Eases on last keyframe: A question. Maybe not an issue.

[ChrisGelles]

In order to better understand the Lottie JSON format, I've been creating simple animations and identifying the properties within the JSON in order to use them interactively later on.

It's a 1 second comp, 24fps.
I made keyframes at frames 0, 12 and 23.

In animating a Shape's Trim Path (end%) and also the Layer's Position, I set up a loop by copy-pasting the keyframes at frame zero into the last frame.

The keyframes from Trim Path (end%) and Position at frame 12 is an arbitrarily different value, just to see some kind of motion.

Anyway, in looking through the JSON, it seems that when adding an Easy Ease, the "Ease" is described by tangent handles, much like a bezier curve, with x and y values for the in- behavior and the out- behavior.

Oddly, the last keyframe has no Ease information, no "i" or "o" properties associated with it.
So far, I cannot tell if this makes a difference in the way the animation behaves.

[bodymovin]

hi, indeed the last keyframe doesn't have the outgoing and ingoing easing values since there is nothing for it to interpolate with

[ChrisGelles]

@bodymovin, though, the in-going ease value interpolates with the previous keyframe... Understandable if there is no outgoing ease value.
However, the incoming interpolation would be affected by position/angle of this tangent handle.

Here's a sketch to explain what I mean:

The red line follows flat tangents (what easy ease produces).
The orange line follows a flat outgoing tangent from the preceding keyframe and also follows an upward-pitched incoming handle on the last keyframe.

Given that the Lottie JSONs do not maintain easing information on the last keyframe of a timeline, the animation curves described in the above sketch could not be replicated by Lottie's playback.

In looping, this could cause slight hitches at the seam of the loop, correct?