Unity Animation

Overview

Unity animation systems include Mecanim Animator, Animancer (3rd party), and low-level Playables API. This skill covers common patterns and optimizations.

When to Use

• Character animations
• UI animations
• Procedural animation
• Animation blending
• State-driven animation

Animancer Patterns

Basic State Playing

using Animancer;

public class CharacterAnimator : MonoBehaviour
{
    [SerializeField] private AnimancerComponent _animancer;
    [SerializeField] private AnimationClip _idle;
    [SerializeField] private AnimationClip _run;
    [SerializeField] private AnimationClip _attack;
    
    public void PlayIdle()
    {
        _animancer.Play(_idle);
    }
    
    public void PlayRun()
    {
        _animancer.Play(_run, 0.25f); // With fade
    }
    
    public void PlayAttack(Action onComplete)
    {
        var state = _animancer.Play(_attack);
        state.Events.OnEnd = () =>
        {
            PlayIdle();
            onComplete?.Invoke();
        };
    }
}

Animation State Machine

public class AnimationStateMachine : MonoBehaviour
{
    [SerializeField] private AnimancerComponent _animancer;
    
    private readonly Dictionary<string, ClipTransition> _states = new();
    private string _currentState;
    
    public void RegisterState(string name, ClipTransition clip)
    {
        _states[name] = clip;
    }
    
    public void Play(string stateName, float fadeDuration = 0.25f)
    {
        if (_currentState == stateName) return;
        
        if (_states.TryGetValue(stateName, out var clip))
        {
            _animancer.Play(clip, fadeDuration);
            _currentState = stateName;
        }
    }
    
    public bool IsPlaying(string stateName) => _currentState == stateName;
}

Blended Movement

public class LocomotionAnimator : MonoBehaviour
{
    [SerializeField] private AnimancerComponent _animancer;
    [SerializeField] private LinearMixerTransition _locomotion;
    
    private LinearMixerState _locomotionState;
    
    private void Awake()
    {
        _locomotionState = (LinearMixerState)_animancer.Play(_locomotion);
    }
    
    public void SetSpeed(float normalizedSpeed)
    {
        // Blend between idle (0), walk (0.5), run (1)
        _locomotionState.Parameter = normalizedSpeed;
    }
}

Layer-Based Animation

public class LayeredAnimator : MonoBehaviour
{
    [SerializeField] private AnimancerComponent _animancer;
    
    private const int BaseLayer = 0;
    private const int UpperBodyLayer = 1;
    
    private void Start()
    {
        // Setup layers
        _animancer.Layers.SetCapacity(2);
        
        // Upper body layer only affects specific bones
        _animancer.Layers[UpperBodyLayer].SetMask(CreateUpperBodyMask());
    }
    
    public void PlayUpperBodyAction(AnimationClip clip)
    {
        _animancer.Layers[UpperBodyLayer].Play(clip);
    }
    
    public void StopUpperBodyLayer(float fadeDuration = 0.2f)
    {
        _animancer.Layers[UpperBodyLayer].StartFade(0, fadeDuration);
    }
    
    private AvatarMask CreateUpperBodyMask()
    {
        // Create or load avatar mask for upper body
        var mask = new AvatarMask();
        // Configure mask...
        return mask;
    }
}

Mecanim Patterns

Safe Parameter Setting

public class SafeAnimator : MonoBehaviour
{
    private Animator _animator;
    private readonly Dictionary<string, int> _parameterHashes = new();
    private readonly HashSet<int> _validParameters = new();
    
    private void Awake()
    {
        _animator = GetComponent<Animator>();
        CacheParameters();
    }
    
    private void CacheParameters()
    {
        foreach (var param in _animator.parameters)
        {
            _parameterHashes[param.name] = param.nameHash;
            _validParameters.Add(param.nameHash);
        }
    }
    
    public void SetFloat(string name, float value)
    {
        if (TryGetHash(name, out int hash))
        {
            _animator.SetFloat(hash, value);
        }
    }
    
    public void SetBool(string name, bool value)
    {
        if (TryGetHash(name, out int hash))
        {
            _animator.SetBool(hash, value);
        }
    }
    
    public void SetTrigger(string name)
    {
        if (TryGetHash(name, out int hash))
        {
            _animator.SetTrigger(hash);
        }
    }
    
    private bool TryGetHash(string name, out int hash)
    {
        if (!_parameterHashes.TryGetValue(name, out hash))
        {
            hash = Animator.StringToHash(name);
            _parameterHashes[name] = hash;
        }
        
        return _validParameters.Contains(hash);
    }
}

State Checking

public static class AnimatorExtensions
{
    public static bool IsInState(this Animator animator, string stateName, int layer = 0)
    {
        var stateInfo = animator.GetCurrentAnimatorStateInfo(layer);
        return stateInfo.IsName(stateName);
    }
    
    public static bool IsTransitioning(this Animator animator, int layer = 0)
    {
        return animator.IsInTransition(layer);
    }
    
    public static float GetNormalizedTime(this Animator animator, int layer = 0)
    {
        var stateInfo = animator.GetCurrentAnimatorStateInfo(layer);
        return stateInfo.normalizedTime % 1f;
    }
    
    public static bool IsAnimationComplete(this Animator animator, int layer = 0)
    {
        var stateInfo = animator.GetCurrentAnimatorStateInfo(layer);
        return !stateInfo.loop && stateInfo.normalizedTime >= 1f;
    }
}

