Unity Playables API

Unity Playables API

Retrieval Sources

Docs root: /media/artiq/FRESH_DRIVE/Books/Unity6/Documentation/en/

All paths below were verified to exist on disk (ls/find against Manual/ and ScriptReference/; ScriptReference/ alone holds 296 files matching *Playable*, Manual/ holds a full 13-page Playables API chapter under Manual/Playables.html).

Key Guidelines

PlayableGraph Fundamentals (creation/destruction/lifecycle)

A PlayableGraph is a lightweight C# struct handle to a native graph of time-synchronized nodes (Manual/Playables-Graph.html). Unlike the Animator's state-machine graph, which only understands animation, a PlayableGraph is data-agnostic — the same graph machinery drives animation, audio, or arbitrary scripted logic depending on what kind of PlayableOutput and Playable nodes you attach to it. You create one with the static PlayableGraph.Create() (optionally passing a name used only by editor tooling), and every playable/output you subsequently create must pass that same graph instance as its first Create() argument — the graph owns the native lifetime of everything built through it. Because Playable, PlayableOutput, and their subtypes are C# structs rather than classes (Manual/Playables-Graph.html calls this out explicitly), creating them allocates no managed garbage — but the native side they wrap is real unmanaged memory that the C# garbage collector knows nothing about. That's why PlayableGraph.Destroy() is mandatory: it schedules destruction of the graph and everything it owns (all playables, all outputs) for later in the same frame; skip it and Unity logs an error and the native graph leaks for the life of the domain. The idiomatic place to pair Create()/Destroy() is Start()/OnDisable() on the owning MonoBehaviour, mirroring every worked example in Manual/playables-ex-*.html.

using UnityEngine;
using UnityEngine.Playables;
using UnityEngine.Animations;

[RequireComponent(typeof(Animator))]
public class MinimalGraphOwner : MonoBehaviour
{
    public AnimationClip clip;
    PlayableGraph graph;

    void Start()
    {
        // The graph owns every playable/output created from it below.
        graph = PlayableGraph.Create("MinimalGraphOwner");
        graph.SetTimeUpdateMode(DirectorUpdateMode.GameTime);

        var output = AnimationPlayableOutput.Create(graph, "Animation", GetComponent<Animator>());
        var clipPlayable = AnimationClipPlayable.Create(graph, clip);
        output.SetSourcePlayable(clipPlayable);

        graph.Play(); // starts advancing time; without this the graph sits frozen at t=0
    }

    void OnDisable()
    {
        // Mandatory: without this the native graph and every node/output it owns leaks.
        if (graph.IsValid())
            graph.Destroy();
    }
}

graph.Play()/graph.Stop() control whether the graph's clock advances at all; graph.IsPlaying() and graph.IsDone() let you query that state, and graph.IsValid() (ScriptReference/Playables.PlayableGraph.IsValid.html) tells you whether the graph has been created and not yet destroyed — check it before touching a graph reference held across frames, since using a destroyed graph throws. For advanced tooling, UnityEditor.Playables.Utility.GetAllGraphs() (ScriptReference/Playables.Utility.html) enumerates every currently-alive PlayableGraph in the editor process, and its graphCreated/destroyingGraph events let editor code track graph lifetime globally — useful for building custom debugging/visualization tools now that the official PlayableGraph Visualizer package is discontinued.

Playable Outputs (Animation / Audio)

A PlayableOutput is the other endpoint of a graph — it defines where the result of evaluating a branch of playables actually goes (Manual/Playables-Graph.html). Like Playable, output types are structs, and non-abstract output types expose a static Create(graph, ...) method that the owning graph parents. An output only does something once you link it to a playable via SetSourcePlayable() (a PlayableOutputExtensions method, ScriptReference/Playables.PlayableOutputExtensions.html) — an output with no source playable evaluates to nothing every frame, which is one of the most common "the graph runs but nothing happens" bugs. The two output types you'll reach for constantly are AnimationPlayableOutput (targets an Animator component, ScriptReference/Animations.AnimationPlayableOutput.html) and AudioPlayableOutput (targets audio playback, ScriptReference/Audio.AudioPlayableOutput.html); a single graph can hold multiple outputs of different types simultaneously, each fed by its own (or a shared) playable subtree — Manual/playables-ex-different-outputs.html builds exactly this, one graph driving both an animated GameObject and an AudioClip at once.

using UnityEngine;
using UnityEngine.Animations;
using UnityEngine.Audio;
using UnityEngine.Playables;

