> ## Documentation Index
> Fetch the complete documentation index at: https://rive.app/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Interpolator

An interpolator: eases keyframes, state transitions, layout animations and
interpolating data converters.

Rive creates an instance per owner instance: each playing animation gets one
per keyframe, each state machine one per interpolator its transitions use,
each artboard one per interpolator its layout styles use, and each bound
converter its own. Transitions or layout styles that use the same
interpolator share its instance, as do layouts that inherit their animation
from a parent layout (including nested artboards and list items).

So `transform` and `transformValue` can be called many times per frame, by
several layouts, in any order. Compute the result from `value` (and `from`
and `to`), the inputs and whatever `init` set up; don't keep progress in
`self` between calls.

## Methods

### `init`

<div class="signature">
  ```lua theme={null}
  init(self: T, context: Context) -> boolean
  ```
</div>

### `transform`

<div class="signature">
  ```lua theme={null}
  transform(self: T, value: number) -> number
  ```
</div>

Maps a linear progress `value` in 0..1 to an eased one.

### `transformValue`

<div class="signature">
  ```lua theme={null}
  transformValue(self: T, from: number, to: number, value: number) -> number
  ```
</div>

Returns the value between `from` and `to` at linear progress `value`.