# States: everything one pose can drive

A **State** is far more than a transform. It is one `FMovaIxActionState`, carrying a
core Transform bundle plus optional groups that fire when a keyframe referencing it
is reached.

<!-- shot:control-panel-picker -->
```{image} ../_static/screenshots/shot-control-panel-picker-mockup.svg
:alt: control panel picker (placeholder mockup)
:width: 100%
```

Save the real screenshot as: `shot-control-panel-picker.png`

```{image} ../_static/screenshots/shot-control-panel-picker.png
:alt: control panel picker (real screenshot)
:width: 100%
```
<!-- /shot -->

## Transform (always present)

Relative `Location`, `Rotation`, `Scale`, and `bVisible`. Deltas compose relative to
the target's start, its `@Zero` pose, or an `OffsetTarget`, per the owning Group's
`OffsetMode`.

## Audio

- **Trigger**: a one-shot sound (fade, offset, pitch, volume, trim) fired the
  instant the keyframe is reached.
- **Continuous**: a looping sound that plays for as long as the state is active,
  with its own fade/pitch/volume and optional `Attenuation`.

## Niagara

A `System` spawned at the keyframe, attached to a resolved `Target` component with
an `Offset`. `OneShot` fires a burst and detaches; `WhileActive` keeps the effect
running until the state is left (a torch flame, a force field hum).

## Physics

- **Impulse**: a one-shot push, applied at the keyframe.
- **ContinuousForce**: a per-frame force, with local application points, active
  while the state holds (a fan's wind zone, a conveyor's drag).
- **Vibration**: procedural amplitude/frequency/impulse shaking for rumbling
  machinery, no baked animation required.
- **Travel-speed clamps**: cap a state's segment by cm/s or deg/s and the timing
  **auto-times** by distance: the same "go to floor 3" state takes proportionally
  longer than "go to floor 1" without a separate setup step.

## Visuals

`LightColor` / `LightIntensity` / `LightTemperature` when the target is a light
component, and per-slot **Material** overrides for any primitive.

## Animation

An `AnimSequence` or `AnimMontage` played on a rigged (skeletal) target, with
`BlendIn`, `bLooping`, `PlayRate`: usable alongside or instead of the procedural
keyframes, so a hand-animated character interaction and a procedurally-moved prop
share the same setup surface.

## Params

A gameplay payload for your own branching logic: an `Action` name to run elsewhere,
a `Number`, a `Tag`, and free `Text`. Read these from Blueprint on the state-reached
event to drive quest flags, counters, or dialogue triggers without adding a new
system.

## Special states are not written states

`@Zero`, `@Current`, `@Start`, `@Loop`, `@Stop`, `@StopNow` are runtime markers
resolved by logic (see {doc}`model`), not entries you create in `ActionStates`,
they are always available and the validation chips never mark them unresolved.

## When a state is actually recorded

A target's state is written **when the animation reaches that keyframe**, not when it
starts moving. A drawer halfway open is recorded as neither open nor closed.

To keep gates usable mid-move, the runtime also records where a target is *heading*
the moment playback starts, and clears it on arrival. A tag picks which of the two
it means:

| Written | Reads as |
|---|---|
| `:Open` | heading there **or** already there: the default |
| `:=Open` | fully arrived |
| `:~Open` | still traveling |

It stops two colliding drawers from both opening: the second asks
`?@Other:!Open`, false while the first is still sliding. See {doc}`tag-grammar`.