Engine API Reference - v2.6.1
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    Class XrHitTest

    The Hit Test interface allows initiating hit testing against real-world geometry from various sources: the view, input sources, or an arbitrary ray in space. Results reflect the underlying AR system's understanding of the real world.

    Hierarchy (View Summary)

    Index

    Properties

    sources

    Accessors

    available supported

    Methods

    fire hasEvent off on once start

    Events

    EVENT_ADD EVENT_AVAILABLE EVENT_ERROR EVENT_REMOVE EVENT_RESULT EVENT_UNAVAILABLE

    Properties

    sources: XrHitTestSource[] = []

    List of active XrHitTestSource.

    Accessors

    • get available(): boolean

      True if Hit Test is available. This information is available only when the session has started.

      Returns boolean

    Methods

    • 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.

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

    • 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.

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

    • 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: any

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

      Returns EventHandler

      Self for chaining.

      const handler = () => {};
      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

    • 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: any = ...

        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.

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

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

    • 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: any = ...

        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.
      obj.once('test', (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

    • Attempts to start hit test with provided reference space.

      Parameters

      • Optionaloptions: {
            callback?: XrHitTestStartCallback;
            entityTypes?: string[];
            offsetRay?: Ray;
            profile?: string;
            spaceType?: string;
        } = {}

        Optional object for passing arguments.

        • Optionalcallback?: XrHitTestStartCallback

          Optional callback function called once hit test source is created or failed.

        • OptionalentityTypes?: string[]

          Optional list of underlying entity types against which hit tests will be performed. Defaults to [ XRTRACKABLE_PLANE ]. Can be any combination of the following:

          • XRTRACKABLE_POINT: Point - indicates that the hit test results will be computed based on the feature points detected by the underlying Augmented Reality system.
          • XRTRACKABLE_PLANE: Plane - indicates that the hit test results will be computed based on the planes detected by the underlying Augmented Reality system.
          • XRTRACKABLE_MESH: Mesh - indicates that the hit test results will be computed based on the meshes detected by the underlying Augmented Reality system.
        • OptionaloffsetRay?: Ray

          Optional ray by which hit test ray can be offset.

        • Optionalprofile?: string

          if hit test source meant to match input source instead of reference space, then name of profile of the XrInputSource should be provided.

        • OptionalspaceType?: string

          Reference space type. Defaults to XRSPACE_VIEWER. Can be one of the following:

          • XRSPACE_VIEWER: Viewer - hit test will be facing relative to viewers space.
          • XRSPACE_LOCAL: Local - represents a tracking space with a native origin near the viewer at the time of creation.
          • XRSPACE_LOCALFLOOR: Local Floor - represents a tracking space with a native origin at the floor in a safe position for the user to stand. The y axis equals 0 at floor level. Floor level value might be estimated by the underlying platform.
          • XRSPACE_BOUNDEDFLOOR: Bounded Floor - represents a tracking space with its native origin at the floor, where the user is expected to move within a pre-established boundary.
          • XRSPACE_UNBOUNDED: Unbounded - represents a tracking space where the user is expected to move freely around their environment, potentially long distances from their starting point.

      Returns void

      // start hit testing from viewer position facing forwards
      app.xr.hitTest.start({
          spaceType: pc.XRSPACE_VIEWER,
          callback: function (err, hitTestSource) {
              if (err) return;
              hitTestSource.on('result', function (position, rotation) {
                  // position and rotation of hit test result
              });
          }
      });

      // start hit testing using an arbitrary ray
      const ray = new pc.Ray(new pc.Vec3(0, 0, 0), new pc.Vec3(0, -1, 0));
      app.xr.hitTest.start({
          spaceType: pc.XRSPACE_LOCAL,
          offsetRay: ray,
          callback: function (err, hitTestSource) {
              // hit test source that will sample real world geometry straight down
              // from the position where AR session started
          }
      });

      // start hit testing for touch screen taps
      app.xr.hitTest.start({
          profile: 'generic-touchscreen',
          callback: function (err, hitTestSource) {
              if (err) return;
              hitTestSource.on('result', function (position, rotation, inputSource) {
                  // position and rotation of hit test result
                  // that will be created from touch on mobile devices
              });
          }
      });

    Events

    EVENT_ADD: string = 'add'

    Fired when new XrHitTestSource is added to the list. The handler is passed the XrHitTestSource object that has been added.

    app.xr.hitTest.on('add', (hitTestSource) => {
        // new hit test source is added
    });
    EVENT_AVAILABLE: string = 'available'

    Fired when hit test becomes available.

    app.xr.hitTest.on('available', () => {
        console.log('Hit Testing is available');
    });
    EVENT_ERROR: string = 'error'

    Fired when failed create hit test source. The handler is passed the Error object.

    app.xr.hitTest.on('error', (err) => {
        console.error(err.message);
    });
    EVENT_REMOVE: string = 'remove'

    Fired when XrHitTestSource is removed to the list. The handler is passed the XrHitTestSource object that has been removed.

    app.xr.hitTest.on('remove', (hitTestSource) => {
        // hit test source is removed
    });
    EVENT_RESULT: string = 'result'

    Fired when hit test source receives new results. It provides transform information that tries to match real world picked geometry. The handler is passed the XrHitTestSource that produced the hit result, the Vec3 position, the Quat rotation and the XrInputSource (if it is a transient hit test source).

    app.xr.hitTest.on('result', (hitTestSource, position, rotation, inputSource) => {
        target.setPosition(position);
        target.setRotation(rotation);
    });
    EVENT_UNAVAILABLE: string = 'unavailable'

    Fired when hit test becomes unavailable.

    app.xr.hitTest.on('unavailable', () => {
        console.log('Hit Testing is unavailable');
    });

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