XRPose

XRPose is a WebXR API interface representing a position and orientation in the 3D space, relative to the XRSpace within which it resides. The XRSpace—which is either an XRReferenceSpace or an XRBoundedReferenceSpace—defines the coordinate system used for the pose and, in the case of an XRViewerPose, its underlying views.

To obtain the XRPose for the XRSpace used as the local coordinate system of an object, call XRFrame.getPose(), specifying that local XRSpace and the space to which you wish to convert:

thePose = xrFrame.getPose(localSpace, baseSpace);

The pose for a viewer (or camera) is represented by the XRViewerPose subclass of XRPose. This is obtained using XRFrame.getViewerPose() instead of getPose(), specifying a reference space which has been adjusted to position and orient the node to provide the desired viewing position and angle:

viewerPose = xrFrame.getViewerPose(adjReferenceSpace);

Here, adjReferenceSpace is a reference space which has been updated using the base frame of reference for the frame and any adjustments needed to position the viewer based on movement or rotation which is being supplied from a source other than the XR device, such as keyboard or mouse inputs.

See the article Movement, orientation, and motion for further details and an example with thorough explanations of what's going on.