Animation

Skill XeldarAlz/everything-claude-unity/.claude/skills/systems/animation

Unity animation system — Animator controllers, layers, blend trees, state machine behaviors, root motion, animation events, Timeline.From its SKILL.md

Install

npx -y skills add XeldarAlz/everything-claude-unity --skill animation

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

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SKILL.md

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Animation System

Animator Controller

Parameters

// Cache hash IDs — NEVER use string version in Update
private static readonly int SpeedHash = Animator.StringToHash("Speed");
private static readonly int JumpHash = Animator.StringToHash("Jump");
private static readonly int IsGroundedHash = Animator.StringToHash("IsGrounded");
private static readonly int AttackHash = Animator.StringToHash("Attack");

private void Update()
{
    _animator.SetFloat(SpeedHash, _currentSpeed);
    _animator.SetBool(IsGroundedHash, _isGrounded);
}

// Triggers: fire once, auto-reset
public void Attack() => _animator.SetTrigger(AttackHash);

Transition Settings

Has Exit Time: animation finishes before transitioning (good for attacks, bad for instant response)
Fixed Duration: transition time in seconds vs normalized
Transition Duration: blend time (0 for instant, 0.1-0.25 for smooth)
Interruption Source: which transitions can interrupt this one

Layers

Base Layer: locomotion (walk, run, idle)
Upper Body Layer (Avatar Mask): aiming, attacks (overrides base)
Additive Layer: breathing, hit reactions (adds on top)

Blend Trees

1D: Speed parameter → walk/run blend 2D Simple Directional: X/Y input → directional movement (forward, back, strafe) 2D Freeform: more flexible placement of motion clips

State Machine Behaviors

public sealed class AttackStateBehavior : StateMachineBehaviour
{
    public override void OnStateEnter(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
    {
        // Enable hitbox
        animator.GetComponent<CombatSystem>().EnableHitbox();
    }

    public override void OnStateExit(Animator animator, AnimatorStateInfo stateInfo, int layerIndex)
    {
        // Disable hitbox
        animator.GetComponent<CombatSystem>().DisableHitbox();
    }
}

Root Motion

Enable Apply Root Motion on Animator
Override in OnAnimatorMove() for custom control:

private void OnAnimatorMove()
{
    // Use animation's root motion for position
    Vector3 deltaPosition = _animator.deltaPosition;
    transform.position += deltaPosition;

    // Use animation's rotation
    transform.rotation *= _animator.deltaRotation;
}

Animation Events

Call methods from specific frames in animation clips:

// Called from animation event on frame 12
public void OnFootstep()
{
    _audioSource.PlayOneShot(_footstepClip);
}

public void OnAttackHit()
{
    // Check hitbox collisions at this exact frame
}

IK (Inverse Kinematics)

private void OnAnimatorIK(int layerIndex)
{
    if (_lookTarget != null)
    {
        _animator.SetLookAtWeight(1f, 0.3f, 0.6f, 1f);
        _animator.SetLookAtPosition(_lookTarget.position);
    }

    // Foot IK for uneven terrain
    _animator.SetIKPositionWeight(AvatarIKGoal.LeftFoot, 1f);
    _animator.SetIKPosition(AvatarIKGoal.LeftFoot, _leftFootTarget);
}

Timeline Integration

Animation Track: play animation clips on any Animator
Custom Playable: create custom Timeline clips with PlayableAsset + PlayableBehaviour
Signal Track: fire events at specific times (similar to animation events but on Timeline)