I've reimplemented Nylon, but at what cost?

Crystalize uses display entities to display models from Blockbench (non-cube meshes are not supported, obviously) on your Minecraft server. Simply drag and drop Blockbench model to your mod, use ModelsManager.registerModel() and you are ready to go! Sounds simple but I wasted more than 40 hours of my life just to cook this library mod (and it's not even finished yet).

Custom model animation completely client-side!

Load models directly from your Blockbench project file! Crystalize will automatically construct all model parts as JSON models and assign it to custom model data value of minecraft:command_block.

Tired of animating each part one by one? Now you can use FabrikController (FABRIK is the name of the IK algorithm)! This IK controller automatically animates your model parts such that the end position of the chain reaches your target position. IK constraints is supported but you might need to convert direction vector to rotation and vice versa.

Inverse Kinematics (unconstrained)

It is pretty simple to attach Crystalize model to your entity. Here is an example:

public class RoboticArmEntity extends Entity implements PolymerEntity {
	private static final Identifier MODEL_ID = new Identifier(CrystalizeSampleMod.MODID, "robotic_arm");
	private CrystalizeElementHolder modelHolder;
	private Vector3f target = new Vector3f();

	public RoboticArmEntity(EntityType<? extends RoboticArmEntity> type, World world) {
		super(type, world);
		EntityAttachment.ofTicking(modelHolder = new CrystalizeElementHolder(MODEL_ID, TranslateStrategy.TRANSLATION_ONLY), this);

		// Let's make our robotic arm tracking nearby players!
		// Get these IDs from robotic_arm.bbmodel
		modelHolder.addAnimation(new FabrikController(Arrays.asList(
			"984422d6-82df-2fc5-9509-809912aa01fd",
			"fd6d3d3e-aa57-518e-b758-3e56901278ea",
			"e99bebd5-5564-9731-9819-3bb487096f1c"), target));
	}

	public RoboticArmEntity(World world, Vec3d pos) {
		this(TYPE, world);
		setPosition(pos);
	}

	@Override
	public EntityType<?> getPolymerEntityType(ServerPlayerEntity player) {
		return EntityType.INTERACTION;
	}

	// Stripped initDataTracker, readCustomDataFromNbt and writeCustomDataToNbt.

	@Override
	public void tick() {
		super.tick();
		PlayerEntity closest = getWorld().getClosestPlayer(getX(), getY(), getZ(), 3d, false);
		if (closest == null) return;
		target.set(closest.getPos().toVector3f()).sub(getPos().toVector3f());
	}
}

See this code, which is the code above but with comments.

The common code for all platforms and components. Includes Crystalize model structure, animations and animation controllers.

Includes codecs for reading Blockbench's "Generic Model" project, as well as component for building to Crystalize model (which is Model).

Includes codecs for reading and writing Minecraft JSON models + texture atlases, as well as builder for building ElementGroup into JSON model.

Powered by Polymer Virtual Entity, this component allows you to load your Crystalize model in your Fabric server and control it. See crystalize-fabric-samplemod for example usage.

Bukkit implementation. Work in progress but the priority for this platform is not high.

The Crystalize and its components' code are licensed under MIT license.

Mojang's DataFixerUpper and JOML are licensed under MIT license.

Patbox's Polymer and its components are licensed under LGPL 3.0.

The sample models are mainly licensed under CC0 1.0 Universal license, except:

• The "Taterinator" 3D model uses "Tiny Potato" texture from Botania by Vazkii/Violet Moon, which is licensed under custom license. I honestly don't know if they are willing to let me license the model under CC0 1.0, but like, it's just a :), right? RIGHT?
• The "tiny_potatog" test model uses frog entity model from Mojang Studios. (c) Mojang Studios/Microsoft Corporation.

Paper: "FABRIK: A fast, iterative solver for the Inverse Kinematics problem" by Aristidou, Andreas and Lasenby, Joan. DOI.