Add ik humanoid.

[fire]

See V-Sekai/godot#54 (comment) and the tracker godotengine/godot#112302

Model:
https://hub.vroid.com/characters/3609285562418162352/models/5465162707471684141

[fire]

diff --git a/3d/ik_humanoid/lyuma_anim_godot/CC0_LICENSE.txt b/3d/ik_humanoid/lyuma_anim_godot/CC0_LICENSE.txt
index 0c5dde0..e4c0b2b 100644
--- a/3d/ik_humanoid/lyuma_anim_godot/CC0_LICENSE.txt
+++ b/3d/ik_humanoid/lyuma_anim_godot/CC0_LICENSE.txt
@@ -1,2 +1,2 @@
 The lyuma animation set is licensed with CC0
-https://creativecommons.org/public-domain/cc0/
\ No newline at end of file
+https://creativecommons.org/public-domain/cc0/

[GeorgeS2019]

What else missing to merge this PR???

godotengine/godot#112302 (comment)

[aaronfranke]

@GeorgeS2019 Quite a lot is missing:

1. The tracker for prerequisite engine issues is not yet resolved.
2. Once that tracker is resolved, we need to wait for it to appear in a stable engine version before merging this demos PR.
3. This PR is a draft, indicating it is not ready for review.
4. This PR does not pass CI checks
5. This PR has not yet been reviewed.

[GeorgeS2019]

@GeorgeS2019 Quite a lot is missing:

1. The tracker for prerequisite engine issues is not yet resolved.
2. Once that tracker is resolved, we need to wait for it to appear in a stable engine version before merging this demos PR.
3. This PR is a draft, indicating it is not ready for review.
4. This PR does not pass CI checks
5. This PR has not yet been reviewed.

Thx, this overview helps users who care where to focus

[GeorgeS2019]

@TokageItLab

Feedback, for each of the 8 subclasses, create a specific small demo rather than putting all use case into ONE big Godot demo project.

Also, do not replace the existing 3D IK! <================

Instead, a seperate 3D IK use cases

Why: 3D IK for Godot 4 is very challenging for the Godot community as seen in the list of youtube below

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Dev snapshot: Godot 4.6 dev 4 14th Nov 2025

We are introduce Animation: Add SkeletonModifier3D IKs as IKModifier3D

SkeletonModifier3D receiving 8 new subclasses

godotengine/godot#110120
godotengine/godot#113284

• IKModifier3D
  • ChainIK3D
  • IterateIK3D
    • CCDIK3D
    • FABRIK3D
    • JacobianIK3D
  • SplineIK3D
• TwoBoneIK3D

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Before 14th Nov 2025

List of youtube tutorial on SkeletonModifier3D

• How to Create Custom Bone3D Behaviors with SkeletonModifier3D in GODOT 4.3
• Advanced Godot's SkeletonModifier3D: create, debug and optimize them with this godly tech!

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• How do I point a bone at a target using Godot's SkeletonModifier3D?

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• Transition to Godot's superior 3d animation system - SkeletonModifier3D

[GeorgeS2019]

Interesting mini godot project to be considered as IK use case

V-Sekai/godot#54 (comment)

[GeorgeS2019]

The vision of how Godot 4 IK will be integrated to humanoid animation

[GeorgeS2019]

Look forwards to test in Godot 4.6 Dev 6

godotengine/godot#110336 (comment)

[GeorgeS2019]

Unity provides equivalents to Godot 4.6’s IKModifier3D subclasses through its Animation Rigging package and third‑party solutions like Final IK. Below is a mapping of each Godot class to Unity’s closest IK constraint or solver, with illustrative image links for each use case.

