MCA Selector

An external tool to export or delete selected chunks and regions from a world save of Minecraft Java Edition.

• Usage
  • Video Tutorials
  • Navigation
  • Selections
  • Chunk filter
  • NBT Changer
  • Chunk Editor
  • Chunk import
  • Copy and Paste
  • Swapping chunks
  • Caching
  • Generating an image
  • Debugging
• Supported Versions
• Headless mode
  • Mandatory and optional parameters
    • Create selection
    • Export chunks
    • Import chunks
    • Delete chunks
    • Change NBT
    • Cache images
    • Generate image from selection
    • Configuration parameters
  • Filter query
  • Change values
• Checkout and building
• Translation
• Download and installation
  • What works on most systems
  • If you have Minecraft Java Edition installed
  • If you receive a JavaFX error

Usage

Video Tutorials

For people who prefer watching a video to understand how the MCA Selector works, there some very good tutorials on Youtube explaining the basics:

• How To Reset Chunks In Your Minecraft World! by Farzy
• How To Clear Unwanted Chunks In Minecraft 1.16 | MCASelector Tutorial by Muriako
• Preparing Your World for the Nether Update! - The Minecraft Survival Guide starting at 2:52 by Pixlriffs
• How To Reset The End Dimension! - The Minecraft Survival Guide starting at 8:45 by Pixlriffs

Navigation

Executing the tool, it shows an empty window with a chunk and a region grid. To actually show a world, open a folder containing Minecraft Anvil (*.mca) files. The tool will then render a top-down view of this world that you can zoom into and zoom out of by scrolling up and down and that you can move around using the middle mouse button (Cmd+LMB on Mac OS) or using WASD.

Zooming out far enough disables the selection of single chunks but lets you select entire regions.

Selections

Upon finishing selecting chunks and regions, they can be deleted or exported using the Selection-menu. Exported chunks and regions are not deleted from the original world.

A selection (not the chunks and regions themselves) can also be exported or imported and even be applied to different worlds.

Chunk filter

The MCA Selector also contains a powerful tool to delete or export chunks and regions by conditions like the data version, the time it was last updated, how much time players have spent in this chunk and some more. Multiple of these conditions can be used to create a very specific query describing what chunks and regions should be deleted or exported.

Because the conditions use internal values used by Minecraft, the following table gives a brief explanation on what they do:

Fields that allow multiple comma separated values act the same as multiple consecutive filters of the same type with single values connected with the AND operator.

A string representation of the query is printed in a text field below the query editor. When entering a query into this field directly, press Enter to parse it into the query editor.

Notice Running the query will check the .mca-file's name first if the query would even apply to any chunk in this file using the xPos and zPos conditions, as long as the query is built in a way that allows doing this.

NBT Changer

The NBT Changer modifies the world files directly by changing specific values.

You can change the following values:

Once the field is highlighted in green, the value is considered valid and will be changed. A gray field, no matter its content, will be ignored.

A string representation of the to be changed fields is printed in a text field below the editor. When entering a field string into this field directly, press Enter to parse it into the editor.

For more information about the fields have a look at the chunk format description on Minecraft Wiki

Chunk Editor

When selecting a single chunk, the menu "Edit chunks" becomes available. It allows precise editing of the entire NBT structure of that chunk, including poi and entities data. Names and values can be changed, added, deleted or moved (via drag & drop).

Notice When the NBT editor does not show any data, the cached top-down view might be outdated, and the chunk might not exist anymore in the mca files. In that case, clearing the cache will re-render the regions from scratch and show the up-to-date top-down view.

Chunk import

Importing chunks can be easily done by opening the target world first using File --> Open and then merging the chunks of a second world using Tools --> Import chunks. After selecting a folder containing region files, it is possible to import the chunks with a bunch of additional options.

