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A Minecraft mod to record game sessions and replay them afterwards from any perspective.


Make sure your sub-projects are up-to-date: git submodule update --init --recursive

For compiling 1.7.10, you must run ./gradlew :jGui:1.7.10:setupDecompWorkspace :1.7.10:setupDecompWorkspace once after the initial clone. This may take quite some time.


You can build the mod by running ./gradlew build (or just ./gradlew shadowJar). You can then find the final jar files in versions/$MCVERSION/build/libs/. You can also build single versions by running ./gradlew :1.8:build (or just ./gradlew :1.8:shadowJar) (builds the MC 1.8 version).


Ensure you have at least IDEA 2020.1. Build the mod via Gradle as explained above at least once (./gradlew compileJava should be sufficient). This will ensure that the sources for all MC versions are generated. Then import the Gradle project from within IDEA: File -> Open -> build.gradle -> Open as Project Finally configure IDEA to build everything by itself instead of delegating it to Gradle (cause that is slow): File -> Settings -> Build, Execution, Deployment -> Build Tools -> Gradle -> Build and run using: IntelliJ IDEA

The generation of run configurations for 1.14+ currently depends on




Loosely based on this branching model with stable instead of master.

TL;DR: Main development happens on the develop branch, snapshots are built from this branch. The stable branch contains the most recent release.

The master branch is solely to be used for the version.json file that contains a list of all versions used by the clients to check for updates of this mod.

The Preprocessor

To support multiple Minecraft versions with the ReplayMod, a JCP-inspired preprocessor is used:

        //#if MC>=11200
        // This is the block for MC >= 1.12.0
        category.addDetail(name, callable::call);
        //$$ // This is the block for MC < 1.12.0
        //$$ category.setDetail(name, callable::call);

Any comments starting with //$$ will automatically be introduced / removed based on the surrounding condition(s). Normal comments are left untouched. The //#else branch is optional.

Conditions can be nested arbitrarily but their indention shall always be equal to the indention of the code at the //#if line. The //$$ shall be aligned with the inner-most //#if.

    //#if MC>=10904
    public CPacketResourcePackStatus makeStatusPacket(String hash, Action action) {
        //#if MC>=11002
        return new CPacketResourcePackStatus(action);
        //$$ return new CPacketResourcePackStatus(hash, action);
    //$$ public C19PacketResourcePackStatus makeStatusPacket(String hash, Action action) {
    //$$     return new C19PacketResourcePackStatus(hash, action);
    //$$ }

Code for the more recent MC version shall be placed in the first branch of the if-else-construct. Version-dependent import statements shall be placed separately from and after all other imports. Common version dependent code (including the fml and forge event bus) are available as static methods/fields in the MCVer class.

The source code in src/main is generally for the most recent Minecraft version and is automatically passed through the preprocessor when any of the other versions are built (gradle projects :1.8, :1.8.9, etc.). Do NOT edit any of the code in versions/$MCVERSION/build/ as it is automatically generated and will be overwritten without warning.

You can change the version of the code in src/main if you wish to develop/debug with another version of Minecraft:

./gradle :1.9.4:setCoreVersion # switches all sources in src/main to 1.9.4

If you do so, you'll also have to refresh the project in your IDE.

Make sure to switch back to the most recent branch before committing! Care should also be taken that switching to a different branch and back doesn't introduce any uncommitted changes (e.g. due to different indention, especially in case of nested conditions).

Some files may use the same preprocessor with different keywords. If required, more file extensions and keywords can be added in the preprocess block of the versions/common.gradle script.


The ReplayMod uses the versioning scheme outlined here with three changes:

  • No MAJORAPI, the ReplayMod does not provide any external API
  • "Updating to a new Minecraft version" should not increment MAJORMOD, we maintain one version of the ReplayMod for each version of Minecraft and all these versions share the same feature set (and most bugs). We therefore try to keep the version name the same for all of them (with the exception of MCVERSION of course). This also means that the "Multiple Minecraft Version" section does not apply.
  • For pre-releases the shorter -bX is used instead of -betaX

When a new version is (pre-)release, a new commit modifying the version.txt file should be added and the versions.json file in the master branch should be updated. To simplify this process the gradle task doRelease can be used: ./gradlew -PreleaseVersion=2.0.0-rc1 doRelease. It will create the commit and update the version.json accordingly.

Care should be taken that the updated version.json is not pushed before a jar file is available on the download page (or Jenkins) as it will inform the users of the update.


GitHub should generally be used to report bugs.

In the past, bugs were tracked via Bugzilla, so bug numbers in commits prior to 2020 such as (fixes #42) generally referred to Bugzilla unless noted otherwise.


The ReplayMod is provided under the terms of the GNU General Public License Version 3 or (at your option) any later version. See for the full license text.

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