GS_Motion

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()

1 - GS_MotionTrack

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

Lifecycle

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

Virtual Methods

These methods must be overridden in concrete track implementations:

Extension Guide

To create a new domain of animation tracks:

1. Create a domain base track: class MyTrack : public GS_Core::GS_MotionTrack — this serves as the common base for all tracks in your domain.
2. Create concrete tracks extending the domain base — each overrides Update(float easedProgress) to animate a specific property.
3. Reflect the track class using O3DE’s SerializeContext and EditContext. The system discovers the new type automatically.

Critical: Track vectors must use raw pointers (vector<MyTrack*>). Never use unique_ptr — O3DE SerializeContext requires raw pointers for polymorphic enumeration in the asset editor.

See Also

• GS_Motion (Engine)
• GS_MotionAsset
• GS_MotionProxy
• GS_Motion Overview

Get GS_Core

GS_Core — Explore this gem on the product page and add it to your project.

2 - GS_Motion

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

Fields

How It Works

Each frame during playback:

1. The motion calculates the global elapsed time.
2. For each track, it computes the track-local progress based on startTime and duration.
3. If the track is within its active window, the progress is eased using the track’s curveType.
4. Update(easedProgress) is called on the track with the eased value (0 → 1).
5. When all tracks complete, OnMotionComplete() is called.

Virtual Methods

See Also

• GS_MotionTrack
• GS_MotionComposite
• GS_MotionAsset
• GS_Motion Overview

Get GS_Core

GS_Core — Explore this gem on the product page and add it to your project.

3 - GS_MotionComposite

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.

API Reference

How It Works

1. Creation: GS_MotionAsset::CreateRuntimeComposite() deep-copies all asset tracks into a new composite.
2. Proxy Application: ApplyProxies() walks the proxy list, matching each proxy’s m_trackId to a track’s m_id. Matched tracks redirect their owner entity to the proxy’s m_proxyEntity.
3. Playback: The composite plays exactly like a regular GS_Motion — it ticks tracks, applies easing, and calls Update().
4. Cleanup: On Unload(), the composite cleans up all deep-copied tracks.

See Also

• GS_MotionTrack
• GS_Motion (Engine)
• GS_MotionAsset
• GS_MotionProxy
• GS_Motion Overview

Get GS_Core

GS_Core — Explore this gem on the product page and add it to your project.

4 - GS_MotionAsset

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

GS_TrackInfo

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

Domain Extensions

Extension Guide

To create a new domain asset type:

1. Create class MyAsset : public GS_Core::GS_MotionAsset with vector<MyDomainTrack*> m_tracks. Include GS_AssetReflectionIncludes.h in your asset’s header — see Serialization Helpers.
2. Implement GetTrackInfos() — iterate tracks and return UUID + label pairs.
3. Implement CreateRuntimeComposite() — deep-copy tracks into a new GS_MotionComposite.
4. Register the asset type in your gem’s DataAssetsSystemComponent.
5. Add a .setreg entry for the asset processor to recognize your file extension.

Critical: Track vectors must use raw pointers (vector<MyTrack*>). O3DE SerializeContext requires raw pointers for polymorphic enumeration.

See Also

• GS_MotionTrack
• GS_MotionComposite
• GS_MotionProxy
• GS_Motion Overview

Get GS_Core

GS_Core — Explore this gem on the product page and add it to your project.

5 - GS_MotionProxy

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

How It Works

1. 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.
2. Designer assignment: The designer drags an entity reference into the proxy’s m_proxyEntity field.
3. 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.
4. 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.

Only tracks with a non-empty m_identifier appear in the proxy list. Tracks without an identifier always animate the owner entity.

See Also

• GS_MotionTrack
• GS_MotionComposite
• GS_MotionAsset
• GS_Motion Overview

Get GS_Core

GS_Core — Explore this gem on the product page and add it to your project.