Unity animation (animator and technical animator)

Expert animation work in Unity is ordering and measurement: which layer, constraint, transition or camera wins is decided by list order, and whether feet, aim and blends are right is decided by numbers taken from the clips. An agent without the Animator, Timeline or Scene windows builds everything from data (AnimatorController, TimelineAsset, Cinemachine and Rigging components), steps it deterministically, measures it, and looks at contact sheets. Target: Unity 6000.3.21f1, Cinemachine 3.1.7, Animation Rigging 1.4.1, Timeline 1.8.12. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-unity-expert (channels, review loop, 6.3 traps). Toolkit: scripts/ut_animation.py and C# jobs in scripts/AgentKit/Animation/ (namespace AgentKit.Animation), runtime code in scripts/Runtime/. Install with ut_animation.install(P).

Stance (the expert delta)

1. Order is behavior, everywhere. Lower Animator layers win (iHeartGameDev, W0eRZGS6dhQ [00:05:04]); additive stops at the first Override [00:09:46]; transitions are uninterruptible by default, and with Ordered Interruption only transitions above the running one cut in, ties to list order (Catherine Proulx, Unity blog; measured: her None, ordered, unordered and same-frame cases reproduce). An interruption blends from a frozen snapshot pose (measured: 0 deg/s bone motion on the interruption frame): keep interrupting transitions short [added inference]. Rig constraints solve depth-first, spine before head or hand (Code Monkey, luBBz5oeR4Q [00:06:20]; measured head error 0.0 vs 17.9 deg).
2. Blend-tree coordinates are gameplay units. Children at measured averageSpeed / averageAngularSpeed, not 0 / 0.5 / 1 (_J8RPIaO2Lc [00:16:30]); clamp the runtime parameter to the children's extents, or the edge pose holds while speed keeps rising [frame 00:13:38]. Script speed that disagrees with the clip slides the feet (Ketra Games, mNxEetKzc04 [00:00:32]; measured slide p50 0.19 vs 1.14 m/s).
3. Idle is its own state when its pose differs from the walk (no exit time on IsMoving), the tree starting at a slow walk (mNxEetKzc04 [00:08:54]). Idle at the tree origin is fine only for in-place clips driven by script speed (_J8RPIaO2Lc [00:04:24]).
4. Root motion is decided per clip and per axis (6.3 Manual): idle bakes rotation, Y and XZ; straight locomotion bakes rotation and Y; turns keep rotation; height-changing clips leave Y unbaked with Based Upon Feet, so blends do not float and a scripted jump does not add the clip's hip rise twice. Based Upon never causes drift: a baked axis has zero delta whatever it says; it only picks where the pose sits. Original keeps the file's facing and position (Ketra bakes Mixamo idles that way, no drift); Body Orientation re-centers mocap segments (measured over 30 s: both 0 m drift, Original faced 88 deg away and stood 2.43 m off; XZ unbaked drifted 0.246 m). One CharacterController.Move(deltaPosition + y) in OnAnimatorMove, never deltaPosition * Time.deltaTime [00:07:21]. Animator.gravityWeight is 1 on Y-baked clips, 0 on Y-unbaked ones, blended across transitions (Manual; measured, and 0 everywhere with root motion off).
5. Automate import from one reference, scoped to a folder (git-amend, V9_Z6hUOG_8): rig in OnPreprocessModel, clips in OnPreprocessAnimation, GetVersion() bumped on rule changes, never a reimport inside the callbacks. Roles come from file names or rules, never take names: every Mixamo take is "mixamo.com". Reference FBX sub-asset clips; a clip duplicated before the Humanoid switch keeps bone paths (BEZHVYk6Fa4 [00:12:03]; measured: it moved the humanoid 0.0 deg, the post-switch copy 40.1 deg). Copy From Other on a different hierarchy imports zero clips, reported only in the import log (observed). Translation DoF is off by default [00:02:21].
6. Masks make layers; reference poses make additive layers. An Override layer without a mask replaces the whole body; an additive clip only works over its authored base pose (W0eRZGS6dhQ [00:05:33], [00:09:57]). Masks at import drop fingers and IK goals a clip does not need (Manual, cost).
7. Cameras: one Brain, move targets, pick the rig by game type (Unity CM3.1 series). Smart Update plus Late Update blends first on jitter (Brain doc). Third Person Follow for over-the-shoulder; FreeLook plus Camera Offset plus Deoccluder fight (u0a1F6BlczE [00:02:41]). A procedural Position Control overrides animation; never parent one to a mover (XTVzs4B1d7I [00:03:10]). Cameras on opposite sides blend through the target: CylindricalPosition hint (measured: none 0.5 m and up dot 0.0, Cylindrical 5.02 m and 0.995, IgnoreTarget alone still 0.5 m) [00:13:32]. Deoccluder: Ignore Tag the player, glass on Transparent Layers; triggers never count (measured). Timeline overrides the Brain: priority is ignored until it stops (measured in Play mode).
8. Timeline: tracks for continuous actions, markers for instants, Signals when there is no payload (Ciro Continisio, gsEe0_o_934 [00:18:53]). A receiver gets every notification routed to it: type-check [frame 00:22:57]. Mixers run while scrubbing; spawn in OnGraphStart, destroy after [00:45:30].

