GS_MotionTrack

Abstract base class for all animation tracks — fields, lifecycle, and virtual methods for domain extension.

Tags:

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:

Phase	Method	Description
Initialize	`Init(AZ::EntityId owner)`	Stores the owner entity. Called once when the motion is initialized.
Start	`Start()`	Called when the track’s time window begins.
Update	`Update(float easedProgress)`	Called each frame with eased progress (0 → 1). Override this in concrete tracks.
End	`End()`	Called when the track’s time window completes.
Unload	`Unload()`	Cleanup. Called when the motion is unloaded.

Virtual Methods

These methods must be overridden in concrete track implementations:

Method	Returns	Description
`Update(float easedProgress)`	`void`	Apply the animation at the given eased progress value (0 → 1).
`GetTypeName()`	`AZStd::string`	Return the track’s display name for proxy labels in the editor.

Extension Guide

To create a new domain of animation tracks:

Create a domain base track: class MyTrack : public GS_Core::GS_MotionTrack — this serves as the common base for all tracks in your domain.
Create concrete tracks extending the domain base — each overrides Update(float easedProgress) to animate a specific property.
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.

Get GS_Core

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