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MCA Selector

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



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:

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.

MCA Selector window showing chunk and region grid

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.

MCA Selector window showing chunk and region selection export

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.

MCA Selector window showing the chunk filter

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

Condition Type Description
Group - Groups multiple conditions.
Not Group - A negated group.
DataVersion int The DataVersion tag of the chunk. 100-1343 for 1.12.2 and below, 1444 for 1.13 snapshots and above.
InhabitedTime long The total amount of time in game-ticks players have spent in that chunk. 1 second is ~20 ticks. Also accepts a duration string such as 1 year 2 months 3 days 4 hours 5 minutes 6 seconds.
Timestamp int The time a chunk was last saved in epoch seconds. Also accepts a timestamp in the yyyy-MM-dd HH-mm-ss-format such as 2018-01-02 15:03:04. If the time is omitted, it will default to 00:00:00.
LastUpdate long The time a chunk was last saved in ticks since world creation. 1 second is ~20 ticks. Also accepts a duration string such as 1 year 2 months 3 days 4 hours 5 minutes 6 seconds.
xPos int The location of the chunk on the x-axis in chunk coordinates.
zPos int The location of the chunk on the z-axis in chunk coordinates.
Palette String A list of comma (,) separated 1.13 block names. The block names will be converted to block ids for chunks with DataVersion 1343 or below. The validation of block names can be skipped by writing them in single quotes ('). Example: sand,'new_block',gravel.
Status String The status of the chunk generation. Only recognized by Minecraft 1.13+ (DataVersion 1444+)
LightPopulated byte Whether the light levels for the chunk have been calculated. If this is set to 0, converting a world from 1.12.x to 1.13 will omit that chunk. Allowed values are 0 and 1.
Biome String/int One or multiple biome names and IDs, separated by comma (,). For a reference of biome names and IDs, have a look at the Wiki. Custom biomes can be specified by using single quotes (') around a biome ID.
Entities String One or multiple entity names, separated by comma (,). For a reference of entity names, have a look at the Wiki. Custom entities are supported, though they must be declared in single quotes (') and with their namespace id.
Structures String One or multiple structure names, separated by comma (,). A list of all valid structure names can be found here. Custom structures are supported, though they must be declared in single quotes (').
#Entities int The total amount of entities in that chunk.
#TileEntities int The total amount of tile entities in that chunk.

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.

MCA Selector window showing the nbt changer

You can change the following values:

Field Type Description
LightPopulated byte Whether the light levels for the chunk have been calculated. If this is set to 0, converting a world from 1.12.x to 1.13 will omit that chunk. Allowed values are 0 and 1
DataVersion int Allows to change the DataVersion of the chunks. Should be used with extreme care.
InhabitedTime long This field stores the amount of game-ticks players have spent in a chunk. Impacts the local difficulty.
LastUpdate long The time in ticks since world creation when the chunk was last saved.
Timestamp int The time in epoch seconds when the chunk was last saved.
Status String The status of the chunk generation. Only recognized by Minecraft 1.13+ (DataVersion 1444+)
Biome String/int A biome name or ID. This sets all biomes of this chunk to a single biome. For a reference of biome names and IDs, have a look at the Wiki. Custom biomes can be specified by using single quotes (') around a biome ID.
ReplaceBlocks String A comma separated list of block replacements in the format <block-name>=<block-name|block-nbt>[;<tile-nbt>]. Custom block names can be specified by surrounding them with single quotes.
DeleteEntities boolean If set to 1 or true, all entities in that chunk will be deleted.
DeleteSections boolean One or a range of section indices. A range has the format <from>:<to>, inclusive. Omitting <from> sets the lowest possible value, omitting <to> sets the highest possible value. : or true means all sections. Multiple ranges or single indices can be defined by separating them with a comma.
FixStatus boolean Will look for chunks that have terrain data, but their Status is set to empty and set their Status field to full. Having terrain data but the Status set to empty can sometimes happen when upgrading the world through a long upgrade path, e.g. from Minecraft 1.12 directly to 1.16.

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).

