Press Kit - OSIK
ISOK – Inverse Kinematics node for Godot 4.5
ISOK is a free, open-source project that showcases a custom-built Inverse Kinematics (IK) system for Godot 4.5.
It’s designed to help other developers understand how to implement and modify IK behaviour within their own projects, including how to manage bone constraints, global-to-local transformations, and directional clamping.
This project acts as both a learning resource and a proof of concept, showing how a clean GDScript-based IK solution can be structured without relying on engine-side IK nodes.
Now Avalible through the Assetlib!
OSIK is now avalible through the native asset libaray inside godot making it even easier to install and use!
Also on the godot beta store!
Link to Beta store
https://store-beta.godotengine.org/asset/okay-salmon/osik/
🧩 Key Features
FABRIK-based solver (Forward and Backward Reaching Inverse Kinematics).
Custom joint constraints for pitch and yaw.
Local/global transform handling for clean skeletal control.
Simple debugging tools for visualising IK targets and bone alignment.
Fully commented GDScript to make learning and modification easier.
Lightweight & plug-and-play — no external addons required.
🧠 How It Works
The solver calculates bone positions using an iterative FABRIK method:
The backward pass reaches from the target to the rootbone down the bone chain.
The forward pass then corrects positions from the root bone down the chain back to the target.
Each bone’s transform is then converted from global to local space before being applied to the skeleton.
If constraints are turned off (as they are by default), the solver will simply pass through the original yaw and pitch (X-Z and Y-Z) information.
📂 What’s Included
Complete Godot 4.5 project
Example scene and skeleton setup
Well-documented GDScript source files
⚙️ Requirements
Godot 4.5 or newer
A basic understanding of 3D transforms and skeleton nodes.
📜 License
Released under the MIT License — free to use, modify, and share, even in commercial projects
Click here to read
🌐 Links
GitHub Repo: https://github.com/okaysalmon/ISOK
Discord Community: https://discord.gg/szmwc5WvKz
YouTube Overview: https://youtu.be/vUFtTkPb2Bg?si=D_mL3tsiYYaQwq3H
YouTube Short: https://youtube.com/shorts/UB84QD2Is40
Redit Post: https://www.reddit.com/r/godot/comments/1o9eqpo/free_inverse_kinematics_node/
💾 Down Load Link media assets
NOTE: The scaling issue shown in the video is now fixed