Chapter 292: KeyframeTrack

Core Idea

Represents a timed sequence of keyframes, which are composed of lists of times and related values, and which are used to animate a specific property of an object.

Key Concepts

• DefaultInterpolation : InterpolateLinear | InterpolateDiscrete | InterpolateSmooth | InterpolateBezier: The default interpolation type of this keyframe track.
• TimeBufferType : TypedArray | Array: The time buffer type of this keyframe track.
• ValueBufferType : TypedArray | Array: The value buffer type of this keyframe track.
• ValueTypeName : string: The value type name.
• name : string: The track's name can refer to morph targets or bones or possibly other values within an animated object. See PropertyBinding#parseTrackName…
• times : Float32Array: The keyframe times.
• values : Float32Array: The keyframe values.

Reference Tables

Constructor

Signature
`new KeyframeTrack( name : string, times : Array.<number>, values : Array.<(number

Properties

Property	Description
`.DefaultInterpolation : InterpolateLinear	InterpolateDiscrete
`.TimeBufferType : TypedArray	Array`
`.ValueBufferType : TypedArray	Array`
.ValueTypeName : string	The value type name.
.name : string	The track's name can refer to morph targets or bones or possibly other values within an animated object. See PropertyBinding#parseTrackName for the forms of strings that can be parsed for property bi…
.times : Float32Array	The keyframe times.
.values : Float32Array	The keyframe values.

Methods

Method	Description
.InterpolantFactoryMethodBezier( result : TypedArray ) : BezierInterpolant	Factory method for creating a new Bezier interpolant.
.InterpolantFactoryMethodDiscrete( result : TypedArray ) : DiscreteInterpolant	Factory method for creating a new discrete interpolant.
.InterpolantFactoryMethodLinear( result : TypedArray ) : LinearInterpolant	Factory method for creating a new linear interpolant.
.InterpolantFactoryMethodSmooth( result : TypedArray ) : CubicInterpolant	Factory method for creating a new smooth interpolant.
.clone() : KeyframeTrack	Returns a new keyframe track with copied values from this instance.
`.getInterpolation() : InterpolateLinear	InterpolateDiscrete
.getValueSize() : number	Returns the value size.
.optimize() : KeyframeTrack	Optimizes this keyframe track by removing equivalent sequential keys (which are common in morph target sequences).
.scale( timeScale : number ) : KeyframeTrack	Scale all keyframe times by a factor (useful for frame - seconds conversions).
`.setInterpolation( interpolation : InterpolateLinear	InterpolateDiscrete
.shift( timeOffset : number ) : KeyframeTrack	Moves all keyframes either forward or backward in time.
.trim( startTime : number, endTime : number ) : KeyframeTrack	Removes keyframes before and after animation without changing any values within the defined time range.
.validate() : boolean	Performs minimal validation on the keyframe track. Returns true if the values are valid.

Key Takeaways

1. Most relevant properties: DefaultInterpolation, TimeBufferType, ValueBufferType, ValueTypeName.
2. Key methods: InterpolantFactoryMethodBezier, InterpolantFactoryMethodDiscrete, InterpolantFactoryMethodLinear, InterpolantFactoryMethodSmooth.

Connects To

• Source: src/animation/KeyframeTrack.js