XRViewerPose.views

The read-only XRViewerPose property views returns an array which contains every XRView which must be rendered in order to fully represent the scene from the viewpoint defined by the viewer pose. For monoscopic devices, this array contains a single view.

Stereo views require two views to render properly, with the left eye's view having its eye set to the string left and the right eye's view a value of right.

let viewList = xrViewerPose.views;

An array of XRView objects, one for each view available as part of the scene for the current viewer pose. This array's length may potentially vary over the lifetime of the XRSession (for example, if the viewer enables or disables stereo mode on their XR output device).

In this example—part of the code to render an XRFrame, getViewerPose() is called to get an XRViewerPose using the same reference space the code is using as its base reference space. If a valid pose is returned, the frame is rendered by clearing the backbuffer and then rendering each of the views in the pose; these are most likely the views for the left and right eyes.

let pose = frame.getViewerPose(xrReferenceSpace);

if (pose) {
  let glLayer = xrSession.renderState.baseLayer;

  gl.bindFrameBuffer(gl.FRAMEBUFFER, glLayer.framebuffer);
  gl.clearColor(0, 0, 0, 1);
  gl.clearDepth(1);
  gl.clear(gl.COLOR_BUFFER_BIT, gl.DEPTH_BUFFER_BIT);

  for (let view of pose.views) {
    let viewport = glLayer.getViewport(view);
    gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height);

    /* render the scene for the eye view.eye */
  }
}

Passing each view to getViewport() returns the WebGL viewport to apply in order to cause the rendered output to be positioned correctly in the framebuffer for renderijng to the corresponding eye on the output device.

This code is derived from Drawing a frame in Movement, orientation, and motion: A WebXR example. You can see more context and see much more on that page.

• WebXR Device API
• Movement, orientation, and motion