Establish first

Platform and frame budget (performance hands off numbers); 3D skeletal vs 2D sprites (sprites go to scenario-unity-2d); rig type (Humanoid for retargeting and Mixamo, Generic when one skeleton and cost matter; Generic root motion works through the Root Node); root motion (player feet quality) vs in-place (NavMesh AI, tight speed control); content source: Mixamo (FBX for Unity, 30 fps, keyframe reduction none, same Mixamo character, Without Skin for clips; root motion: In Place off, Character Arm Space raised; mNxEetKzc04 [00:03:04], _J8RPIaO2Lc [00:01:24]), mocap takes to split, DCC; camera style; CM2 already in the project?; cutscene length and branching. Defaults: Humanoid, root motion for the player, CM 3.1.7, 30 fps Timeline, Input System.

Workflow

1. Packages. AnimPackages.Add with ["com.unity.cinemachine@3.1.7", "com.unity.animation.rigging@1.4.1"] (async, quit=False), then ua.install(P). GATE: ua.pinned_packages(P) all ok.
2. Import. ua.default_rules("Hero.fbx", files) -> AnimImport.ImportDrop (rules JSON, character first, masks, heals hierarchy mismatches). Split takes with AnimSampler.ClipProfile. GATE: audit counts.error == 0, avatar valid and human, every clip human_motion, no anim.role_fallback, an FBX outside the folder still Generic; AnimImport.AuditClips no anim.generic_duplicate.
3. Controller. Spec -> AnimControllerBuilder.Build (masks, layers, auto tree positions, transitions with interruption settings, hash class). GATE: counts.error == 0; positions equal measured speeds; ua.blend_tree_checks(tree, param_ranges) clean; urgent exits proven with ua.interruption_probe_spec-style events in SampleStates.
4. Sample and look. AnimSampler.SampleStates (Rebind, fixed Animator.Update; events, trace, per-sample clip/controller), LocomotionMetrics (clip for one clip alone). GATE: expected states; masked bones 0.000 deg; ground speed within 5 %; slide p50 < 0.25 m/s; idle 30 s drift < 1 cm; gravityWeight 0 through Y-unbaked clips (root motion on); sheet opened.
5. Rigging. AnimRigging.BuildAimRig then AuditRigs. GATE: head < 1 deg, hand < 1 cm, no rig.solve_order, frame looked at; one target moved, never rebound (rig.runtime_rebind); rig weight fades as the target goes behind (Htl7ysv10Qs [00:07:54], a Play-mode sample of Rig.weight).
6. Cameras. AnimCinemachine.SetupCameras (rigs, blend_hint, deoccluder), AuditCameras, CameraProbe (Manual Update; obstacles, occlusion linecast, series). GATE: live camera per event; ua.camera_probe_checks empty (no flip, no swing-through, no occluded or inside-geometry frames); ua.jitter_metrics reversal < 5 % [added]; audit 0 warn.
7. Timeline. AnimTimeline.BuildCutscene, SampleCutscene (scrub, frames), PlayCutscene (Play mode: markers, signals, live camera, handback), AuditTimeline. GATE: bindings; numeric blends; no root snap; markers and signals once; audit 0 warn; after the end the Brain's priority camera is live.
8. Proof and code. AnimProcedural.RootMotionPlay (one Move per frame), ua.scan_csharp(Assets) clean, numbers to scenario-unity-performance.

Procedures with full code and recorded results: references/procedures.md.

