Motion on GS_Play Gameplay Framework

GS_MotionTrack

Mon, 01 Jan 0001 00:00:00 +0000

GS_MotionTrack is the abstract base class for all animation tracks in the GS_Motion system. Each track animates one aspect of an entity over a time window within a motion. Domain gems extend this with concrete track types — GS_UI provides 8 LyShine tracks, GS_Juice provides 2 feedback tracks.

For usage guides and setup examples, see The Basics: GS_Core.

Fields

Field	Type	Description
m_id	`AZ::Uuid`	Unique track identifier (auto-generated).
m_identifier	`AZStd::string`	Proxy label — if set, the track appears in the proxy list for entity override targeting.
curveType	`CurveType`	Easing curve applied to track progress (from the Curves utility library).
startTime	`float`	Time offset before the track begins playing (seconds).
duration	`float`	Track playback duration (seconds).
startVarianceMin	`float`	Minimum random variance added to start time.
startVarianceMax	`float`	Maximum random variance added to start time.

Lifecycle

Each track goes through a fixed lifecycle managed by the parent GS_Motion:

GS_Motion

Mon, 01 Jan 0001 00:00:00 +0000

GS_Motion is the playback engine that drives animation tracks. It ticks through all tracks each frame, computes per-track progress windows based on start time and duration, applies easing curves, and calls Update(easedProgress) on each active track. It handles motion lifecycle from initialization through completion.

For usage guides and setup examples, see The Basics: GS_Core.

API Reference

Method	Parameters	Returns	Description
`Play`	—	`void`	Begin playback from the start.
`PlayWithCallback`	`AZStd::function<void()> cb`	`void`	Play and invoke callback on completion.
`Stop`	—	`void`	Stop playback immediately.
`Initialize`	`AZ::EntityId owner`	`void`	Initialize all tracks with the owner entity.
`Unload`	—	`void`	Unload all tracks and clean up.

Fields

Field	Type	Description
motionName	`AZStd::string`	Display name for the motion.
tracks	`vector<GS_MotionTrack*>`	The tracks in this motion.
loop	`bool`	Whether playback loops.
onComplete	`function<void()>`	Completion callback (set via `PlayWithCallback`).

How It Works

Each frame during playback:

GS_MotionComposite

Mon, 01 Jan 0001 00:00:00 +0000

GS_MotionComposite is the runtime instance of a motion, created from a GS_MotionAsset. It deep-copies all tracks so each entity gets independent playback state, and applies proxy overrides to redirect specific tracks to different entities in the hierarchy.

For usage guides and setup examples, see The Basics: GS_Core.

GS_MotionComposite extends GS_Motion. When an asset’s CreateRuntimeComposite() is called, all tracks are SC-cloned (serialization-context cloned) into a new composite instance. This ensures each entity playing the same motion has its own independent track state — no shared mutation.

GS_MotionAsset

Mon, 01 Jan 0001 00:00:00 +0000

GS_MotionAsset is the abstract base class for motion data assets. Domain gems extend this with their own asset type and file extension — GS_UI creates UiAnimationMotionAsset (.uiam), GS_Juice creates FeedbackMotionAsset (.feedbackmotion). Assets are created and edited in the O3DE Asset Editor.

Extends AZ::Data::AssetData. All subclasses require GS_AssetReflectionIncludes.h in their header — see Serialization Helpers.

For usage guides and setup examples, see The Basics: GS_Core.

API Reference

Method	Returns	Description
`GetTrackInfos`	`vector<GS_TrackInfo>`	Returns track UUID + label pairs for proxy list synchronization in the editor.
`CreateRuntimeComposite`	`GS_MotionComposite*`	Factory — deep-copies all asset tracks into a new runtime GS_MotionComposite instance.

GS_TrackInfo

Lightweight struct used for proxy synchronization between asset tracks and instance proxy lists.

GS_Motion

Mon, 01 Jan 0001 00:00:00 +0000

GS_Motion is the framework’s central track-based animation system. It defines abstract base classes that domain gems extend with concrete track types — GS_UI extends it with 8 UI animation tracks (.uiam assets), and GS_Juice extends it with 2 feedback tracks (.feedbackmotion assets). The system handles playback timing, per-track easing, proxy-based entity targeting, and deep-copy runtime instancing from data assets.

