Function easing

easing(
    type: number,
    x: number,
    easingLeft?: number,
    easingRight?: number,
    bezierPoints?: number[],
): number
Evaluate an RPE easing at progress x.

Handles sub-range clamping (easingLeft/easingRight) and optional cubic-bezier override. This is the main function you call to get an eased progress value from an RPE event.
Parameters
- type: number
  RPE easing type (1–28). Invalid types default to linear (1).
- x: number
  Raw progress ∈ [0, 1].
- easingLeft: number = 0
  Left sub-range boundary (default 0). Use with easingRight to restrict the easing to a portion of the curve.
- easingRight: number = 1
  Right sub-range boundary (default 1).
- OptionalbezierPoints: number[]
  If provided (4 numbers [x1, y1, x2, y2]), uses a CSS-style cubic bezier instead of the type curve.
Returns number
The eased progress value, usually ∈ [0, 1].
Example
```
easing(8, 0.5);              // CubicOut at 50% → ~0.875
easing(1, 0.5, 0.25, 0.75); // Linear, sub-range [0.25, 0.75]
easing(1, 0.5, 0, 1, [0.4, 0, 0.2, 1]); // Custom bezier
```
- Defined in easing.ts:186