A small tool for developing NeoForge mods using Fabric conventions.
Launchpad's main features include the following:
- Reading mod metadata from
fabric.mod.jsonfiles - Running mod entrypoints (both standard and custom)
- Access transformation using Class Tweakers (or Access Wideners)
- Loading nested jar dependencies
Furthermore, we provide certain extensions on top of the Fabric standard described in Usage.
Generally speaking, Launchpad works best for small to medium-sized Fabric mods that are already potentially compatible with NeoForge, just need that small final push to get them loaded.
Use Launchpad, when:
- You want to port your mod to NeoForge but don't have the time for a full, native port
- Your mod requires little to no changes to be compatible with NeoForge (mainly speaking of Mixins)
- You're fine with having extra dependencies on NeoForge, namely the Forgified Fabric API and Launchpad
Consider making a native port or using the MultiLoader template, when:
- You want to use NeoForge APIs extensively
- You want full control over your metadata or entrypoints
- You don't want extra dependencies
Install Launchpad in your development environment by including it in your dependencies. You can find available versions on our maven or on GitHub releases.
Use the following code to add Launchpad to a ModDevGradle workspace:
repositories {
maven {
name = "Sinytra"
url = "https://maven.sinytra.org/"
}
}
dependencies {
implementation "org.sinytra.launchpad:launchpad:<version>"
}Running mods on Launchpad requires explicit opt-in from the mod author. Launchpad automatically scans Fabric mods located by FML and uses a custom metatada property to decide whether they should be loaded.
To enable loading your mod on Launchpad, add the following to your fabric.mod.json file.
{
"custom": {
"launchpad:compatible": true
}
}From here on, Launchpad will handle everything else for you.
By default, Launchpad will make minimal changes to your metadata in order to comply with NeoForge's requirements. Currently, the following patches are applied:
- Replacing
-with_in the mod ID and dependency IDs to match the required format. The original mod ID is added as an alias so that runtime checks are not affected.
You can disable this behavior and take full control of your metadata by setting the following property:
{
"custom": {
"launchpad:normalize": false
}
}Property overrides can be used to provide different values for a property depending on the mod loader used. Launchpad will overwrite the actual value with its override counterpart when it reads the metadata file.
Example use cases include changing dependencies or the mod ID.
You can define overrides using the launchpad:overrides custom property. Its body follows the same format as the
outer Fabric Mod Json.
{
"name": "Example Mod Fabric",
"custom": {
"launchpad:overrides": {
"name": "Example Mod NeoForge",
}
}
}If a user installs a Launchpad-compatible Fabric mod, but forgets to install Launchpad itself, FML has no way to tell them about the missing dependency, and will instead show an error screen saying the mod is invalid.
To overcome this issue, Launchpad offers a placeholder/stub feature that allows developers to safely depend on Launchpad
and notify users about missing dependencies when Launchpad is not installed. To enable this, include a standard
neoforge.mods.toml metadata file in your mod jar. In addition to the mod declaration, add the following code:
[properties]
"launchpad:placeholder"=trueAt discovery time, Launchpad will recognize this as a placeholder, ignore the NeoForge metadata file and load your mod
using fabric.mod.json instead.
In addition to the property above, don't forget to actually declare a dependency on Launchpad. For convenience, you can use this snippet:
# Replace with your actual mod id
[[dependencies.your_mod_id]]
modId="launchpad"
type="required"
versionRange="[0,)"
ordering="NONE"
side="BOTH"Launchpad is designed to be a developer porting tool, not a compatibility layer. Unlike Connector, it makes no modifications to the mod's code and only converts metadata files to NeoForge's format at runtime. No changes are made to the mod's jar, either.
This means resolving potential compatibility issues, such as in Mixins, is the left up to mod authors. In return, we can provide a very minimal and stable tool for running their mods on NeoForge without making any invasive and unpredictable changes to them that the author can't control.
Launchpad will, however, do its best to provide runtime conditions replicating those of Fabric as closely as possible. This mainly concerns game object registration logic, which differs significantly on NeoForge. More on that below.
Fabric metadata is translated to NeoForge as accurately as possible, but due to the differences in the two formats, the result may be missing information from properties that don't have a NeoForge counterpart.
Dependencies will be translated as well, with dependency resolution being handled by FML natively.
The main, client and server entrypoint will run at the same time as on Fabric.
The preLaunch entrypoint is a special case because it runs before the game's entrypoint is called. On Launchpad, we
invoke it from inside a Mixin config plugin's static initialization block. We guarantee that the most common use cases
for this entrypoint, such as loading native libraries or additional Mixin config files, work correctly.
Usually, registering game objects on NeoForge must be done inside the RegisterEvent, during which the registries are
unfrozen. However, Fabric mods run out their registration logic in their initializers. At the time of their invocation,
the registries are frozen and NeoForge's builtin registry callbacks haven't been added yet.
Launchpad resolves these issues and ensures the registries are ready to receive registration calls when a mod's entrypoints run.
Launchpad makes Fabric Loader API available using our NeoForge port of the Fabric Loader, Forgified Fabric Loader. This is also used to manage the metadata and entrypoints of mods loaded via Launchpad, but also to provide Fabric-facing information of native FML mods. As a result, Fabric mods can access the metadata of both "Fabric" and FML mods through just the Fabric Loader.
Despite our best efforts, certain environmental settings may still differ. If you run into any issues, please file a bug report!
To integrate with Launchpad programatically, you can use the API provided in the org.sinytra.launchpad.api package.
Launchpad is licensed under the GNU General Public License v3 with the Classpath Exception v2.0. See LICENSE for the full license text.
