Class XrAnchors

Anchors provide an ability to specify a point in the world that needs to be updated to correctly reflect the evolving understanding of the world by the underlying AR system, such that the anchor remains aligned with the same place in the physical world. Anchors tend to persist better relative to the real world, especially during a longer session with lots of movement.

app.xr.start(camera, pc.XRTYPE_AR, pc.XRSPACE_LOCALFLOOR, {
    anchors: true
});

Hierarchy (view full)

Accessors

available list persistence supported uuids

Methods

create fire forget hasEvent off on once restore

Events

EVENT_ADD EVENT_AVAILABLE EVENT_DESTROY EVENT_ERROR EVENT_UNAVAILABLE

Accessors

available

list

persistence

supported

uuids

Methods

create

  • create(position, rotation?, callback?): void

  • Create an anchor using position and rotation, or from hit test result.

    Parameters

    • position: Vec3 | XRHitTestResult

      Position for an anchor or a hit test result.

    • Optionalrotation: Quat | XrAnchorCreateCallback

      Rotation for an anchor or a callback if creating from a hit test result.

    • Optionalcallback: XrAnchorCreateCallback

      Callback to fire when anchor was created or failed to be created.

    Returns void

    Example

    // create an anchor using a position and rotation
    app.xr.anchors.create(position, rotation, function (err, anchor) {
        if (!err) {
            // new anchor has been created
        }
    });

    Example

    // create an anchor from a hit test result
    hitTestSource.on('result', (position, rotation, inputSource, hitTestResult) => {
        app.xr.anchors.create(hitTestResult, function (err, anchor) {
            if (!err) {
                // new anchor has been created
            }
        });
    });

fire

  • fire(name, arg1?, arg2?, arg3?, arg4?, arg5?, arg6?, arg7?, arg8?): EventHandler

  • Fire an event, all additional arguments are passed on to the event listener.

    Parameters

    • name: string

      Name of event to fire.

    • Optionalarg1: any

      First argument that is passed to the event handler.

    • Optionalarg2: any

      Second argument that is passed to the event handler.

    • Optionalarg3: any

      Third argument that is passed to the event handler.

    • Optionalarg4: any

      Fourth argument that is passed to the event handler.

    • Optionalarg5: any

      Fifth argument that is passed to the event handler.

    • Optionalarg6: any

      Sixth argument that is passed to the event handler.

    • Optionalarg7: any

      Seventh argument that is passed to the event handler.

    • Optionalarg8: any

      Eighth argument that is passed to the event handler.

    Returns EventHandler

    Self for chaining.

    Example

    obj.fire('test', 'This is the message');

forget

  • forget(uuid, callback?): void

  • Forget an anchor by removing its UUID from underlying systems.

    Parameters

    • uuid: string

      UUID string associated with persistent anchor.

    • Optionalcallback: XrAnchorForgetCallback

      Callback to fire when anchor persistent data was removed or error if failed.

    Returns void

    Example

    // forget all available anchors
    const uuids = app.xr.anchors.uuids;
    for(let i = 0; i < uuids.length; i++) {
        app.xr.anchors.forget(uuids[i]);
    }

hasEvent

  • hasEvent(name): boolean

  • Test if there are any handlers bound to an event name.

    Parameters

    • name: string

      The name of the event to test.

    Returns boolean

    True if the object has handlers bound to the specified event name.

    Example

    obj.on('test', function () { }); // bind an event to 'test'
    obj.hasEvent('test'); // returns true
    obj.hasEvent('hello'); // returns false

off

  • off(name?, callback?, scope?): EventHandler

  • Detach an event handler from an event. If callback is not provided then all callbacks are unbound from the event, if scope is not provided then all events with the callback will be unbound.

    Parameters

    • Optionalname: string

      Name of the event to unbind.

    • Optionalcallback: HandleEventCallback

      Function to be unbound.

    • Optionalscope: object

      Scope that was used as the this when the event is fired.

    Returns EventHandler

    Self for chaining.

    Example

    const handler = function () {
    };
    obj.on('test', handler);

    obj.off(); // Removes all events
    obj.off('test'); // Removes all events called 'test'
    obj.off('test', handler); // Removes all handler functions, called 'test'
    obj.off('test', handler, this); // Removes all handler functions, called 'test' with scope this

on

  • on(name, callback, scope?): EventHandle

  • Attach an event handler to an event.

    Parameters

    • name: string

      Name of the event to bind the callback to.

    • callback: HandleEventCallback

      Function that is called when event is fired. Note the callback is limited to 8 arguments.

    • Optionalscope: object = ...

      Object to use as 'this' when the event is fired, defaults to current this.

    Returns EventHandle

    Can be used for removing event in the future.

    Example

    obj.on('test', function (a, b) {
        console.log(a + b);
    });
    obj.fire('test', 1, 2); // prints 3 to the console

    Example

    const evt = obj.on('test', function (a, b) {
        console.log(a + b);
    });
    // some time later
    evt.off();

once

  • once(name, callback, scope?): EventHandle

  • Attach an event handler to an event. This handler will be removed after being fired once.

    Parameters

    • name: string

      Name of the event to bind the callback to.

    • callback: HandleEventCallback

      Function that is called when event is fired. Note the callback is limited to 8 arguments.

    • Optionalscope: object = ...

      Object to use as 'this' when the event is fired, defaults to current this.

    Returns EventHandle

    • can be used for removing event in the future.

    Example

    obj.once('test', function (a, b) {
        console.log(a + b);
    });
    obj.fire('test', 1, 2); // prints 3 to the console
    obj.fire('test', 1, 2); // not going to get handled

restore

  • restore(uuid, callback?): void

  • Restore anchor using persistent UUID.

    Parameters

    • uuid: string

      UUID string associated with persistent anchor.

    • Optionalcallback: XrAnchorCreateCallback

      Callback to fire when anchor was created or failed to be created.

    Returns void

    Example

    // restore an anchor using uuid string
    app.xr.anchors.restore(uuid, function (err, anchor) {
        if (!err) {
            // new anchor has been created
        }
    });

    Example

    // restore all available persistent anchors
    const uuids = app.xr.anchors.uuids;
    for(let i = 0; i < uuids.length; i++) {
        app.xr.anchors.restore(uuids[i]);
    }

Events

StaticEVENT_ADD

EVENT_ADD: string = 'add'

Fired when a new XrAnchor is added. The handler is passed the XrAnchor that was added.

Example

app.xr.anchors.on('add', (anchor) => {
    console.log('Anchor added');
});

StaticEVENT_AVAILABLE

EVENT_AVAILABLE: string = 'available'

Fired when anchors become available.

Example

app.xr.anchors.on('available', () => {
    console.log('Anchors are available');
});

StaticEVENT_DESTROY

EVENT_DESTROY: string = 'destroy'

Fired when an XrAnchor is destroyed. The handler is passed the XrAnchor that was destroyed.

Example

app.xr.anchors.on('destroy', (anchor) => {
    console.log('Anchor destroyed');
});

StaticEVENT_ERROR

EVENT_ERROR: string = 'error'

Fired when an anchor failed to be created. The handler is passed an Error object.

Example

app.xr.anchors.on('error', (err) => {
    console.error(err.message);
});

StaticEVENT_UNAVAILABLE

EVENT_UNAVAILABLE: string = 'unavailable'

Fired when anchors become unavailable.

Example

app.xr.anchors.on('unavailable', () => {
    console.log('Anchors are unavailable');
});

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