Animation Tracks & Keyframes

Texturge provides 10 typed animation tracks, each controlling one property component of FAnimationFrameData. Multiple tracks combine and layer to form complete per-character animation effects.

Track Model

FTextAnimationTrack Structure

struct FTextAnimationTrack
{
    FGuid TrackId;          // Unique track identifier
    FName TrackName;        // Track name (for Blueprint identification)
    ETextAnimationTrackType TrackType;  // Track type (determines which property to control)
    float StartTime;        // Start time (seconds)
    float Duration;         // Duration (seconds)
    float TrackWeight;      // Track weight (0~1)
    bool bEnabled;          // Whether enabled
    bool bInvertOpacity;    // Invert opacity (opacity tracks only)
    ETextAnimationBlendMode BlendMode;  // Blend mode
    TArray<FKeyFrame> KeyFrames;        // Keyframe array
    // -- Character application & timing --
    ECharacterApplicationMode ApplicationMode;  // Application mode
    int32 ApplicationInterval;      // Interval count
    bool bApplyToFirstChar;         // Whether to apply to first character
    float RandomProbability;        // Random proportion
    ETextAnimationTimingMode TimingMode;  // Timing mode
    float TotalTextDuration;        // Total text duration
    int32 CharacterDelayFrames;     // Inter-character delay frames
};

Track Type Overview

Float Properties

Track	Enum Value	FAnimationFrameData Field	Description
Opacity	Opacity	Opacity (0~1)	Character transparency/reveal effect. Use with bInvertOpacity for default-hidden→reveal.
Letter Spacing	LetterSpacing	LetterSpacing (px)	Per-character letter spacing animation
Rotation	Rotation	Rotation (degrees)	Character rotation, centered on Pivot

Vector2D Properties

Track	Enum Value	Field	Description
Translation	Translation	PositionOffset (px)	Character position offset. X/Y independently controlled
Scale	Scale	Scale (X/Y)	Character scale. (1,1) = original size
Shear	Shear	Shear (X/Y)	Shear transform. (0,0) = no shear
Pivot	Pivot	Pivot (0~1)	Transform pivot. (0.5,0.5) = character center
Shadow Offset	ShadowOffset	ShadowOffset (px)	Character shadow position offset

Color Properties

Track	Enum Value	Field	Description
Color	Color	Color	Character tint color. Can blend with original text color
Shadow Color	ShadowColor	ShadowColor	Character shadow color. Transparent = no shadow

Frame Data Structure

The complete state of each character in each frame is described by the FAnimationFrameData struct:

struct FAnimationFrameData
{
    // Transform
    FVector2D PositionOffset;  // Position offset
    FVector2D Scale;           // Scale (1,1)
    float Rotation;            // Rotation angle
    FVector2D Shear;           // Shear transform
    FVector2D Pivot;           // Transform pivot (0.5,0.5)
    // Color
    FLinearColor Color;        // Tint (White = no tint)
    float Opacity;             // Opacity (1 = fully visible)
    // Shadow
    FVector2D ShadowOffset;    // Shadow offset
    FLinearColor ShadowColor;  // Shadow color
    // Typography
    float LetterSpacing;       // Letter spacing (0 = default)
};

Identity Frame is the frame data with all default values — Opacity=1, Scale=(1,1), Color=White, Pivot=(0.5,0.5), remaining fields at 0. Unrevealed characters return an identity frame with Opacity=0, producing no visible rendering.

Keyframe System

FKeyFrame Structure

struct FKeyFrame
{
    FGuid KeyId;                // Unique keyframe identifier
    float Time;                 // Time (relative to track start, seconds)
    float FloatValue;           // Float type value
    FVector2D Vector2DValue;    // Vector2D type value
    FLinearColor ColorValue;    // Color type value
    EKeyInterp InterpType;      // Interpolation type
};

Each keyframe uses only the field corresponding to its track’s value type — Float tracks use FloatValue, Vector2D tracks use Vector2DValue, Color tracks use ColorValue.

Interpolation Types

Interpolation	Enum Value	Curve Shape
Linear	Linear	Uniform straight-line transition
Cubic	Cubic	Bezier smooth curve
Constant	Constant	No transition, held until next keyframe
Cubic In-Out	CubicInOut	S-curve easing

Interpolation is implemented in UTextAnimInstance’s static methods:

• InterpolateKeyFramesFloat() — float interpolation
• InterpolateKeyFramesVector2D() — vector interpolation
• InterpolateKeyFramesColor() — color interpolation

Track Blend Modes

When multiple tracks are layered, blend modes control how they interact:

Blend Mode	Enum Value	Behavior
Additive	Additive	Add track result item-by-item to the base value
Override	Override	Track result fully replaces the base value
Multiply	Multiply	Multiply track result with the base value item-by-item
CrossFade	CrossFade	Cross-fade between track result and base value by weight

Blending is performed in UTextAnimInstance::BlendFrames(), weighted by track weight (TrackWeight).

Character Application Modes

Determines which characters the animation applies to:

Mode	Enum Value	Description
Per-Character	PerCharacter	All characters receive the animation (default)
Interval	Interval	Animation applied every N characters. Controlled by ApplicationInterval and bApplyToFirstChar
Random	Random	Randomly select characters by RandomProbability proportion

Timing Modes

Determines how per-character animation duration is calculated. ETextAnimationTimingMode in FTextAnimationTrack maps to EDurationMode in the Sequencer root track:

Sequencer Root Label	Track Struct Label	Enum Value	Description
Per-Character	Character Animation Duration	PerCharacterDuration	Each character animates independently; total = characters × Duration
Fixed Total	Total Text Animation Duration	TotalDuration	All characters complete within the specified total duration, evenly distributed

CharacterDelayFrames controls the start delay between characters (in frames). 0 means all characters begin animating simultaneously.