Unity Animation (Animator / Mecanim)

Control animation state with Unity 6's

Animator

and Animator Controllers: parameters, transitions, blend trees, layers, and humanoid IK. Targets Unity 6 (6000.0 LTS).

When to use

Use when connecting animation clips into a state machine, driving them from script via parameters, blending locomotion (idle→walk→run), layering an upper-body action over movement, or adding foot/hand IK on a humanoid rig.
Use when the project has
```
*.controller
```
(Animator Controller) and
```
*.anim
```
assets, or a rigged model with an Avatar.

When not to use: simple non-skeletal value tweens (UI fades, position lerps) are better done with a tween/coroutine — see

unity-csharp-scripting

. Timeline cutscenes are a separate tool. 2D sprite frame animation also uses the Animator but with sprite keyframes.

Core workflow

Add an
Animator
to the model and assign an Animator Controller; for a humanoid model, set its rig to Humanoid so it has an Avatar (enables retargeting and IK).
Define parameters on the controller —
```
Float
```
(Speed),
```
Bool
```
(IsGrounded),
```
Int
```
,
```
Trigger
```
(Jump) — and states with transitions whose conditions read those parameters.
Set parameters from script, never poke states directly:
```
SetFloat
```
,
```
SetBool
```
,
```
SetInteger
```
,
```
SetTrigger
```
. The state machine resolves transitions for you.
Blend continuous motion with a Blend Tree (one
```
Float
```
like Speed drives idle↔walk↔run) instead of many discrete states + transitions.
Layer additive/override motion (e.g. an upper-body "aim" layer with an Avatar Mask) and control its
```
layerWeight
```
.
Verify in the Animator window during Play mode — the live state highlights and parameter values update, so you can see exactly which transition fired (or didn't).

Patterns

1. Drive locomotion + a one-shot action from script

csharp

using UnityEngine;

[RequireComponent(typeof(Animator))]
public class CharacterAnim : MonoBehaviour
{
    private Animator _anim;
    // Cache parameter hashes — faster and typo-proof vs string lookups every frame.
    private static readonly int Speed     = Animator.StringToHash("Speed");
    private static readonly int IsGrounded= Animator.StringToHash("IsGrounded");
    private static readonly int Jump      = Animator.StringToHash("Jump");

    private void Awake() => _anim = GetComponent<Animator>();

    public void Tick(float planarSpeed, bool grounded)
    {
        _anim.SetFloat(Speed, planarSpeed);     // drives a 1D blend tree (idle/walk/run)
        _anim.SetBool(IsGrounded, grounded);    // gates a falling/landing transition
    }

    public void DoJump() => _anim.SetTrigger(Jump);  // fire-and-forget; auto-resets after use
}

2. Smooth a noisy input into a blend parameter

csharp

// dampTime smooths Speed so the blend tree doesn't snap; great for analog sticks.
_anim.SetFloat(Speed, targetSpeed, 0.1f /* dampTime */, Time.deltaTime);

3. Play / cross-fade a state directly (bypassing parameter conditions)

csharp

// Useful for hit reactions where you want an immediate, explicit transition.
_anim.CrossFade("Hit", 0.1f);                    // blend over 0.1s normalized
// Or jump instantly:  _anim.Play("Hit");

4. Wait until the current state finishes

csharp

private System.Collections.IEnumerator AfterAttack()
{
    var info = _anim.GetCurrentAnimatorStateInfo(0);   // layer 0
    yield return new WaitForSeconds(info.length);      // approximate clip length
    // ...follow-up logic
}

Pitfalls

SetTrigger
missed or "sticks" — triggers are consumed by the next satisfied transition and auto-reset; if no transition consumes it, it can fire later unexpectedly. Use
```
ResetTrigger
```
to clear, or prefer a
```
Bool
```
when the condition is a sustained state.
String parameter typos fail silently — a misspelled name just does nothing. Use
```
Animator.StringToHash
```
and cache the int hashes.
Transition feels laggy —
```
Has Exit Time
```
makes the transition wait for the clip to reach a normalized time. Uncheck it for responsive, condition-driven transitions (jump, hit).
Character slides or won't move —
```
Apply Root Motion
```
is on but your code also moves the transform (or vice versa). Decide: root motion or scripted movement, not both.
Upper-body layer overrides the whole body — set the layer's Blend mode (Override vs Additive), assign an Avatar Mask, and tune
```
layerWeight
```
(0–1).
IK does nothing — IK only applies inside
```
OnAnimatorIK
```
, requires "IK Pass" enabled on the layer, and needs a Humanoid Avatar.

References

For blend trees (1D vs 2D Freeform/Directional), animation layers + Avatar Masks, and humanoid IK (
```
OnAnimatorIK
```
,
```
SetIKPositionWeight
```
,
```
SetIKPosition
```
, look-at), read
```
references/blend-trees-and-ik.md
```
.
Primary docs: Unity Manual "Animation" section and
```
ScriptReference/Animator
```
.

Related skills

```
unity-csharp-scripting
```
— the MonoBehaviour and coroutine timing used above.
```
unity-physics
```
— moving the body that the animation visualises.
```
game-ai
```
— deciding when to play which animation state.

unity-animation

NPX Install

Tags

SKILL.md Content

Unity Animation (Animator / Mecanim)

When to use

Core workflow

Patterns

1. Drive locomotion + a one-shot action from script

2. Smooth a noisy input into a blend parameter

3. Play / cross-fade a state directly (bypassing parameter conditions)

4. Wait until the current state finishes

Pitfalls

References

Related skills