# `Camera.set`

> Contract 2.0.0 · package sha256 `a857eca95b35921109faf997094bb4192f12527d9d0fcd4be7e97f06425bad6e` · generated from `configurator-runtime.d.ts` by `services/onsite-scripter/scripts/build-contract-docs.mjs`; edit the source, not this file.

Method of [`Camera`](Camera.md) · stable · since 2.0.0 · called as `session.camera.set`

```ts
set(view: CameraView | LookAtView, options?: CameraCommitOptions<C> & CameraMoveOptions): Promise<Report>;
```

Moves the camera to a view (look-only, replacing; target: the view). `durationMs: 0` lands
exactly, with no damping. A [`LookAtView`](LookAtView.md) also clears the focal offset. Outcome: 'committed'
when the move ends, or when a newer view write or a shopper's pointer or touch gesture
('camera:control-start'; not a wheel, which only changes the distance the move lands at)
takes it over, so 'committed' does not say the view landed; through
a `tx`, 'deferred'. To act only on a landed move (writing [`limits`](Camera.limits.md), which clamp the current
view), note a gesture, and any newer view write of your own, while the move runs (second
example); [`limits`](Camera.limits.md) is a separate target, so it can also be written in the move's task.
Not for: a camera that moves every frame, which is [`Frame.camera(view)`](Frame.camera.md) in an [`onFrame`](Session.onFrame.md) hook.
Errors: rejects HoloInputError on an invalid view; AbortError when `signal` aborts before the
move ends, and the camera stops where the last frame drew it ([`CameraMoveOptions`](CameraMoveOptions.md)). To stop a
move in place without a rejection, `set` the drawn view (`azimuthDeg`, `polarDeg`, `distance`,
`target`, `focalOffset` of [`state`](Camera.state.md)) with `durationMs: 0`: it takes the move over.

## Options

Through [`Session`](Session.md):

| Option | Type | Default | What it does |
| --- | --- | --- | --- |
| `actor` | `Actor` | the `expectGroup`'s actor when one is given, else 'app' | Who made the write. |
| `durationMs` | `number` | 0 | 0 lands exactly, without damping, before the next frame. |
| `easing` | `Easing \| 'damped'` | 'easeInOut' | The move's time curve: an [`Easing`](Easing.md), or `'damped'`, a critically damped spring with no overshoot, which is 1.x's `transition: true` glide. |
| `expectRevision` | `number` | undefined (no check) | If-match on [`session.revision`](Session.revision.md). |
| `origin` | `string` | null | Your tag, echoed unchanged in [`Report.origin`](ReportFields.origin.md) and `cause.origin`. |
| `signal` | `AbortSignal` | undefined | Cancels this call; the member's JSDoc says what an abort does. |

Refused here (typed `never`, so passing one fails to compile): `dryRun`, `expectGroup`, `supersede`, `undo`.

Through [`Tx`](Tx.md):

| Option | Type | Default | What it does |
| --- | --- | --- | --- |
| `durationMs` | `number` | 0 | 0 lands exactly, without damping, before the next frame. |
| `easing` | `Easing \| 'damped'` | 'easeInOut' | The move's time curve: an [`Easing`](Easing.md), or `'damped'`, a critically damped spring with no overshoot, which is 1.x's `transition: true` glide. |
| `signal` | `AbortSignal` | undefined | Cancels this call; the member's JSDoc says what an abort does. |

Refused here (typed `never`, so passing one fails to compile): `actor`, `checkpoint`, `dryRun`, `expectGroup`, `expectRevision`, `origin`, `supersede`, `undo`.

## Abort (`signal`)

This call is a write (`SignalOption.signal`, [the kinds of call](../read-this-first.md#conventions)).

> A write: before the commit point it rolls back and rejects AbortError; after it, no effect, except that a running camera move stops where the last frame drew it (`CameraMoveOptions`).
>
> Through a `tx` the commit point is the transaction's: aborting a write still loading rejects AbortError and stages nothing (catch it: unobserved, it rolls the transaction back, spec section 6.1, O6); aborting one already staged unstages it, its paths keeping the latest other write to them as after a failed savepoint (O7), and its Promise stays resolved 'staged'.

## Examples

Imports: values (`has`, `validate`, the `Holo*Error` classes, the pure helpers) from `@holostep-configurators/runtime-client`, types from `@holostep-configurators/runtime-client/contract`, `/math` and `/testing` names from those entries; `boot` from the runtime module the root's `loadRuntimeAtFloor` resolves to. A type your page defines is your app's: declare it there, never import it from the package.

Compiled under the contract's strict settings (`examples/declaration/10-Camera.set-1.ts`):

```ts
import type { Session } from '@holostep-configurators/runtime-client/contract';
declare const session: Session;
declare const signal: AbortSignal;
declare const sheetHeightPx: number;
// separate targets: neither waits for the other
await Promise.all([
  session.camera.lens(
    { insets: { top: 0, right: 0, bottom: sheetHeightPx, left: 0 } },
    { durationMs: 300 },
  ),
  session.camera.set(
    { position: { x: 2, y: 1.6, z: 3 }, target: { x: 0, y: 0.8, z: 0 } },
    { durationMs: 600 },
  ),
]);
```

Compiled under the contract's strict settings (`examples/declaration/10-Camera.set-2.ts`):

```ts
import type { Session } from '@holostep-configurators/runtime-client/contract';
declare const session: Session;
declare const signal: AbortSignal;
// narrow the limits only once the opening shot has landed
let takenOver = false;
const stop = session.on('camera:control-start', () => { takenOver = true; }, { signal });
await session.camera.set(
  { position: { x: 2, y: 1.6, z: 3 }, target: { x: 0, y: 0.8, z: 0 } },
  { durationMs: 800 },
);
stop();
if (!takenOver) await session.camera.limits({ minAzimuthDeg: -10, maxAzimuthDeg: 70 });
```

## Generic-API test (spec 3.1)

| Rule | Result |
| --- | --- |
| 1. Neutral name | pass: `set` names no product |
| 2. A precedent | pass: [Unity Transform.LookAt](https://docs.unity3d.com/ScriptReference/Transform.LookAt.html) (row `G42`); [Babylon.js ArcRotateCamera setTarget, setPosition](https://github.com/BabylonJS/Babylon.js/blob/master/packages/dev/core/src/Cameras/arcRotateCamera.ts) (row `G42`) |
| 3. Two apps, or labs | pass: 28 apps (ledger: app-fc306ec3dc; fleet cross-check: app-04c2774145, app-0c773a4ee3, app-37356bf09f, app-378d190f1b, app-4762caacdc, app-4f16d2f6da, app-4fd23bc869, app-510d750508 and 20 more) |
| 4. The cheaper fix first | decided per need in Appendix B: rows `G42` at tier stable (a member only where no rule, data, asset or app code serves the need) |