The WebXR Experience Helpers


Introduction

In order to simplify development for WebXR we offer a WebXR helper that will initialize WebXR automatically for you and provide an environment with which you can develop your AR and VR experiences. Fully configurable, the WebXR experience helper is very flexible and easy to use.

We offer a basic set of functionalities with the WebXR experience helper, and offer a full XR experience, including UI, teleportation and more, with the Default WebXR experience helper.

We recommend using the Default Experience for ease of use, and the Basic Experience Helper when looking for more control over decisions.

Note that you don't have to use the experience helper. Everything can be done outside of those helper on your own.

The basic Experience Helper

Basic usage

The basic experience helper will:

  • Initialize the XR scene
  • Create an XR Camera
  • Initialize the features manager

It also offers help functions to enter and exit the XR session.

The experience helper is promise-based, which technically means its help-functions are mostly asynchronous.

To use the WebXR Experience Helper, first Create one using the static factory:

const xrHelper = await WebXRExperienceHelper.CreateAsync(scene);

If the browser does not support XR an exception will be thrown and will you will need to catch it:

try {
    const xrHelper = await WebXRExperienceHelper.CreateAsync(scene);
} catch (e) {
    // no XR support
}

// or:
WebXRExperienceHelper.CreateAsync(scene).then((xrHelper) => {
    // great success
}, (error) => {
    // no xr...
})

Entering XR

After initializing the XR helper, it is possible to enter an XR session, for example in immersive VR mode:

const sessionManager = await xrHelper.enterXRAsync("immersive-vr", "local-floor" /*, optionalRenderTarget */ );

To read more about session modes ( immersive-vr in this example), and reference type modes ( local-floor ), please read the WebXR specs. The most common scenario is VR in local floor mode, which is the one we are showing here.

If there is an error while creating the experience helper, the console will show it.

Exiting XR

To exit, simply call the exitXRAsync function:

await xrHelper.exitXRAsync();

Observables

The state observable

In this example, the session manager will be initialized if the XR session is ready to use. Alternatively, you can ignore the await and use the state observable of the xr helper:

xrHelper.onStateChangedObservable.add((state) => {
    switch (state) {
        case WebXRState.IN_XR:
            // XR is initialized and already submitted one frame
        case WebXRState.ENTERING_XR:
            // xr is being initialized, enter XR request was made
        case WebXRState.EXITING_XR:
            // xr exit request was made. not yet done.
        case WebXRState.NOT_IN_XR:
            // self explanatory - either our or not yet in XR
    }
})

Pose initialized observable

The onInitialXRPoseSetObservable will trigger all observers when the pose of the camera was set and before the first frame was rendered.

It can be used to define, for example, a height offset (if the ground is not at 0, or if the user starts in a different level):

xrBasicHelper.onInitialXRPoseSetObservable.add((xrCamera) => {
    // floor is at y === 2
    xrCamera.y = 2;
});

Other features

The basic XR experience helper offers direct access to the following:

The WebXR Default Experience

Basic usage of default experience

The default xr experience will:

  • Create a basic experience helper and initialize it
  • Create an HTML UI button to enter XR
  • Init the input source class which will initialize controllers
  • Enable the pointer selection and teleportation features

The simplest way to use the default experience is calling the help function of scene :

var defaultXRExperience = await scene.createDefaultXRExperienceAsync( /* optional configuration options */ );

This is equivalent to:

var defaultXRExperience = await WebXRDefaultExperience.CreateAsync(scene, /* optional configuration options */ )

After calling this and assuming the browser supports XR, you will see the Enter-XR GUI on the bottom right of the screen unless the browser does not support XR. The GUI will not be displayed. To check if the default experience initialized correctly, make sure the baseExperience variable was created:

var defaultXRExperience = await scene.createDefaultXRExperienceAsync( /* optional configuration options */ );
if (!defaultXRExperience.baseExperience) {
    // no xr support
} else {
    // all good, ready to go
}

Configuration options

The default xr experience helper takes an options map for configuration. Everything, including the options itself is optional:

class WebXRDefaultExperienceOptions {
    /**
     * Floor meshes that will be used for teleporting
     */
    public floorMeshes ? : Array < AbstractMesh > ;

    /**
     * Enable or disable default UI to enter XR
     */
    public disableDefaultUI ? : boolean;

    /**
     * optional configuration for the output canvas
     */
    public outputCanvasOptions ? : WebXRManagedOutputCanvasOptions;

    /**
     * optional UI options. This can be used among other to change session mode and reference space type
     */
    public uiOptions ? : WebXREnterExitUIOptions;

    /**
     * Disable the controller mesh-loading. Can be used if you want to load your own meshes
     */
    public inputOptions ? : IWebXRInputOptions;

    /**
     * Should teleportation not initialize. defaults to false.
     */
    public disableTeleportation ? : boolean;
}

Check the code documentation for further details.

Pointer selection and teleportation

The default experience initializes both pointer selection (laser pointer and interaction with the meshes in the scene) and teleportation features automatically. If floor meshes are provided in the options, the teleportation will include it when created. If not you can add meshes later or disable it.

To read more about both features, check the Features Manager

To enable / disable the teleport and pointer selection:

// assuming xrHelper initialized correctly!

// disable:
defaultXRExperience.teleportation.detach();
defaultXRExperience.pointerSelection.detach();

// (re)enable:
defaultXRExperience.teleportation.attach();
defaultXRExperience.pointerSelection.attach();

Configuring the GUI

The GUI is the right way to enter and exit the XR experience. Otherwise you can directly use the baseExperience Basic experience helper to enter and exit XR as mentioned above. It defaults to a VR immersive session in local-floor reference mode.

If you want to change the session mode or reference mode (for example to enter an AR session instead of VR):

var defaultXRExperience = await scene.createDefaultXRExperienceAsync({
    uiOptions: {
        sessionMode: 'ar-immersive'
    }
});

Read more about the GUI in the advanced WebXR tutorial

Available Observables

Apart from those you can find in the baseExperience (The Basic XR experience helper) the default experience does not offer any observables.

Further features

The default experience offers direct access to the following:

  • input - initialized WebXRInputSource
  • enterExitUI - initialized GUI
  • renderTarget - The default WebXR render target