[1.21.5] Add model loading plugins to replace ModelEvent.ModifyBakingResult

[XFactHD]

This PR adds model loading plugins which are intended to replace ModelEvent.ModifyBakingResult. These allow more precise model wrapping, including wrapping unbaked models. Another benefit of this API design is that it allows mods which implement on-demand model loading/baking a lot more control and improves compatibility between those mods and ones using the model wrapping APIs.
As is probably very obvious, this PR is very heavily inspired by Fabric API's model loading APIs and therefor has an almost 100% overlap in terms of API surface and injection points.

The model loading plugins provide seven entrypoints into the model loading and baking process:

• On-load/on-load-block modifiers: on-load modifiers are registered globally and allow wrapping unbaked models and unbaked blockstate models as they are loaded and therefor affect all further uses of the model in question
• Pre-bake-block/pre-bake-item modifiers: pre-bake modifiers are registered globally and allow wrapping unbaked blockstate models and unbaked item models respectively right before baking and therefor only affect the specific baking process following their execution
• Post-bake-block/post-bake-item modifiers: post-bake modifiers are registered globally and allow wrapping baked blockstate models and baked item models respectively right after baking (effectively equivalent to wrapping models in ModelEvent.ModifyBakingResult)

Apart from the missing documentation, there are still a few questions open:

• Should we try to aggressively re-use context objects?
• What would be the preferred way of exposing the plugins to mods implementing on-demand loading/baking?

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

Last commit published: 7947f32e41a0a9fc23a37f15c2b8c71fdf51eaf6.

PR Publishing

The artifacts published by this PR:

• 📦 net.neoforged:neoforge:21.5.29-beta-pr-1884-model_loading_plugins
• 📦 net.neoforged:testframework:21.5.29-beta-pr-1884-model_loading_plugins

Repository Declaration

In order to use the artifacts published by the PR, add the following repository to your buildscript:

repositories {
    maven {
        name 'Maven for PR #1884' // https://github.com/neoforged/NeoForge/pull/1884
        url 'https://prmaven.neoforged.net/NeoForge/pr1884'
        content {
            includeModule('net.neoforged', 'neoforge')
            includeModule('net.neoforged', 'testframework')
        }
    }
}

MDK installation

In order to setup a MDK using the latest PR version, run the following commands in a terminal.
The script works on both *nix and Windows as long as you have the JDK bin folder on the path.
The script will clone the MDK in a folder named NeoForge-pr1884.
On Powershell you will need to remove the -L flag from the curl invocation.

mkdir NeoForge-pr1884
cd NeoForge-pr1884
curl -L https://prmaven.neoforged.net/NeoForge/pr1884/net/neoforged/neoforge/21.5.29-beta-pr-1884-model_loading_plugins/mdk-pr1884.zip -o mdk.zip
jar xf mdk.zip
rm mdk.zip || del mdk.zip

To test a production environment, you can download the installer from here.

[neoforged-compatibility-checks]

@XFactHD, this PR introduces breaking changes.
Fortunately, this project is currently accepting breaking changes, but if they are not intentional, please revert them.
Last checked commit: 7947f32e41a0a9fc23a37f15c2b8c71fdf51eaf6.

neoforge (:neoforge)

• net/minecraft/client/resources/model/ModelBakery
  • <init>(Lnet/minecraft/client/model/geom/EntityModelSet;Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Lnet/minecraft/client/resources/model/ResolvedModel;Lnet/neoforged/neoforge/client/model/standalone/StandaloneModelLoader$LoadedModels;)V: ❗ API method was removed

[Fuzss]

Any update on merging this?

[embeddedt]

This is probably not going to be merged in the current state because of the drastic vanilla changes to model handling in 1.21.5, which is right around the corner.

[Technici4n]

We should make sure that each of these has a clear use case.

[Technici4n]

We could also fold standalone models into the plugin system. (Possibly just deprecating the current API, or rewriting it as a wrapper on top of a plugin).

[Technici4n]

Of course javadoc is still missing everywhere.