Options:

• Offset imports chunks with an offset in chunk coordinates. To convert block coordinates to chunk coordinates, divide them by 16.
• Overwrite existing chunks deletes existing chunks and overwrites them with the imported ones.
• Apply to selection only imports chunks into the current selection.
• Sections defines one, or a range of sections to be imported. A range has the format <from>:<to>, inclusive. Omitting <from> sets the lowest possible value, omitting <to> sets the highest possible value. :, true or empty means all sections. Multiple ranges or single indices can be defined by separating them with a comma. If a chunk does not already exist at the location, it will be created containing only the specified sections of the imported chunk.

Notice Commands inside of command blocks will not be changed. Maps will not be updated, because their data is not stored inside region files.

Copy and Paste

It is possible to copy a selection to the system clipboard and pasting it to a different location in the same world or into an entirely different world. After making a selection, use Selection --> Copy chunks or press Ctrl+C (Cmd+C on Mac). After navigating to the location in the world where the copied chunks need to be pasted, use Selection --> Paste chunks or press Ctrl+V (Cmd+Von Mac) to display an overlay showing where the clipboard will be imported to. The overlay can be moved around by pressing and holding the left mouse button. Press Ctrl+V again to import the chunks at the selected location. This will open the Import chunks dialog with prefilled values depending on where the overlay has been placed. Copying can be cancelled by pressing Esc.

Swapping chunks

When exactly two chunks are selected, they can be swapped using Tools --> Swap chunks. This is useful for corrupted region files when Minecraft failed to correctly save the region file index, resulting in scrambled chunks.

Caching

The tool creates an image for each region from the provided mca-files. These images are saved separately inside the respective operating system's specific cache folders. Experience showed that a Minecraft world with a size of 10GB resulted in cached image files with a total size of 80-100MB. Caching as many regions as possible significantly improves loading times.

• Windows: %LOCALAPPDATA%\mcaselector\cache if %LOCALAPPDATA% is set, otherwise <parent directory of mcaselector.jar>\mcaselector\cache
• MacOS: ~/Library/Caches/mcaselector
• Linux: $XDG_CACHE_HOME/mcaselector if $XDG_CACHE_HOME is set or the first directory that contains a folder mcaselector in $XDG_CACHE_DIRS or a new directory called mcaselector in the first entry in $XDG_CACHE_DIRS is created or if neither $XDG_CACHE_HOME nor $XDG_CACHE_DIRS is set ~/.cache/mcaselector.

Generating an image

MCA Selector is capable of generating an image based on a selection.

Debugging

If something is not working properly or if you want to see what exactly the MCA Selector is doing, debugging can be enabled in the settings. Informative messages and errors will be printed to the console as well as to a log file. The log file is stored in the following directory and is overwritten after each new start of the program:

• Windows: %LOCALAPPDATA%\mcaselector\debug.log if %LOCALAPPDATA% is set, otherwise <parent directory of mcaselector.jar>\mcaselector\debug.log
• MacOS: ~/Library/Logs/mcaselector/debug.log
• Linux: $XDG_DATA_HOME/mcaselector/debug.log if $XDG_DATA_HOME is set or the first directory that contains a file mcaselector/debug.log in $XDG_DATA_DIRS or mcaselector in the first entry in $XDG_DATA_DIRS or if neither $XDG_DATA_HOME nor $XDG_DATA_DIRS is set ~/.local/share/mcaselector/debug.log.

Alternatively, the location of the log file can be viewed by clicking on the link in the settings dialog.

Supported Versions

The MCA Selector currently supports the following Minecraft versions:

There is no guarantee for worlds generated in a Snapshot version to work, even if it is specified in the table above. This only represents the current development status towards the next Minecraft release. Old Snapshots of past Minecraft releases are not supported.

Headless mode

MCA Selector can be run in a headless mode without showing the UI. Using any command line parameter automatically switches to headless mode. A cheat-sheet with all commands can be found here.

Mandatory and optional parameters

Create selection

Export chunks

Import chunks

Delete chunks

Change NBT

Cache images

Notice This requires a working JavaFX installation.

