XRRigidTransform

The XRRigidTransform is a WebXR API interface that represents the 3D geometric transform described by a position and orientation.

XRRigidTransform is used to specify transforms throughout the WebXR APIs, including:

• The offset and orientation relative to the parent reference space to use when creating a new reference space with getOffsetReferenceSpace().
• The transform of an XRView.
• The transform of an XRPose.
• The XRReferenceSpaceEvent event's transform property, as found in the reset event received by an XRReferenceSpace.

Using XRRigidTransform in these places rather than bare arrays that provide the matrix data has an advantage. It automatically computes the inverse of the transform and even caches it making subsequent requests significantly faster.

Constructor

XRRigidTransform()

Creates a new XRRigidTransform object which represents a transform that applies a specified position and/or orientation.

Instance properties

XRRigidTransform.position Read only

A DOMPointReadOnly specifying a 3-dimensional point, expressed in meters, describing the translation component of the transform. The w property is always 1.0.

XRRigidTransform.orientation Read only

A DOMPointReadOnly which contains a unit quaternion describing the rotational component of the transform. As a unit quaternion, its length is always normalized to 1.0.

XRRigidTransform.matrix Read only

Returns the transform matrix in the form of a 16-member Float32Array. See the section Matrix format for how the array is used to represent a matrix.

XRRigidTransform.inverse Read only

Returns a XRRigidTransform which is the inverse of this transform. That is, if applied to an object that had been previously transformed by the original transform, it will undo the transform and return the original object.

Usage notes

When an XRRigidTransform is interpreted, the orientation is always applied to the affected object before the position is applied.

Example

This code snippet creates an XRRigidTransform to specify the offset and orientation in relation to the current reference space to use when creating a new reference space. It then requests the first animation frame callback by calling the session's requestAnimationFrame() method.

xrSession.requestReferenceSpace(refSpaceType).then((refSpace) => {
  xrReferenceSpace = refSpace;
  xrReferenceSpace = xrReferenceSpace.getOffsetReferenceSpace(
    new XRRigidTransform(viewerStartPosition, cubeOrientation),
  );
  animationFrameRequestID = xrSession.requestAnimationFrame(drawFrame);
});

Specifications

• WebXR Device API