XRSession: requestHitTestSource() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The requestHitTestSource() method of the XRSession interface returns a Promise that resolves with an XRHitTestSource object that can be passed to XRFrame.getHitTestResults().

Syntax

requestHitTestSource(options)

Parameters

options

An object containing configuration options, specifically:

space

The XRSpace that will be tracked by the hit test source.

entityTypes Optional

An Array specifying the types of entities to be used for hit test source creation. If no entity type is specified, the array defaults to a single element with the plane type. Possible types:

point: Compute hit test results based on characteristic points detected.
plane: Compute hit test results based on real-world planes detected.
mesh: Compute hit test results based on meshes detected.

offsetRay Optional

The XRRay object that will be used to perform hit test. If no XRRay object has been provided, a new XRRay object is constructed without any parameters.

Return value

A Promise that resolves with an XRHitTestSource object.

Exceptions

Rather than throwing true exceptions, requestHitTestSource() rejects the returned promise with a DOMException, specifically, one of the following:

NotSupportedError DOMException: Thrown if hit-test is not an enabled feature in XRSystem.requestSession().
InvalidStateError DOMException: Thrown if the session has already ended.
NotAllowedError DOMException: Thrown if there is an unreasonable amount of requests. Some user agents might limit usage for privacy reasons.

To request a hit test source, start an XRSession with the hit-test session feature enabled. Next, configure the hit test source and store it for later use in the frame loop and call XRFrame.getHitTestResults() to obtain the result.

const xrSession = navigator.xr.requestSession("immersive-ar", {
  requiredFeatures: ["local", "hit-test"],
});

let hitTestSource = null;

xrSession
  .requestHitTestSource({
    space: viewerSpace, // obtained from xrSession.requestReferenceSpace("viewer");
    offsetRay: new XRRay({ y: 0.5 }),
  })
  .then((viewerHitTestSource) => {
    hitTestSource = viewerHitTestSource;
  });

// frame loop
function onXRFrame(time, xrFrame) {
  let hitTestResults = xrFrame.getHitTestResults(hitTestSource);

  // do things with the hit test results
}