Full-stack-skills threejs-animation

three.js keyframe animation system: AnimationMixer, AnimationClip, AnimationAction, KeyframeTrack variants, PropertyBinding, PropertyMixer, AnimationObjectGroup, AnimationUtils; mixing and crossfading clips, loop modes, timeScale, weight; addon AnimationClipCreator and CCDIKSolver for procedural rigs. Use when playing glTF clips, blending actions, or authoring procedural tracks; for skin deformation rigging on meshes see threejs-objects; for math interpolants without clips see threejs-math only when not tied to AnimationMixer.

install

source · Clone the upstream repo

git clone https://github.com/partme-ai/full-stack-skills

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/partme-ai/full-stack-skills "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/threejs-skills/threejs-animation" ~/.claude/skills/partme-ai-full-stack-skills-threejs-animation && rm -rf "$T"

manifest: skills/threejs-skills/threejs-animation/SKILL.md

When to use this skill

ALWAYS use this skill when the user mentions:

```
AnimationMixer.update
```
,
```
AnimationAction
```
play/pause/stop, crossfade, synchronized clips
```
AnimationClip
```
from glTF or
```
AnimationClipCreator
```
, retargeting caveats at API level
Keyframe tracks: position/rotation/scale/color tracks, boolean/string tracks where applicable
IK:
```
CCDIKSolver
```
/
```
CCDIKHelper
```
from addons

IMPORTANT: animation vs objects

threejs-animation = time evaluation and tracks.
threejs-objects =
```
SkinnedMesh
```
/
```
Skeleton
```
attachment, bind pose—mesh side.

Trigger phrases include:

"AnimationMixer", "AnimationAction", "AnimationClip", "crossFade", "KeyframeTrack"
"动画混合", "骨骼动画", "剪辑", "淡入淡出"

How to use this skill

Collect clips from
```
gltf.animations
```
or create with utilities /
```
AnimationClipCreator
```
.
Create mixer bound to root object (often
```
scene
```
or rig root).
Create actions per clip via
```
mixer.clipAction(clip)
```
; configure loop mode (
```
LoopOnce
```
,
```
LoopRepeat
```
,
```
LoopPingPong
```
).
Per frame: compute delta seconds (use
```
Clock
```
from core—documented under Core in docs index), call
```
mixer.update(delta)
```
.
Blending: adjust
```
weight
```
,
```
crossFadeTo
```
,
```
enabled
```
flags; watch for additive vs full replacement semantics per docs.
PropertyBinding: understand path strings targeting bones/morphs—errors often from wrong object names.
IK addon: attach solver after base animation if using CCD IK from examples.

See examples/workflow-mixer-action.md.

Doc map (official)

Docs section	Representative links
Animation (index)	https://threejs.org/docs/#Animation
Action	https://threejs.org/docs/AnimationAction.html
Mixer	https://threejs.org/docs/AnimationMixer.html
Clip	https://threejs.org/docs/AnimationClip.html
Tracks	https://threejs.org/docs/KeyframeTrack.html

More: references/official-sections.md.

Scope

In scope: Core Animation module, keyframe pipeline, listed addons for clip creation and IK.
Out of scope: DCC export best practices; physics ragdoll; audio sync (link conceptually only).

Common pitfalls and best practices

Forgetting
```
mixer.update
```
freezes animation; double
```
update
```
per frame speeds up.
Mixing clips with incompatible hierarchies causes violent pops—validate bind pose.
Root motion must be handled in game logic if not baked—document explicitly.
Large track counts cost CPU—strip unused tracks in preprocessing when possible.

Documentation and version

Behavior of

AnimationMixer

, tracks, and glTF animation import can change between three.js majors. Treat the Animation section of the docs index as authoritative for the user’s installed version; when upgrading, check the three.js repository release notes and migration notes for renamed properties or loader output.

Agent response checklist

When answering under this skill, prefer responses that:

Cite the exact class (
```
AnimationMixer
```
,
```
AnimationAction
```
, etc.) or addon (
```
CCDIKSolver
```
) from the official docs.
Include at least one
```
https://threejs.org/docs/...
```
link (e.g. AnimationAction).
Relate clips to
```
SkinnedMesh
```
/ skeleton via threejs-objects when deformation is involved.
Mention
```
mixer.update(delta)
```
and a stable time source (
```
Clock
```
) explicitly.
Reference official examples by name only (no full file paste).

References

Keywords

English: animationmixer, animationaction, animationclip, keyframetrack, crossfade, skinning, propertybinding, three.js

中文： 动画混合、AnimationMixer、AnimationAction、关键帧、骨骼动画、剪辑、淡入淡出、three.js