Generate image from selection

Notice This requires a working JavaFX installation

Configuration parameters

Filter query

A filter query is a text representation of the chunk filter that can be created in the UI of the program. It is shown in the text field below the query editor of the Chunk filter tool. Example:

--query "xPos >= 10 AND xPos <= 20 AND Palette contains \"sand,water\""

This will select all chunks that contain sand and water blocks and their x-position ranges from 10 to 20. As shown, double quotes (") must be escaped with a backslash.

Groups are represented with a pair of parentheses ((...)). As with the chunk filter, logical operators are evaluated from left to right, and AND has a higher precedence than OR. In other words, a AND b OR c AND d AND e is the same as (a AND b) OR (c AND d AND e). It differs from c AND d AND e OR a AND b not by the result, but by the sequence of tests performed due to short-circuiting.

Change values

The query for changing NBT values in chunks looks slightly different to the filter query. It is a comma (,) separated list of assignments. Example:

--filter "LightPopulated = 1, Status = empty"

This will set the field "LightPopulated" to "1" and "Status" to "empty". Just like the filter query, the query to change values is printed to the console when using the UI in debug mode.

Checkout and building

To checkout master:

git clone https://github.com/Querz/mcaselector.git

To build a standalone jar file on Mac OS or Linux using the Gradle Wrapper, run

./gradlew build

On Windows, run

gradlew.bat build

The resulting jar files can be found in build/libs/.

Translation

The UI language of the MCA Selector can be dynamically changed in the settings. The following languages are available:

• English (UK)
• German (Germany)
• Chinese (China) (thanks to @LovesAsuna for translating)
• Chinese (Taiwan) (thanks to @hugoalh for translating)
• Czech (Czech Republic) (thanks to @mkyral for translating)
• Spanish (Spain) (thanks to @NathanielFreeman for translating)
• Portuguese (Brazil) (thanks to @cr1st0ph3r for translating)
• Portuguese (Portugal) (thanks to @D3W10 for translating)
• French (France) (thanks to @SkytAsul and @DoctaEnkoda for translating)
• Swedish (Sweden) (thanks to @TechnicProblem for translating)
• Russian (Russia) (thanks to @Quarktal for translating)
• Dutch (Netherlands) (thanks to @Clijmart for translating)
• Italian (Italy) (thanks to @valeilsimpaticone for translating)
• Polish (Poland) (thanks to @Marcinolak for thranslating)

If you would like to contribute a translation, you can find the language files in resources/lang/. The files are automatically detected and shown as the respective language option in the settings dropdown menu once they are placed in this folder.

Download and installation

MCA Selector modifies and deletes chunks in your Minecraft world. Please make backups of your world before using.

Download Version 1.14.2 (Windows Installer)

"Requirements":

• Windows 7-10 64bit
• At least 6 GB of RAM

Download Version 1.14.2 (Universal)

"Requirements":

• Either:
  • 64bit JRE 8+, you can get it from HERE
  • A Minecraft Java Edition installation
• A computer
  • At least 6 GB of RAM. If lower, more RAM has to manually be assigned to the JVM using the -Xmx argument. Assigning 4 GB is recommended.
• A brain

What works on most systems

Most likely, .jar files are associated with java on your computer, it should therefore launch by simply double clicking the file (or however your OS is configured to open files using your mouse or keyboard). If not, you can try java -jar mcaselector-1.14.2.jar from your console. If this doesn't work, you might want to look into how to modify the PATH variable on your system to tell your system that java is an executable program.

If you have Minecraft Java Edition installed

Minecraft Java Edition comes with a JRE that you can use to start the MCA Selector, so there is no need to install another version of Java on your system.

