> For the complete documentation index, see [llms.txt](https://multiset.gitbook.io/multiset/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://multiset.gitbook.io/multiset/web-sdk/webxr-sdk/api-reference/needleadapter.md). # NeedleAdapter ```typescript import { NeedleAdapter } from '@multisetai/vps/needle'; ``` A Needle Engine `Behaviour` that owns `XRSessionManager` and wires it to Needle's render loop. It replaces Needle's built-in WebXR session on `awake()`. Use `NeedleAdapter` programmatically for custom logic; use `MultisetVPS` when you want Inspector-driven setup. ### Constructor ```typescript new NeedleAdapter(options: INeedleAdapterOptions) ``` ### Options | Parameter | Type | Default | Description | | ----------------------- | ----------------------------------------------------------------------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------- | | `client` | `MultisetClient` | Required | Authorized HTTP client | | `sessionOptions` | `Omit` | — | All `XRSessionManager` options except `client`. See [XRSessionManager](/multiset/web-sdk/webxr-sdk/api-reference/xrsessionmanager.md). | | `showMesh` | `boolean` | `false` | Download and display the map mesh after localization | | `showGizmo` | `boolean` | `false` | Display a transform gizmo at the map origin | | `showObjectMeshes` | `boolean` | `false` | Download and display 3D outline meshes for detected objects | | `useDefaultButton` | `boolean` | `true` | Mount the built-in AR button in `awake()` | | `buttonContainer` | `HTMLElement` | — | Container element for the AR button | | `onButtonCreated` | `(button: HTMLButtonElement) => void` | — | Called when the button is created | | `onXRFrame` | `(event: IXRFrameEvent) => void` | — | Called every XR frame | | `onLocalizationSuccess` | `(result: ILocalizeAndMapDetails, worldFromMap: THREE.Matrix4) => void` | — | Called after successful localization | | `onObjectMeshLoaded` | `(objectCode: string) => void` | — | Called when an object mesh finishes loading | ### Static Methods | Method | Returns | Description | | ----------------------------- | ------------------ | ------------------------------------------ | | `NeedleAdapter.isSupported()` | `Promise` | Check if the browser supports immersive-ar | ### Instance Methods | Method | Returns | Description | | ------------------------------------ | ------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------- | | `startSession()` | `Promise` | Start the AR session from a user gesture handler | | `stopSession()` | `void` | Stop the active session | | `localizeFrame()` | `Promise` | Capture and localize one frame | | `trackObjects()` | `Promise` | Capture and run object detection | | `isActive()` | `boolean` | Whether an AR session is running | | `clearObjectMeshes()` | `void` | Remove all loaded object meshes | | `getSession()` | `XRSessionManager` | Access the underlying session manager. Use `getSession().getOverlayRoot()` to mount UI that receives taps during a session. | | `registerAnchor(anchor: IMapAnchor)` | `void` | Wire a runtime-spawned `MapAnchor` to this adapter. Replays the last localization result immediately if one is available. | ### Properties | Property | Type | Description | | -------------- | --------- | ----------------------------------------------- | | `isLocalizing` | `boolean` | Whether localization or tracking is in progress | ### Events and Scene Access The `onLocalizationSuccess` and `onXRFrame` options are single-slot: setting one replaces it. Use the listeners below when more than one part of your app needs to react. Anything layered on the adapter, including [MapSpace](/multiset/web-sdk/webxr-sdk/api-reference/mapspace.md) and [Navigation](/multiset/web-sdk/webxr-sdk/features/navigation.md), uses them, so they compose. Every `add*Listener` **returns its own unsubscribe function**, which is usually easier than keeping a reference for the matching `remove*Listener`. | Method | Returns | Description | | -------------------------------- | --------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | | `addLocalizationListener(fn)` | `() => void` | `fn(result, worldFromMap)` after every successful localization | | `removeLocalizationListener(fn)` | `void` | Unsubscribe. Equivalent to calling the returned function. | | `addSessionStartListener(fn)` | `() => void` | Fires when the AR session starts | | `removeSessionStartListener(fn)` | `void` | Unsubscribe | | `addSessionEndListener(fn)` | `() => void` | Fires when the AR session ends | | `removeSessionEndListener(fn)` | `void` | Unsubscribe | | `addFrameListener(fn)` | `() => void` | `fn(event)` every XR frame, after camera matrices are synced and before the scene renders, so anything you move lands in the same frame | | `removeFrameListener(fn)` | `void` | Unsubscribe | | `waitForLocalization()` | `Promise` | Resolves immediately if the current session has already localized, otherwise on the next success. Never rejects. | | `getLastLocalization()` | `ILocalizationSnapshot \| null` | The current session's most recent result and its `worldFromMap`. Cleared when the session ends, so a stale pose can never be replayed into a new session. | | `getScene()` | `THREE.Scene` | The active scene | | `getCamera()` | `THREE.Camera` | The XR-driven camera | `waitForLocalization()` replaces the usual "do this once we are localized" callback plumbing: ```typescript await adapter.waitForLocalization(); // the map frame is positioned; safe to read poses or start navigation ``` {% hint style="warning" %} Read the camera pose with `camera.getWorldPosition(target)` or `camera.matrixWorld`, never `camera.position`. During a session the adapter writes `matrixWorld` directly and leaves `position` and `quaternion` untouched, so reading `position` returns a stale value. {% endhint %} ### IVpsAdapter Both adapters satisfy the same `IVpsAdapter` contract, so a feature written against it works on either one and on any future adapter. ```typescript import type { IVpsAdapter } from '@multisetai/vps/three'; function attachMyFeature(adapter: IVpsAdapter) { return adapter.addLocalizationListener((result, worldFromMap) => { // ... }); } ``` They satisfy it **structurally**, so neither declares `implements`. A compile-time guard in each entry point fails the build if one drifts from the interface. `ILocalizationSnapshot` is `{ result: ILocalizeAndMapDetails; worldFromMap: THREE.Matrix4 }`. ### Needle Lifecycle | Method | Called when | | ------------- | ------------------------------------------------------------------------------------------------------------- | | `awake()` | Component added to scene. Disables Needle's built-in WebXR, creates `XRSessionManager`, mounts the AR button. | | `onDestroy()` | Component removed. Disposes session, world, removes all listeners. | --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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