For usage guides and setup examples, see The Basics: GS_Core.

Architecture
Core Classes
Domain Extensions
Extension Pattern
See Also

Architecture

GS_MotionTrack (abstract base)
 ├── UiMotionTrack (GS_UI domain base)
 │ ├── UiPositionTrack
 │ ├── UiScaleTrack
 │ ├── UiRotationTrack
 │ ├── UiElementAlphaTrack
 │ ├── UiImageAlphaTrack
 │ ├── UiImageColorTrack
 │ ├── UiTextColorTrack
 │ └── UiTextSizeTrack
 └── FeedbackMotionTrack (GS_Juice domain base)
 ├── FeedbackTransformTrack
 └── FeedbackMaterialTrack

GS_MotionAsset (abstract base)
 ├── UiAnimationMotionAsset (.uiam)
 └── FeedbackMotionAsset (.feedbackmotion)

GS_MotionComposite (runtime instance)
 └── Created by asset's CreateRuntimeComposite()

Core Classes

Class	Description	Page
GS_MotionTrack	Abstract base for all animation tracks — fields, lifecycle, virtual methods, extension guide.	MotionTrack
GS_Motion	Playback engine — ticks tracks, computes per-track progress windows, applies easing, manages lifecycle.	Motion Engine
GS_MotionComposite	Runtime deep-copy instance with proxy entity overrides — created from GS_MotionAsset.	MotionComposite
GS_MotionAsset	Abstract base for motion data assets — holds track definitions and creates runtime composites.	MotionAsset
GS_MotionProxy	Serialized struct for track-to-entity redirection — allows designers to target named tracks at different entities.	MotionProxy

Domain Extensions

GS_Motion is designed to be extended by domain gems. Each domain creates its own track hierarchy, asset type, and file extension.

GS_MotionProxy

Mon, 01 Jan 0001 00:00:00 +0000

GS_MotionProxy is a serialized struct that allows designers to redirect a named track to a different entity in the hierarchy. This enables a single motion asset to animate multiple entities — for example, a UI animation that moves one element while fading another.

For usage guides and setup examples, see The Basics: GS_Core.

Fields

Field	Type	Description
m_trackId	`AZ::Uuid`	References the track’s `m_id`. Matched during `ApplyProxies()`.
m_label	`AZStd::string`	Read-only display label (synced from track info at edit time via `GetTrackInfos()`).
m_proxyEntity	`AZ::EntityId`	The entity this track should target instead of the motion’s owner entity.

How It Works

Edit time: The proxy list syncs from the asset’s track info. Each track with an m_identifier (non-empty label) appears as a proxy slot in the inspector.
Designer assignment: The designer drags an entity reference into the proxy’s m_proxyEntity field.
Runtime: When GS_MotionComposite::ApplyProxies() runs, it matches each proxy’s m_trackId to a track’s m_id and overrides that track’s target entity.
Playback: The track now animates the proxy entity instead of the motion’s owner.

Usage

Proxies are embedded in instance wrapper structs (e.g., UiAnimationMotion, FeedbackMotion) alongside the asset reference. Components serialize the proxy list, and the wrapper handles synchronization with the asset.

Motion System

Mon, 01 Jan 0001 00:00:00 +0000

GS_Motion is a track-based animation engine built into GS_Core. It drives timed property changes — position, rotation, scale, color, opacity — through authored data assets rather than hand-coded interpolation scripts. Domain gems extend GS_Motion with their own track types: GS_UI adds 8 LyShine-specific tracks for UI animation, and GS_Juice adds transform and material tracks for game feel feedback.

For architecture details, the domain extension pattern, and all track types, see the Framework API reference.

Motion on GS_Play Gameplay Framework

GS_MotionTrack

Fields

Lifecycle

GS_Motion

API Reference

Fields

How It Works

GS_MotionComposite

GS_MotionAsset

API Reference

GS_TrackInfo

GS_Motion

Contents

Architecture

Core Classes

Domain Extensions

GS_MotionProxy

Fields

How It Works

Usage

Motion System