For Windows:

• Hold Shift and Right-click on an empty space and select Open PowerShell window here (Open Command window here on Windows 8 and earlier).
• Type & "C:\Program Files (x86)\Minecraft\runtime\jre-x64\bin\java" -jar, then drag and drop the mcaselector-1.14.2.jar into the console and press Enter. In the Command window (Windows 8 and earlier), the command starts with "C:\Program Files (x86)\Minecraft\runtime\jre-x64\bin\java" -jar instead and the path to mcaselector-1.14.2.jar must be typed or copied and pasted into the console manually.

For MacOS:

• Press Cmd+Space, type Terminal and press Enter.
• Type ~/Library/Application\ Support/minecraft/runtime/jre-x64/jre.bundle/Contents/Home/bin/java -jar (with a space at the end), then drag and drop the mcaselector-1.14.2.jar into the console and press Enter.

WARNING: For MacOS 10.14+ (Mojave) It is NOT recommended to use the JRE provided by Minecraft (1.8.0_74), because it contains a severe bug that causes JavaFX applications to crash when they lose focus while a dialog window (such as the save-file-dialog) is open (see the bug report here). This bug has been fixed in Java 1.8.0_201 and above.

If you receive a JavaFX error

"When I run mcaselector-1.14.2.jar, an error dialog appears that looks like this:"

Open the console or terminal on your OS.

For Windows:

• Hold Shift and Right-click on an empty space on your desktop and select Open PowerShell here (Open Command window here on Windows 8 and earlier).

For MacOS:

• Press Cmd+Space, type Terminal and press Enter.

Type the command java -version and press Enter. If the output shows that your java command is linked to java version "1.8.0", you can simply run MCA Selector through the console.

For Windows and MacOS:

• Type java -jar (with a space at the end) and drag and drop the mcaselector-1.14.2.jar into the console and hit Enter.

For Linux:

• Run java -jar <path to mcaselector-1.14.2.jar where you replace everything in <>.

If the output shows a Java version higher than Java 8, please find and download the appropriate JavaFX version from Here. If you know what to do, do it. If you don't, follow these steps:

For Windows:

• Download "JavaFX Windows SDK" for your Java version from here.
• Unzip the .zip-file with your program of choice, then navigate into the unzipped folder.
• Hold Shift and Right-click on an empty space in that folder and select Open PowerShell window here (Open Command window here on Windows 8 and earlier). Type java --module-path (with a space at the end), then drag and drop the lib-folder into the console. Continue to type --add-modules ALL-MODULE-PATH -jar (with a space at the beginning and the end), then drag and drop the mcaselector-1.14.2.jar into the console and hit Enter.

For MacOS:

• Download "JavaFX Mac OS X SDK" for your Java version from here.
• Double-click the .zip-file to unpack, then navigate into the unzipped folder.
• Press Cmd+Space, type Terminal and press Enter. Type java --module-path (with a space at the end), then drag and drop the lib-folder into the console. Continue to type --add-modules ALL-MODULE-PATH -jar (with a space at the end), then drag and drop the mcaselector-1.14.2.jar into the console and hit Enter.

For Linux:

• Download "JavaFX Linux SDK" for your Java version from here.
• Unzip the .zip-file with your program of choice.
• Open the command prompt and run java --module-path <path to unzipped folder>/lib --add-modules ALL-MODULE-PATH -jar <path to mcaselector-1.14.2.jar> where you replace everything in <> with the appropriate paths.
• Some distributions like AdoptOpenJDK (shipped with most Linux distributions) do not ship with JavaFX by default. On Debian, an open version of JavaFX is contained in the openjfx package. This or some other installation of JavaFX is required to run the mcaselector-1.14.2.jar.

To avoid having to go through this process every time to start MCA Selector, the resulting command can be copied into a .bat-file on Windows or .sh-file on MacOS and Linux and can then be executed by double-clicking the .bat-file on Windows or running sh <file>.sh in the terminal / console on MacOS or Linux where <file> must be replaced by the name of the .sh-file.

If none of these instructions work, apply "A brain" that you providently held ready after having read the "Requirements" section carefully. Or ask your question on Discord.