MCA Selector window showing the NBT editor

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.

MCA Selector window showing the chunk import

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.

MCA Selector window showing copy-paste overlay

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.

Overlays

To have a better overview of what's happening in your world, MCA Selector gives the option to enable customizable overlays. Overlays can display single values per chunk in the form of a color gradient with a minimum and maximum value.

MCA Selector window showing InhabitedTime overlay for Hermitcraft Season 6

Overlays can be con figured using Tools --> Edit overlays. By pressing the N key, it will switch to displaying the next overlay type. When pressing O while displaying an overlay, it will rotate all overlays of this type. Only when all values of an overlay are valid (e.g. minimum < maximum) and it is set to active it will be displayed in the main window.

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:

Minecraft Version DataVersion
1.2.1 - 1.12.2 None - 1343
1.13 - 1.13.2 1444 - 1631
1.14 - 1.14.4 1901 - 1976
1.15 - 1.15.2 2200 - 2230
1.16 - 1.16.5 2566 - 2586
1.17 - 1.17.1 2724 - 2730

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.

Mode Parameter Description
Create selection --mode select Create a selection from a filter query and save it as a CSV file.
Export chunks --mode export Export chunks based on a filter query and/or a selection.
Import chunks --mode import Import chunks with an optional offset.
Delete chunks --mode delete Delete chunks based on a filter query and/or a selection.
Change NBT --mode change Changes NBT values in an entire world or only in chunks based on a selection.
Cache images --mode cache Generates the cache images for an entire world.
Generate image --mode image Generates a single image based on a selection.

Mandatory and optional parameters

Create selection

Parameter Description Mandatory
--region <directory> The world's region folder for which to create the selection. Yes
--poi <directory> The world's poi folder. No
--entities <directory> The world's entities folder. No
--query <filter-query> The filter query to use to create a selection. Yes
--output <csv-file> The CSV-file to save the selection to. Yes
--radius <positive number> The radius for adjacent chunks to be selected No, default 0

Export chunks

Parameter Description Mandatory
--region <directory> The source world's region folder to export chunks from. Yes
--poi <directory> The source world's poi folder. No, but needs --output-poi if specified
--entities <directory> The source world's entities folder. No, but needs --output-entities if specified
--output-region <directory> The target region folder of the exported chunks. The directory MUST be empty. Yes
--output-poi <directory> The target poi folder. Yes if --poi is specified
--output-entities <directory> The target entities folder. Yes if --entities is specified
--query <filter-query> The filter query to use to export the chunks. Yes if --selection is not set, otherwise No
--selection <csv-file> The csv-file to load a selection from. Yes if --query is not set, otherwise No

Import chunks

Parameter Description Mandatory
--region <directory> The target world's region folder to import chunks to. Yes
--poi <directory> The target world's poi folder. No, but needs --input-poi if specified
--entities <directory> The target world's entities folder. No, but needs --input-entities if specified
--input-region <directory> The source region folder to import the chunks from. Yes
--input-poi <directory> The source poi folder. Yes if --poi is specified
--input-entities <directory> The source entities folder Yes if --entities is specified
--offset-x <number> The offset in chunks in x-direction. No, default 0
--offset-z <number> The offset in chunks in z-direction. No, default 0
--overwrite Whether to overwrite existing chunks. No, default false
--selection <csv-file> A specific selection where to import chunks to. No
--input-selection <csv-file> A specific selection for the source world listing what chunks to import into the target world. No
--sections <range|number[,...]> One or a range of section indices. A range has the format <from>:<to>, inclusive. Omitting <from> sets the lowest possible value, omitting <to> sets the highest possible value. : or true means all sections. Multiple ranges or single indices can be defined by separating them with a comma. No, default all sections

Delete chunks

Parameter Description Mandatory
--region <directory> The world's region folder to delete chunks from. Yes
--poi <directory> The world's poi folder. No
--entities <directory> The world's entities folder. No
--query <filter-query> The filter query to use to delete the chunks. Yes if --input is not set, otherwise No
--selection <csv-file> The csv-file to load a selection from. Yes if --query is not set, otherwise No

Change NBT

Parameter Description Mandatory
--region <directory> The world's region folder in which NBT values should be changed. Yes
--poi <directory> The world's poi folder. No
--entities <directory> The world's entities folder. No
--fields <values> The values to be changed. Yes
--selection <csv-file> The csv-file to load a selection from. No
--force Whether the value should be created if the key doesn't exist. No, default false

Cache images

Notice This requires a working JavaFX installation.

