Log output will remain the same. Possible values: true or false
max-generation-rate - Maximum number of chunks generated per second. Positive number
save-generation-progress - If set to true, when the server is shutdown if there are more chunks to be generated, current progress will be saved in a file and next time you start Chunker it will resume from where it left

Requirements

Java 8 or newer
A Minecraft vanilla server
Internet connection to retrieve Minecraft obfuscation mappings (planned to be optional)

Known issues

If the Minecraft server fails to start MC-Chunker will hang/crash. This includes the server not starting because you have not agreed to the EULA yet.
MC-Chunker is not compatible with older versions

Minecraft version compatability

Supports 1.14.4 and 19w36a through 1.16.4-pre1. Newer versions may work without modifications.

Planned features

Compatibility with more Minecraft versions. This may include older versions depending on how much work is required for compatibility, but there are no plans for compatibility with versions older than Snapshot 19w36a (the first to include obfuscation mappings; this is a snapshot for 1.15) and including 1.14.4
~~Option to stop server when chunk generation is done~~
~~Properly handle server not starting~~
~~Throttling of the generation speed~~
Ability to stop the server, save generation progress, start and resume the chunk generation from where it reached
~~Option to provide mappings as a file and enter the filename in chunker.properties~~
Option to use excessive amounts of CPU in order to speed up generation

How it works

Mc-chunker loads the server, makes a small modification (explained bellow) and starts the server, waits for the server to fully start and then starts telling the server to generate (and temporarily load) chunks, one at time. That is all.

The modification mc-chunker makes to the server is required in order to get a reference to a local variable from outside the scope. No (other) behaviour is changed. The server jar in the file system is not modified. When you are done using mc-chunker and start the server the normal way it will be 100% vanilla.

The rate at which chunks are generated is the rate at which Minecraft can generate them (unless there is a better way to do so than the one used). A reference speed is 20 chunks per second, but this will be affected by the speed of your system.

License

MC-Chunker is released under the Apache 2.0 license.

Copyright 2020 Ivan Zhivkov

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Disclaimer

Technically, running a Minecraft server with mc-chunker can be classified as a modded server, even if it behaves exactly like a vanilla server.

Minecraft content and materials are the intellectual property of their respective owners.

spiwn / mc-chunker