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🔗 Godot vs Unity IK Mapping

Godot 4.6 Class	Unity Equivalent	Example Image/Documentation
IKModifier3D	General IK constraints in Unity’s Animation Rigging package (TwoBoneIK, ChainIK, etc.)	Unity IK overview docs.unity3d.com
ChainIK3D	ChainIKConstraint in Animation Rigging	Unity ChainIK example
IterateIK3D	Iterative solvers in Final IK (e.g., CCD iterations)	Unity CCDIK iterative rigs
CCDIK3D	CCDIK in Final IK	Unity CCDIK tutorial
FABRIK3D	FABRIK solver in Final IK or custom FABRIK implementations	Unity FABRIK demo
JacobianIK3D	Custom Jacobian IK implementations (academic/Unity3DAnimation examples)	Jacobian IK overview
SplineIK3D	Unity Splines package + rigging constraints	Unity Splines tutorial
TwoBoneIK3D	TwoBoneIKConstraint in Animation Rigging	Unity TwoBoneIK example

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📸 Visual Examples

Here are some direct illustrations of Unity IK in action:

• ChainIK rigging in Unity

**Unity provides equivalents to Godot 4.6’s IKModifier3D subclasses through its Animation Rigging package and third‑party solutions like Final IK. Below is a mapping of each Godot class to Unity’s closest IK constraint or solver, with illustrative image links for each use case.**

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🔗 Godot vs Unity IK Mapping

Godot 4.6 Class	Unity Equivalent	Example Image/Documentation
IKModifier3D	General IK constraints in Unity’s Animation Rigging package (TwoBoneIK, ChainIK, etc.)	[Unity IK overview](https://docs.unity3d.com/6000.2/Documentation/Manual/InverseKinematics.html)
ChainIK3D	ChainIKConstraint in Animation Rigging	[Unity ChainIK example](https://docs.unity3d.com/Packages/[email protected]/manual/constraints/ChainIKConstraint.html)
IterateIK3D	Iterative solvers in Final IK (e.g., CCD iterations)	[Unity CCDIK iterative rigs](https://www.youtube.com/watch?v=-z_l7Jdz8Bo)
CCDIK3D	CCDIK in Final IK	[Unity CCDIK tutorial](https://www.youtube.com/watch?v=MA1nT9RAF3k)
FABRIK3D	FABRIK solver in Final IK or custom FABRIK implementations	[Unity FABRIK demo](https://www.youtube.com/watch?v=rYnmHs97CVI)
JacobianIK3D	Custom Jacobian IK implementations (academic/Unity3DAnimation examples)	[Jacobian IK overview](https://medium.com/unity3danimation/overview-of-jacobian-ik-a33939639ab2)
SplineIK3D	Unity Splines package + rigging constraints	[Unity Splines tutorial](https://catlikecoding.com/unity/tutorials/curves-and-splines/)
TwoBoneIK3D	TwoBoneIKConstraint in Animation Rigging	[Unity TwoBoneIK example](https://docs.unity3d.com/Packages/[email protected]/manual/constraints/TwoBoneIKConstraint.html)

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📸 Visual Examples

Here are some direct illustrations of Unity IK in action:

• ChainIK rigging in Unity

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• CCDIK rigs with Final IK: [YouTube demo](https://www.youtube.com/watch?v=-z_l7Jdz8Bo)
• FABRIK solver for multi‑effector rigs: [GitHub FABRIK implementation](https://github.com/nfynt/FABRIK)
• Jacobian IK math and Unity examples: [Medium article](https://medium.com/unity3danimation/overview-of-jacobian-ik-a33939639ab2)
• Spline IK workflows: [Catlike Coding tutorial](https://catlikecoding.com/unity/tutorials/curves-and-splines/)
• TwoBoneIK for arms/legs: [Unity Manual](https://docs.unity3d.com/Packages/[email protected]/manual/constraints/TwoBoneIKConstraint.html)

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⚡ Key Takeaway

• Godot 4.6’s SkeletonModifier3D subclasses (ChainIK3D, CCDIK3D, FABRIK3D, etc.) map directly to Unity’s Animation Rigging constraints or Final IK solvers.
• Unity’s Animation Rigging package covers most standard IK (ChainIK, TwoBoneIK).
• Final IK adds advanced solvers (FABRIK, CCDIK, Full Body IK).
• Jacobian and Spline IK are more specialized, often implemented via custom scripts or Unity’s Splines package.