[RequireComponent(typeof(Animator))]
[RequireComponent(typeof(AudioSource))]
public class DifferentOutputs : MonoBehaviour
{
    public AnimationClip animationClip;
    public AudioClip audioClip;
    PlayableGraph graph;

    void Start()
    {
        graph = PlayableGraph.Create("DifferentOutputs");

        var animationOutput = AnimationPlayableOutput.Create(graph, "Animation", GetComponent<Animator>());
        var audioOutput = AudioPlayableOutput.Create(graph, "Audio", GetComponent<AudioSource>());

        var animationClipPlayable = AnimationClipPlayable.Create(graph, animationClip);
        var audioClipPlayable = AudioClipPlayable.Create(graph, audioClip, true);

        animationOutput.SetSourcePlayable(animationClipPlayable);
        audioOutput.SetSourcePlayable(audioClipPlayable);

        graph.Play();
    }

    void OnDisable() => graph.Destroy();
}

Source: Manual/playables-ex-different-outputs.html.

For output types with no built-in scene target — when a playable needs to drive arbitrary gameplay code rather than an Animator or AudioSource — use ScriptPlayableOutput (ScriptReference/Playables.ScriptPlayableOutput.html). It's a "pure" output: connect a ScriptPlayable<T> as its source and every ProcessFrame call on that behaviour becomes your hook for doing whatever work the output is meant to represent. Outputs can also carry a weight (PlayableOutputExtensions.SetWeight/GetWeight) and a reference object (SetReferenceObject, used by Timeline to associate an output with the authoring track asset), and can register INotificationReceivers (AddNotificationReceiver) to receive one-shot events pushed through PushNotification — this is the mechanism Timeline's Signal tracks build on.

Writing a Custom PlayableBehaviour

PlayableBehaviour (ScriptReference/Playables.PlayableBehaviour.html, Manual/Playables-ScriptPlayable.html) is the base class every custom playable inherits from. On its own a PlayableBehaviour isn't a node in the graph — you wrap it in a ScriptPlayable<T> (ScriptReference/Playables.ScriptPlayable_1.html), which is the actual IPlayable struct that gets connected like any other node. Two creation patterns exist: ScriptPlayable<T>.Create(graph) builds a fresh default-constructed behaviour, while ScriptPlayable<T>.Create(graph, existingInstance) clones existingInstance and assigns the clone into the graph — useful when you want to pre-configure per-instance fields (e.g. from the Inspector) before the behaviour enters the graph. Retrieve the live behaviour back out of the wrapper with scriptPlayable.GetBehaviour().

PlayableBehaviour exposes a lifecycle of overridable callbacks, and getting their order and purpose right matters:

• OnPlayableCreate(Playable) / OnPlayableDestroy(Playable) — fire once each, tied to the owning Playable node's own creation/destruction (ScriptReference/Playables.PlayableBehaviour.OnPlayableCreate.html, ...OnPlayableDestroy.html), independent of whether the graph is playing.
• OnGraphStart(Playable) / OnGraphStop(Playable) — fire once each per graph play session: OnGraphStart when the owning graph starts playing or is first evaluated, OnGraphStop when it stops; the docs guarantee every OnGraphStart is paired with exactly one OnGraphStop, including a stop call before destruction of a manually-evaluated graph (ScriptReference/Playables.PlayableBehaviour.OnGraphStart.html, ...OnGraphStop.html). Use these for graph-scoped setup/teardown (allocating a resource once for the whole playback session), not per-frame work.
• OnBehaviourPlay(Playable, FrameData) / OnBehaviourPause(Playable, FrameData) — fire on transitions of this playable's effective play state, distinct from the graph-level start/stop above (ScriptReference/Playables.PlayableBehaviour.OnBehaviourPlay.html, ...OnBehaviourPause.html); OnBehaviourPause also fires if the whole graph stops while this playable was still marked playing.
• PrepareFrame(Playable, FrameData) — called every evaluated frame; this is where you should make topological changes (reconnecting inputs), change input weights, or otherwise change state that affects how the graph is structured or blended for this frame (ScriptReference/Playables.PlayableBehaviour.PrepareFrame.html). This is the phase the built-in queue example (below) uses to decide which clip is "current" and adjust mixer weights accordingly.
• ProcessFrame(Playable, FrameData, object playerData) — called every frame the playable is playing and connected (directly or indirectly) to a ScriptPlayableOutput; this is where the actual output-producing work happens, and playerData is the output's user data set via SetUserData (ScriptReference/Playables.PlayableBehaviour.ProcessFrame.html).
• OnBehaviourDelay / PrepareData — tied to the now-obsolete PlayState.Delayed state; Unity's own docs say to implement delay behavior via a custom ScriptPlayable instead of relying on this path (ScriptReference/Playables.PlayableBehaviour.OnBehaviourDelay.html).

