XRSession: requestHitTestSource() method

{{APIRef("WebXR Device API")}}{{SeeCompatTable}}{{SecureContext_Header}}

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

Syntax

requestHitTestSource(options)

Parameters

• options
  • : An object containing configuration options, specifically:
    • space
      • : The {{domxref("XRSpace")}} that will be tracked by the hit test source.
    • entityTypes {{Optional_Inline}}
      • : An {{jsxref("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_Inline}}
      • : The {{domxref("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 {{jsxref("Promise")}} that resolves with an {{domxref("XRHitTestSource")}} object.

Exceptions

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

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

Examples

Requesting a hit test source

To request a hit test source, start an {{domxref("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 {{domxref("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
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("XRSession.requestHitTestSourceForTransientInput()")}}