Cats Blender Expanded

A maintained continuation of the CATS Blender Plugin — one-click import and optimization of 3D avatars for VRChat, Resonite, and more.

Cats Blender Expanded is a maintained continuation and expansion of the CATS Blender Plugin, assembled by Unity AI Lab. It merges the three now-unmaintained CATS lineages (the archived absolute-quantum original, the Team Neoneko fork, and the Yusarina mirror) and folds in features from Avatar-Toolkit. CATS compresses the hours-long process of importing and optimizing avatar models for social-VR platforms into a handful of one-click tools inside Blender.

Why this exists: every upstream CATS variant is now unmaintained — the original was archived, and the Team Neoneko fork's own README states it is "no longer maintained, feel free to fork." This is that fork, continued and expanded.

What it does

All tools live under the CATS tab in the Blender 3D View sidebar (press N).

• Model import — import avatars and models across common formats, including MMD models via the bundled MMD Tools.
• Fix Model / armature repair — standardize and repair armatures, rename bones to known conventions, merge and clean up bone hierarchies, and run manual bone operations.
• Optimization — texture atlasing, material combining (with optional integration for Shotariya's Material Combiner when installed), bone merging, and root-bone tools.
• Decimation — reduce mesh polygon counts to hit platform budgets.
• Bake — multi-pass texture baking (diffuse, normal, AO, metallic, emit, and more).
• UV tools — UV edge alignment utilities.
• VRM ↔ Unity converter — rename bones between VRM and Unity conventions.
• Resonite loader/exporter — bone conversion, glTF/WEBP export, and .animx animation import (lz4-compressed .animx supported via bundled wheels).
• Eye tracking — set up eye-tracking bones and constraints.
• Visemes & shape keys — generate mouth visemes for lip-sync and manage shape keys.
• Model scaling — scaling utilities plus a baked-in Immersive Scaler.
• Translation — translate shape-key and material names.
• Lab Integration — detects sibling Unity AI Lab add-ons at runtime and surfaces their tools inline, with a selection handoff so they target the right objects. No hard dependency; the panel is hidden when no siblings are installed.

Installation

Cats Blender Expanded uses dual packaging from a single codebase:

• Blender 4.2+ (extension): install the extension zip via Edit → Preferences → Get Extensions → Install from Disk…, or drag-and-drop the zip into the Blender window. Blender reads blender_manifest.toml and auto-installs the bundled wheels.
• Blender 2.93 – 4.1 (legacy add-on): install the zip via Edit → Preferences → Add-ons → Install… and enable "Cats Blender Expanded". Blender reads the legacy bl_info block.

After enabling, open the 3D View sidebar (N) and select the CATS tab.

Blender version support

A single version-aware codebase targets a range of Blender releases through a compatibility layer (compat.py) rather than maintaining a separate branch per version (as upstream did).

Blender	Path	Status
2.93 – 3.6 LTS	Legacy bl_info	Supported (compat-layer hardened)
4.0 – 4.1	Legacy bl_info	Supported (compat-layer hardened)
4.2 LTS	Extension	Supported (compat-layer hardened)
5.x	Extension	Verified-working baseline

The hard floor is Blender 2.93; older versions are refused. Newer-than-tested Blender releases load with a console warning rather than a hard block, so new releases aren't locked out on day one. Newer Blender unlocks newer features; older Blender gracefully hides or falls back.

Differences from upstream

• Loads on Blender 5.1+ (upstream Neoneko 5.x hard-rejects anything but exactly 5.0.x) and, via the compat layer, back down to 2.93.
• Disabled the dangerous "faulty installation" cleaner — upstream deletes files from the parent directory (LICENSE, README, tools/, …) on a heuristic; it's a footgun in any non-standard layout. It is now a no-op.
• Own extension identity (id = cats_blender_expanded) so it coexists with stock CATS.
• Restored bake + decimation from the original CATS (the Neoneko fork had dropped them).
• Merged Avatar-Toolkit features — UV tools, VRM↔Unity converter, and Resonite loader/exporter.
• Lab Integration panel — detects sibling Unity AI Lab plugins at runtime and surfaces their tools inline (no hard dependency; hidden when absent).
• Updater repointed at the lab's self-hosted Forgejo release feed.

Part of the Unity AI Lab Blender suite

Cats Blender Expanded is standalone — it has no hard dependency on any other add-on and works on its own. When installed alongside its sibling Unity AI Lab add-ons, it detects them at runtime and surfaces their tools inline through its Lab Integration panel:

• Texturly — quick PBR materials, edge-trim, and bake-to-texture for VRChat worlds
• Deform Doctor — weight and deformation diagnostics + fixes
• Jiggle Lab — measured jiggle-physics rigging

Detection is runtime-only (no import, no dependency), so the panel simply stays hidden when a sibling isn't present. The suite is hosted on Unity AI Lab's self-hosted Forgejo:

git@git.unityailab.com:UnityAILab/CatsBlenderExpanded.git
https://git.unityailab.com/UnityAILab/CatsBlenderExpanded

Credits & attribution

Cats Blender Expanded is an expanded work building on the CATS Blender Plugin. Per the GPL, all upstream copyright and attribution is preserved. Full details are in CREDITS.md.

Source	Author / Maintainer	License	Role here
cats-blender-plugin (original, archived)	Absolute Quantum / GiveMeAllYourCats (2017)	MIT	Origin; source of restored bake + decimation
Cats-Blender-Plugin (Neoneko fork)	Team Neoneko (Yusarina)	GPL-3.0	Base codebase (Blender 5.x)
Cats-Blender-Plugin-Unofficial-	Yusarina	GPL-3.0	Mirror of the Neoneko fork
Avatar-Toolkit	Team Neoneko	GPL-3.0	Merged: Resonite, VRM↔Unity, UV tools

Original CATS code contributors (preserved): Hotox, Shotariya, Neitri, Kiraver, Jordo, Ruubick, 989onan, rurre, and the wider CATS community.

Bundled dependencies: MMD Tools; Immersive Scaler (MIT, baked in); the lz4 wheels (BSD-3-Clause) used for Resonite .animx; the Resonite AnimX loader and type tables (vendored from Avatar-Toolkit, GPL-3.0); a Google Translate helper; and Valve SMD reference skeletons.

License

GPL-3.0-or-later (SPDX:GPL-3.0-or-later). Because the base (Team Neoneko fork) and the merged Avatar-Toolkit features are GPL-3.0, and the original CATS was MIT (GPL-compatible), the combined work is licensed GPL-3.0-or-later. Full license text is in LICENSE.

Roadmap

Cats Blender Expanded is at version 0.1.0. Remaining work (see ROADMAP.md):

• Runtime verification on Blender 2.93, 3.6, and 4.2 LTS builds (5.x is the verified baseline; LTS support is currently hardened via the compat layer but not yet runtime-tested).
• Full bake multi-pass UI validation (normal, AO, metallic, emit, atlas, and decimation-integration passes).
• Tagged release on Forgejo with a prebuilt extension zip.