Parameter Description Mandatory
--region <directory> The world to create cache images from. Yes
--output <directory> Where the cache files will be saved. Yes
--zoom-level <1|2|4|8> The zoom level for which to generate the images. No, generates images for all zoom levels if not specified

Generate image from selection

Notice This requires a working JavaFX installation

Parameter Description Mandatory
--region <directory> The world to create cache images from. Yes
--output <png-file> Where the generated image will be saved. Yes
--selection <csv-file> The csv-file to a load a selection from. Yes

Configuration parameters

Parameter Description Mandatory
--debug Enables debug messages. No
--read-threads <number> The amount of Threads to be used for reading files. No, default 1
--process-threads <number> The amounts of Threads to be used for processing data. No, default is the amount of processor cores - 2, minimum 1
--write-threads <number> The amount of Threads to be used for writing data to disk. No, default ìs the amount of processor cores, maximum 4
--max-loaded-files <number> The maximum amount of simultaneously loaded files. No, default is the maximum heap size in GB * 2, minimum 1

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 translating)
  • Japanese (Japan) (thanks to @Uguisu64J for translating)

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.


Sponsoring

IntelliJ IDEA Logo IntelliJ IDEA Ultimate was sponsored by JetBrains through their Open Source program.

Download and installation

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


Download Version 1.16.3 (Windows Installer)

"Requirements":

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

Download Version 1.16.3 (Universal)

"Requirements":

  • Either:
    • 64bit JRE 16+, with JavaFX either pre-packed or installed separately
    • 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

Using a JRE or JDK with pre-packed JavaFX (the simple way)

The following steps describe a way to run MCA Selector using a JRE or JDK with pre-packed JavaFX.

With zulu JRE-FX: For Windows:

  • Download the JRE-FX-16 from HERE into an empty folder.
  • Move the previously downloaded mcaselector-1.16.3.jar into the same folder. Extract the content of the downloaded .zip file into this folder.
  • Hold Shift and right-click an empty spot in this folder, and choose Open PowerShell window here. Type & (with a space at the end), go into the previously extracted folder and drag and drop the bin\java.exe file into the PowerShell window. Then complete the command by typing a space and -jar mcaselector-1.16.3.jar and press Enter.

For MacOS:

  • Download the JDK-FX-16 from HERE into an empty folder.
  • Extract the content of the downloaded .zip file into this folder.
  • Press Cmd+Space, type Terminal and press Enter. Go into the previously extracted folder and drag and drop the zulu-16.jdk/Contents/Home/bin/java into the terminal. Continue to type -jar (with a space at the end) and drag-and drop the mcaselector-1.16.3.jar into the terminal as well, the press Enter.

For Linux:

  • Download the JDK-FX-16 from HERE into an empty folder.
  • Extract the content of the downloaded .tar.gz file into this folder.
  • Open your terminal of choice and navigate in the extracted folder into bin, then run ./java -jar <path-to-mcaselector-1.16.3.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.

When you receive an error from a previously installed version of Java

"When I run mcaselector-1.16.3.jar, an error dialog appears that looks like this:"

Popup dialog stating a missing JavaFX installation

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 a Java version older than 16, make sure that you have Java 16 installed or proceed with Using a JRE or JDK with pre-packed JavaFX (the simple way).

For Windows and MacOS:

  • Type java -jar (with a space at the end) and drag and drop the mcaselector-1.16.3.jar into the console and hit Enter.

For Linux:

  • Run java -jar <path to mcaselector-1.16.3.jar where you replace everything in <>.

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-1.16.3.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-1.16.3.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-1.16.3.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-1.16.3.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.