Animation Events

Safe Event Handling

public class AnimationEventReceiver : MonoBehaviour
{
    public event Action<string> OnAnimationEvent;
    
    private readonly Dictionary<string, Action> _eventHandlers = new();
    
    public void RegisterHandler(string eventName, Action handler)
    {
        _eventHandlers[eventName] = handler;
    }
    
    public void UnregisterHandler(string eventName)
    {
        _eventHandlers.Remove(eventName);
    }
    
    // Called by animation events
    public void OnAnimEvent(string eventName)
    {
        if (_eventHandlers.TryGetValue(eventName, out var handler))
        {
            handler?.Invoke();
        }
        
        OnAnimationEvent?.Invoke(eventName);
    }
    
    // Common events
    public void FootstepLeft() => OnAnimEvent("FootstepLeft");
    public void FootstepRight() => OnAnimEvent("FootstepRight");
    public void AttackHit() => OnAnimEvent("AttackHit");
    public void AttackEnd() => OnAnimEvent("AttackEnd");
}

Async Animation Waiting

public static class AnimationAsyncExtensions
{
    public static async UniTask WaitForStateComplete(
        this Animator animator, 
        string stateName, 
        int layer = 0,
        CancellationToken ct = default)
    {
        // Wait for state to start
        while (!animator.IsInState(stateName, layer) && !ct.IsCancellationRequested)
        {
            await UniTask.Yield(ct);
        }
        
        // Wait for state to complete
        while (!animator.IsAnimationComplete(layer) && !ct.IsCancellationRequested)
        {
            await UniTask.Yield(ct);
        }
    }
    
    public static async UniTask PlayAndWait(
        this AnimancerComponent animancer,
        AnimationClip clip,
        CancellationToken ct = default)
    {
        var state = animancer.Play(clip);
        
        await UniTask.WaitUntil(
            () => state.NormalizedTime >= 1f || !state.IsPlaying,
            cancellationToken: ct
        );
    }
}

Root Motion

Controlled Root Motion

public class RootMotionController : MonoBehaviour
{
    private Animator _animator;
    private CharacterController _controller;
    
    [SerializeField] private bool _useRootPosition = true;
    [SerializeField] private bool _useRootRotation = true;
    [SerializeField] private float _rootMotionScale = 1f;
    
    private void Awake()
    {
        _animator = GetComponent<Animator>();
        _controller = GetComponent<CharacterController>();
    }
    
    private void OnAnimatorMove()
    {
        if (_useRootPosition)
        {
            Vector3 deltaPosition = _animator.deltaPosition * _rootMotionScale;
            _controller.Move(deltaPosition);
        }
        
        if (_useRootRotation)
        {
            transform.rotation *= _animator.deltaRotation;
        }
    }
    
    public void SetRootMotionEnabled(bool position, bool rotation)
    {
        _useRootPosition = position;
        _useRootRotation = rotation;
    }
}

Performance Optimization

Animator Culling

public class AnimatorOptimizer : MonoBehaviour
{
    private Animator _animator;
    
    private void Awake()
    {
        _animator = GetComponent<Animator>();
        
        // Configure culling based on use case
        if (IsMainCharacter())
        {
            _animator.cullingMode = AnimatorCullingMode.AlwaysAnimate;
        }
        else
        {
            _animator.cullingMode = AnimatorCullingMode.CullUpdateTransforms;
        }
    }
    
    private bool IsMainCharacter()
    {
        return CompareTag("Player");
    }
}

LOD Animation

public class AnimationLOD : MonoBehaviour
{
    private Animator _animator;
    private float _lastUpdateTime;
    
    [SerializeField] private float _nearDistance = 10f;
    [SerializeField] private float _farDistance = 30f;
    
    private Camera _mainCamera;
    
    private void Start()
    {
        _animator = GetComponent<Animator>();
        _mainCamera = Camera.main;
    }
    
    private void LateUpdate()
    {
        float distance = Vector3.Distance(transform.position, _mainCamera.transform.position);
        
        if (distance > _farDistance)
        {
            // Very far - minimal updates
            _animator.updateMode = AnimatorUpdateMode.Normal;
            _animator.speed = 0.5f; // Slow motion illusion from distance
        }
        else if (distance > _nearDistance)
        {
            // Medium distance
            _animator.updateMode = AnimatorUpdateMode.Normal;
            _animator.speed = 1f;
        }
        else
        {
            // Close - full quality
            _animator.updateMode = AnimatorUpdateMode.AnimatePhysics;
            _animator.speed = 1f;
        }
    }
}

Disable When Offscreen

public class AnimatorVisibilityOptimizer : MonoBehaviour
{
    private Animator _animator;
    private Renderer _renderer;
    
    private void Awake()
    {
        _animator = GetComponent<Animator>();
        _renderer = GetComponentInChildren<Renderer>();
    }
    
    private void OnBecameInvisible()
    {
        if (_animator != null)
        {
            _animator.enabled = false;
        }
    }
    
    private void OnBecameVisible()
    {
        if (_animator != null)
        {
            _animator.enabled = true;
        }
    }
}

Best Practices

1. Use Animancer for flexibility over Mecanim
2. Cache parameter hashes - Avoid string lookups
3. Set culling modes appropriately
4. Use animation events sparingly
5. Pool animated objects - Avoid Instantiate
6. Reduce bone count for mobile
7. Use LOD for distant characters
8. Disable when invisible - Save CPU
9. Bake animations when possible
10. Profile animation cost - Major performance factor

Troubleshooting

Issue	Solution
Animation not playing	Check Animator enabled, state exists
Jerky transitions	Adjust fade duration
Root motion drift	Verify Apply Root Motion setting
Parameter not found	Cache and validate parameters
Performance issues	Enable culling, reduce bones
Stuck in state	Check exit conditions, transitions