The canonical worked example — a custom playable that cycles through a list of animation clips, one at a time, adjusting a mixer's weights each frame — comes straight from Manual/playables-ex-custom-playable.html:

using UnityEngine;
using UnityEngine.Animations;
using UnityEngine.Playables;

public class PlayQueuePlayable : PlayableBehaviour
{
    int m_CurrentClipIndex = -1;
    float m_TimeToNextClip;
    Playable mixer;

    public void Initialize(AnimationClip[] clipsToPlay, Playable owner, PlayableGraph graph)
    {
        owner.SetInputCount(1);
        mixer = AnimationMixerPlayable.Create(graph, clipsToPlay.Length);
        graph.Connect(mixer, 0, owner, 0);
        owner.SetInputWeight(0, 1);

        for (int i = 0; i < mixer.GetInputCount(); ++i)
        {
            graph.Connect(AnimationClipPlayable.Create(graph, clipsToPlay[i]), 0, mixer, i);
            mixer.SetInputWeight(i, 1.0f);
        }
    }

    public override void PrepareFrame(Playable owner, FrameData info)
    {
        if (mixer.GetInputCount() == 0) return;

        m_TimeToNextClip -= (float)info.deltaTime; // use FrameData.deltaTime, not Time.deltaTime
        if (m_TimeToNextClip <= 0.0f)
        {
            m_CurrentClipIndex++;
            if (m_CurrentClipIndex >= mixer.GetInputCount())
                m_CurrentClipIndex = 0;

            var currentClip = (AnimationClipPlayable)mixer.GetInput(m_CurrentClipIndex);
            currentClip.SetTime(0); // restart the newly-active clip at its beginning
            m_TimeToNextClip = currentClip.GetAnimationClip().length;
        }

        for (int i = 0; i < mixer.GetInputCount(); ++i)
            mixer.SetInputWeight(i, i == m_CurrentClipIndex ? 1.0f : 0.0f);
    }
}

[RequireComponent(typeof(Animator))]
public class CustomPlayableExample : MonoBehaviour
{
    public AnimationClip[] clipsToPlay;
    PlayableGraph graph;

    void Start()
    {
        graph = PlayableGraph.Create("CustomPlayableExample");
        var queuePlayable = ScriptPlayable<PlayQueuePlayable>.Create(graph);
        queuePlayable.GetBehaviour().Initialize(clipsToPlay, queuePlayable, graph);

        var output = AnimationPlayableOutput.Create(graph, "Animation", GetComponent<Animator>());
        output.SetSourcePlayable(queuePlayable, 0);

        graph.Play();
    }

    void OnDisable() => graph.Destroy();
}

Note the pattern: PlayQueuePlayable doesn't play clips directly — it owns and manages a nested AnimationMixerPlayable internally (owner.SetInputCount(1) + graph.Connect(mixer, 0, owner, 0)), so from the outside it behaves like a single node while internally cycling which mixer input has full weight. This "playable that manages a sub-graph" pattern is exactly how more complex custom systems (state-machine-like queues, procedural blend trees) are typically built on top of the raw API.

Mixing & Blending Playables

AnimationMixerPlayable (ScriptReference/Animations.AnimationMixerPlayable.html) is a flat N-input blend node: create it with an input count, connect N source playables to its inputs, and drive each input's contribution with PlayableExtensions.SetInputWeight(index, weight). Unity does not auto-normalize weights for you — Manual/playables-ex-blend-clips.html's pattern of SetInputWeight(0, 1f - weight) / SetInputWeight(1, weight) is a convention the calling code enforces, not a graph guarantee; feed it inputs that don't sum to 1 and you'll get a genuinely over- or under-weighted blend rather than an error. The same mixer works identically whether its inputs are AnimationClipPlayables or an AnimatorControllerPlayable (Manual/playables-ex-blend-clip-controller.html blends a raw clip against a full Animator Controller by wrapping the RuntimeAnimatorController in AnimatorControllerPlayable.Create(graph, controller)) — the mixer only cares that its inputs are playables producing animation data, not what produced that data.

