     // Loop through each of the views reported by the frame and draw them
        // into the corresponding viewport.
        for (let view of pose.views) {
          let viewport = glLayer.getViewport(view);
          gl.viewport(viewport.x, viewport.y,
            viewport.width, viewport.height);

          // Draw this view of the scene. What happens in this function really
          // isn't all that important. What is important is that it renders
          // into the XRWebGLLayer's framebuffer, usin