KeyframeTrack

A KeyframeTrack is 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.

For an overview of the different elements of the three.js animation system see the “Animation System” article in the “Next Steps” section of the manual.

In contrast to the animation hierarchy of the JSON model format a KeyframeTrack doesn’t store its single keyframes as objects in a “keys” array (holding the times and the values for each frame together in one place).

Instead of this there are always two arrays in a KeyframeTrack: the times array stores the time values for all keyframes of this track in sequential order, and the values array contains the corresponding changing values of the animated property.

A single value, belonging to a certain point of time, can not only be a simple number, but (for example) a vector (if a position is animated) or a quaternion (if a rotation is animated). For this reason the values array (which is a flat array, too) might be three or four times as long as the times array.