using UnityEngine;
using UnityEngine.Playables;
using UnityEngine.Animations;

[RequireComponent(typeof(Animator))]
public class BlendAnimationClips : MonoBehaviour
{
    public AnimationClip clip0;
    public AnimationClip clip1;
    [Range(0, 1)] public float weight;
    PlayableGraph graph;
    AnimationMixerPlayable mixer;

    void Start()
    {
        graph = PlayableGraph.Create("BlendAnimationClips");
        mixer = AnimationMixerPlayable.Create(graph, 2);

        var output = AnimationPlayableOutput.Create(graph, "Animation", GetComponent<Animator>());
        output.SetSourcePlayable(mixer);

        graph.Connect(AnimationClipPlayable.Create(graph, clip0), 0, mixer, 0);
        graph.Connect(AnimationClipPlayable.Create(graph, clip1), 0, mixer, 1);

        graph.Play();
    }

    void Update()
    {
        weight = Mathf.Clamp01(weight);
        mixer.SetInputWeight(0, 1.0f - weight); // caller is responsible for the weights summing to 1
        mixer.SetInputWeight(1, weight);
    }

    void OnDisable() => graph.Destroy();
}

Source: Manual/playables-ex-blend-clips.html.

For layered rather than flat blending, AnimationLayerMixerPlayable (ScriptReference/Animations.AnimationLayerMixerPlayable.html) is the scripted equivalent of the Animator's built-in layer stack: each input is a layer, SetLayerAdditive(layerIndex, true) makes a layer add on top of layers below it instead of overriding them, and SetLayerMaskFromAvatarMask(layerIndex, avatarMask) restricts a layer to specific bones exactly like an Animator layer's avatar mask. AnimationLayerMixerPlayable.Create(graph, inputCount, singleLayerOptimization) (ScriptReference/Animations.AnimationLayerMixerPlayable.Create.html) takes a singleLayerOptimization flag that pins the first layer's weight to 1 and skips weight math — only safe when you genuinely have one layer; Unity forces it false automatically once you have more than one. You can control the play state of any playable, or a whole branch, via Pause()/Play() (Manual/playables-ex-play-state.html): pausing a node stops its own local time from advancing, but pause/play propagates downward to children regardless of their individual state, so pausing a mixer pauses everything feeding it even if an individual clip playable underneath was independently set to play.

ScriptPlayable for Custom Logic

ScriptPlayable<T> is the generic struct wrapper that turns any PlayableBehaviour-derived type into a first-class graph node (Manual/Playables-ScriptPlayable.html, ScriptReference/Playables.ScriptPlayable_1.html). Because ScriptPlayable<T> is itself an IPlayable, every method on PlayableExtensions (weights, time, speed, duration, connections) works on it identically to a built-in playable type — nothing about it is second-class. This is the mechanism for injecting arbitrary C# logic into the graph's evaluation, as opposed to writing a MonoBehaviour.Update() that pokes at the graph from outside: logic inside PrepareFrame/ProcessFrame runs in lockstep with the graph's own traversal and sees consistent FrameData (deltaTime scaled correctly for the graph's time-update mode and any parent speed multipliers), which polling from Update() does not guarantee.

using UnityEngine;
using UnityEngine.Animations;
using UnityEngine.Playables;

// A ScriptPlayable driving a mixer's weights every frame from inside the graph.
public class BlenderPlayableBehaviour : PlayableBehaviour
{
    public AnimationMixerPlayable mixerPlayable;

    public override void PrepareFrame(Playable playable, FrameData info)
    {
        float blend = Mathf.PingPong((float)playable.GetTime(), 1.0f);
        mixerPlayable.SetInputWeight(0, blend);
        mixerPlayable.SetInputWeight(1, 1.0f - blend);
    }
}

public class PlayableBehaviourSample : MonoBehaviour
{
    PlayableGraph m_Graph;
    public AnimationClip clipA;
    public AnimationClip clipB;

    void Start()
    {
        m_Graph = PlayableGraph.Create();
        var animOutput = AnimationPlayableOutput.Create(m_Graph, "AnimationOutput", GetComponent<Animator>());

        var mixerPlayable = AnimationMixerPlayable.Create(m_Graph, 2);
        var clipPlayableA = AnimationClipPlayable.Create(m_Graph, clipA);
        var clipPlayableB = AnimationClipPlayable.Create(m_Graph, clipB);

        var blenderPlayable = ScriptPlayable<BlenderPlayableBehaviour>.Create(m_Graph, 1);
        blenderPlayable.GetBehaviour().mixerPlayable = mixerPlayable;

        m_Graph.Connect(clipPlayableA, 0, mixerPlayable, 0);
        m_Graph.Connect(clipPlayableB, 0, mixerPlayable, 1);
        m_Graph.Connect(mixerPlayable, 0, blenderPlayable, 0);