Numbers

Value	Relative to	Source
Clamp(0.1 x length, 0.1 s, 0.5 x length)	one-shot blend; blend out at length minus blend	fQzKJO-0dS8 [00:07:58]
0.7 aim / 0.3 look	chest weight under a hand aim / a head look	luBBz5oeR4Q [00:06:53]; Htl7ysv10Qs [00:08:59]
-100..100 deg	head aim limits, fade weight behind	Htl7ysv10Qs [00:06:58]
Min 1 s, Wait 0	State-Driven camera against flickering states	u0a1F6BlczE [00:09:32]
primary 2, fallback 1	ClearShot priorities	u0a1F6BlczE [00:14:53]
30 fps, keyframe reduction none	Mixamo download	_J8RPIaO2Lc [00:01:24]
T < sqrt(4 k2 + k1^2) - k1	second-order stability	KPoeNZZ6H4s [00:12:29]
1.08 / 3.51 m/s, -98 / +77 deg/s	Walk, Jog, turns of Unity's sample mocap	observed
0 m vs 0.246 m	30 s idle drift, XZ baked vs unbaked	observed
0.5 m vs 5.02 m	closest camera approach, no hint vs Cylindrical	observed

Quality gates

• Measurable: import audit and AuditClips clean; controller audit; mask check; speed within 5 %; slide p50; idle drift; rig errors; camera probe checks and jitter; Timeline bindings, events, audit; one Move per frame; C# scan.
• Visual: a contact sheet per stage judged with references/critique.md (T-pose, feet in the floor, arms through the body, snaps, camera flips, framing); ut_review flags none.

Common mistakes

Mistake	What it looks like	Fix
sampling with Culling Mode not Always Animate	batch captures show the bind pose	the sampler forces Always Animate (observed)
flags chosen from take names	every Mixamo clip gets the same loop and bake flags	roles from file names or rules; rename clips
unscoped import processor	every FBX in the project turns Humanoid	a rules file or an assetPath guard; ua.scan_csharp
jump clip with root Y baked	floats in blends; hip rise added to the scripted jump	Y unbaked, Based Upon Feet
.anim duplicated before the Humanoid switch	the clip plays on no humanoid	re-duplicate after, or reference the FBX clip
Copy From Other on a different hierarchy	FBX imports with no clips, console silent	read the import log; own avatar per file (observed)
Based Upon blamed for drift	idle slides away over loops	bake XZ; Based Upon only places the pose
parameter past the tree extents	speed rises, animation does not	clamp to the children
head constraint above the chest	head misses its target	body first in sibling order
cameras on opposite sides, no hint	blend dives through the head and flips	CylindricalPosition on both
glass or triggers treated as walls	camera jumps in front of windows	Transparent Layers; triggers are ignored
priority raised during a cutscene	nothing changes until it ends	Timeline owns the Brain
Priority set from an editor script	Brain keeps the old camera	cam.Prioritize() (observed)
scrubbing to test markers or the handback	no marker fires; last shot stays live	PlayCutscene (observed)
OnNotify without a type check	reacts to every marker	if (n is MyMarker m)
Optimize Game Objects applied early	scene instance vanishes	apply late, before shipping (BEZHVYk6Fa4 [00:07:22])

More agent traps (GUID moves on archive, one class per file, ?? on Unity objects, Play-mode reads): references/procedures.md.

Handoffs

• Receives: character FBX and clips from scenario-blender-expert, scenario-maya-expert or scenario-3d; input actions from scenario-unity-architecture; locomotion speeds, NavMesh agents and gameplay events from scenario-unity-gameplay; import-pipeline conventions from scenario-unity-pipeline-automation.
• Delivers: to scenario-unity-gameplay the controller, parameter contract (Speed m/s, TurnRate deg/s, IsMoving, Jump), hash class, root-motion mover (vertical source); to scenario-unity-rendering-lighting camera cuts (reset temporal effects on Camera Cut) and Timeline light tracks; to scenario-unity-performance Animator counts, culling modes, import masks, Optimize Game Objects late; to scenario-unity-vfx Signals and Activation tracks. Packet: project, jobs, audit JSON, sheets, metrics, Verified and Assumed lists.

Unity 6.3 notes

• The 6000.3.21f1 manifest lists Cinemachine 2.10.7; a bare Client.Add resolved 3.1.7 (observed): pin anyway. CM3 is Unity.Cinemachine, CinemachineCamera plus components; CM2 upgrade = retype to CinemachineVirtualCameraBase, then Upgrade Entire Project (no Undo). In 6.6 CM3, Timeline and Animation Rigging become core.
• Timeline 1.8: editorSettings.frameRate. 6.3 adds Animator.ResetControllerState. Obsolete ModelImporter members become errors in 6.5.
• Templates run the Input System only; entering Play mode reloads the domain (Play-mode jobs switch it off for the run).

References

• references/expert-notes.md: principles and judgment by expert, with source and timestamp.
• references/procedures.md: every job with args, the Unity calls behind it, live test and result.
• references/critique.md: the rubric to judge rigs, blends, feet, cameras and cutscenes.
• references/gui-paths.md: windows and menus for the same work.
• references/sources.md: every source, credential, URL, best timestamps, revision history.