Model Part Keyframe (Data Type)

One point on the timeline of a Model Part Transformation: the value the part should have reached at a given time, or, for a reach, the point its hand or foot should be at.

Fields

Field	Type	Default	Description
`time`	Float	required	When this keyframe is reached, in ticks from the start of the animation. Fractions are allowed.
`value`	Float or Expression	required	The value at this moment, which means the same thing as the transformation's `type` (radians, a scale offset, a pivot offset and so on). An expression is evaluated again as the model renders. It is required, except on a `reach` keyframe that sets `target`.
`target`	Vector	optional	For `reach` only: the point the limb reaches for at this moment, in the same model units as the transformation's `target`. See Drawing a path.
`easing`	Easing	the transformation's `easing`	The curve used to travel into this keyframe from the previous one. The first keyframe's `easing` is never used.

Keyframes are sorted by time when the power loads, so the order you write them in doesn't matter.

How the timeline is read

A reach keyframe can set a value, a target or both. The two are separate tracks: values are read from the keyframes that set a value, and points from the keyframes that set a target, so the reach can fade in on its own schedule while its point moves. With no keyframe values the transformation's value is used, and with no keyframe points its target.
Before the first keyframe's time, the value stays at the first keyframe's value.
After the last keyframe's time, the value stays at the last keyframe's value, unless the transformation sets "loop": true, in which case the timeline wraps back to the start and repeats forever.
With "easing": "step", a keyframe holds the previous value and snaps at the last moment, which is what you want for visible and hidden.
With "easing": "catmullrom", the segment curves smoothly through the neighbouring keyframes instead of running straight between two of them. On a looping timeline the neighbours wrap around, so the loop stays smooth where it joins.

Example

[
  { "time": 0,  "value": 0 },
  { "time": 4,  "value": -1.9, "easing": "ease_out_cubic" },
  { "time": 10, "value": -1.9 },
  { "time": 16, "value": 0,    "easing": "ease_in_out_quad" }
]

This swings to −1.9 radians over 4 ticks with a sharp ease out, holds the pose for 6 ticks, then eases back to rest over 6 more.

On a reach, points and values can share a timeline:

[
  { "time": 0,  "value": 0, "target": [0, -4, -8] },
  { "time": 6,  "value": 1 },
  { "time": 12, "target": [0, -10, -8] },
  { "time": 18, "target": [0, -4, -8] }
]

The hands fade in over 6 ticks while the point they reach for rises from face height to above the head, then comes back down.