        // blenderPlayable is a ScriptPlayable; SetSourcePlayable with an explicit
        // port makes the output pass through to the mixer beneath it.
        animOutput.SetSourcePlayable(blenderPlayable, 0);
        m_Graph.Play();
    }

    void OnDisable() => m_Graph.Destroy();
}

Source: ScriptReference/Playables.PlayableBehaviour.html.

For graphs that need to drive gameplay logic with no animation/audio target at all, pair a ScriptPlayable<T> with a ScriptPlayableOutput (ScriptReference/Playables.ScriptPlayableOutput.html) instead of an AnimationPlayableOutput/AudioPlayableOutput — ProcessFrame becomes the sole place work happens, useful for building custom sequencing/state-machine systems (dialogue queues, scripted event timelines) using the same graph-evaluation guarantees as animation playback.

Integrating with Timeline/Animator

PlayableAsset (ScriptReference/Playables.PlayableAsset.html) is the authoring-time counterpart to a runtime Playable: it's a ScriptableObject whose CreatePlayable(PlayableGraph, GameObject) method injects a subgraph into a caller-owned graph, and its outputs property declares what kind of output(s) that subgraph expects to be connected to. This is exactly the base class Timeline's clip/track assets derive from — when Timeline builds its graph, each track effectively calls CreatePlayable on its asset(s) to populate the graph, then wires up bindings and outputs. You can write your own PlayableAsset subclasses to make custom logic authorable and droppable onto a Timeline track, bridging the low-level API covered here with the editor-facing Timeline workflow (out of scope for this skill — see unity-animation-cinematics for Timeline/Animator/Cinemachine at the workflow level).

PlayableDirector (Manual/class-PlayableDirector.html) is the component that builds and manages a PlayableGraph from a PlayableAsset, exposing Play()/Pause()/Stop()/time/playableAsset plus generic binding storage — it's "primarily used by Timeline" per the manual, but nothing stops you from driving a hand-authored PlayableAsset through a PlayableDirector outside of Timeline. Two methods matter when a director's underlying data changes at runtime: RebuildGraph() (ScriptReference/Playables.PlayableDirector.RebuildGraph.html) discards and reconstructs the whole graph — call it after swapping playableAsset — while RebindPlayableGraphOutputs() (ScriptReference/Playables.PlayableDirector.RebindPlayableGraphOutputs.html) is the cheaper option when only bindings changed (a new Animator/AudioSource/notification receiver appeared) and the graph topology itself is still valid.

AnimationPlayableUtilities (ScriptReference/Playables.AnimationPlayableUtilities.html) exists precisely because building a PlayableGraph by hand for the common cases above is repetitive: PlayClip, PlayMixer, PlayLayerMixer, and PlayAnimatorController each build a minimal graph and hand you back the graph plus the top-level playable in one call — e.g. AnimationPlayableUtilities.PlayClip(animator, clip, out graph) (ScriptReference/Playables.AnimationPlayableUtilities.PlayClip.html) is a one-line equivalent of the "play an animation clip" example above. Reach for these when you just need one of these standard shapes and don't need the full manual control of building each node yourself.

Common Mistakes

Quick Reference

Advanced Notes

• Timeline and Animator are themselves built on PlayableGraph. Manual/class-PlayableDirector.html states the Playable Director component is "primarily used by Unity's Timeline" to store the link between a Timeline instance and asset, hold track/binding data, and control playback — internally, Timeline's TimelineAsset and its tracks are PlayableAsset/PlayableOutput-producing types (Manual/Playables.html, ScriptReference/Playables.PlayableAsset.html) that a PlayableDirector assembles into a graph exactly the way this skill's examples do by hand. The Animator, similarly, exposes its own internal graph via Animator.playableGraph — Animation Rigging's RigBuilder (covered in unity-animation-cinematics) injects its constraint-evaluation playables into that same graph, downstream of the Animator's base pose. Understanding the raw API is therefore not just an alternative to Timeline/Animator — it's literally the substrate both are implemented on,

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