This guide provides information on how to create modifications for Minecraft Diverge.
- JDK 8 (more recent versions do not support modding) (preferrably downloaded from Adoptium, the JDK used to compile Minecraft Diverge)
- RetroMCP 1.0.1 (https://github.com/MCPHackers/RetroMCP-Java; download 1.0.1 from the "Actions" tab, select the latest workflow, download the build artifacts and use the "GUI" jar if 1.0.1 has not released it)
- Minecraft Diverge's patch file
- Both the Minecraft Diverge client and server
- (Optional, but recommended) A Java IDE, like IntelliJ or Eclipse.
First, the RetroMCP jar needs to be placed in a new folder. Before decompiling, the Side setting in the Options menu needs to be set to Merged and the source and target Java versions in the Recompile section need to be set to 8 with Java Home set to JDK 8. Then, go to the "Current version" dropdown and select "Alpha 1.1.2_01". Upon being prompted to run the setup, click yes. RetroMCP will show up a notification when setup is completed, and at that stage RetroMCP should be closed. After this, in the directory RetroMCP is in, two folders called minecraft and minecraft_server need to be created with each containing a folder called jars, since RetroMCP does not create them automatically despite requiring them.
In the jars folder (not in minecraft or minecraft_server), there should be a jar file for the client named minecraft.jar and a jar file for the server named minecraft_server.jar. Each jar needs to be opened in a file archiver and the contents of mcdiverge.zip and mcdiverge_server.zip need to be copied over to the respective jar. Make sure to delete META-INF in minecraft.jar, but not in minecraft_server.jar.
With Diverge ready to decompile, open up RetroMCP again and click on the Decompile button. Wait for it to do its work, however the decompilation will fail as there are many missing classes, duplicate members and missing generics. This is supposed to happen, as Minecraft Diverge has changed the source code so much that it is bound to have some major differences from the vanilla source code which RetroMCP cannot cope with. This is fine, as there is a different way to get Minecraft Diverge's source code that actually works.
Create a new folder and copy RetroMCP into it. Open up RetroMCP, set the side to merged, select "Alpha 1.1.2_01" as the current version and click "Decompile". Once decompilation is finished, create a patches folder, where the patch file for Minecraft Diverge needs to be moved into and named merged.patch. Back in RetroMCP, to the top left of the window, click on MCP > More tasks... > Apply patch to apply the patch file.
In the minecraft_merged folder, there is a src folder. This folder needs to be copied over to the minecraft_merged folder in the Minecraft Diverge decompilation after its src and src_original folders have been deleted. After that, the src folder needs to be copied as a new folder called src_original, so that RetroMCP will now use the fixed source code for recompiling as well as source code patch creation. Open up RetroMCP again and press the following buttons in this order while accepting any prompts that appear: Recompile, Update MD5, Reobfuscate, Build. After all of this, click MCP > Launch client and a decompiled version of Minecraft Diverge should be running!
To start off creating a mod, add a new class in the folder minecraft_merged/src/net/minecraft/src. This class needs to inherit BaseMod and override the following methods:
@Override // Name of the mod
public String getName() {
return "Example Mod";
}
@Override // Mod version
public String getVersion() {
return "v0.3_a4";
}
@Override // Author of the mod
public String getAuthor() {
return "BlueStaggo";
}
@Override // Mod icon for mod list (optional)
public String getIcon() {
return "/example_mod/icon.png";
}
@Override // Is the mod for the client or server? (defaults to both)
public ModSide getSide() {
return ModSide.BOTH;
}
@Override // Load the actual mod
public void load() throws Exception {
// Load your mod!
}All resources are loaded relative to the first src folder, so if the mod class was used as the icon, its path would be /net/minecraft/src/YourMod.class. In the case above, relative to the RetroMCP jar, the icon would need to be stored in /minecraft_merged/src/example_mod/icon.png.
Upon running the game, however, the mod will not load. To force the mod to load, go to ModLoader.java, and before the code that loads the example mod, add in this code:
// ...
}
}
}
// v v v
mods.add(new YourMod());
modCount++;
// ^ ^ ^
if (loadExampleMod) {
mods.add(new ExampleMod());
modCount++;
}
// ...Make sure to remove this extra code before publishing the mod. If ModLoader.class appears in the final jar, it is safe to delete it.
To compile the code and run the game, click on Recompile, Reobfuscate and Build in RetroMCP. When the game is opened, check in the mods list and the mod should appear with its icon:
What should the mod do? One simple thing it can do is create an achievement and grant it to the player when the game loads. This is very trivial, as this is all the code that needs to be added in the mod:
public static Achievement exampleAchievement;
@Override
public void load() {
exampleAchievement = new Achievement("example_mod/got_modded", "Got Modded", "Now it is Yourcraft!")
.setCreativeUnlockable();
ModLoader.registry.addAchievement(exampleAchievement); // Make sure it is saved correctly
if (ModLoader.isClient()) {
Minecraft.getInstance().achievements.updateProgress(exampleAchievement, 1);
}
}As for the assets, relative to the src folder, these images need to be stored in the directory /achievements/example_mod/ as got_modded.png and got_modded_locked.png respectively:
Now when the game is loaded this time, this should appear in the achievements menu:
First, make sure the mod is not loaded from the ModLoader class. Like before, Recompile, Reobfuscate and Build in RetroMCP. In the build folder relative to the RetroMCP jar, two files can be found: minecraft.zip and minecraft_server.zip. Both of these files contain every class you have modified, but if there are any classes in there that you have not modified then make sure to delete them. Finally, the mod can be shared across the web, but one of the best places to share it in is in the Minecraft Diverge Discord server.
With the mod class approach, it is impossible to override vanilla Minecraft Diverge classes. Instead, Minecraft Diverge can be modded with the traditional jar mod approach, where any class can be modified. Jar mods are not loaded from the mods folder, but are rather added directly onto the Minecraft Diverge jar.
This guide only shows so much, so looking through the Example Mod and Minecraft Diverge's source code is recommended.