VRLayerInit.rightBounds

The rightBounds property of the VRLayerInit interface (dictionary) defines the right texture bounds of the canvas whose contents will be presented by the VRDisplay.

var myVRLayerInit = { };
myVRLayerInit.rightBounds = [0.5, 0.0, 0.5, 1.0];

An array of four floating point values, which can take values from 0.0–1.0:

1. The left offset of the bounds.
2. The top offset of the bounds.
3. The width of the bounds.
4. The height of the bounds.

If leftBounds is not specified in the dictionary, the default value used is [0.5, 0.0, 0.5, 1.0].

// currently returns an empty array
var layers = vrDisplay.getLayers();

if(navigator.getVRDisplays) {
  console.log('WebVR 1.1 supported');
  // Then get the displays attached to the computer
  navigator.getVRDisplays().then(function(displays) {
    // If a display is available, use it to present the scene
    if(displays.length > 0) {
      vrDisplay = displays[0];
      console.log('Display found');
      // Starting the presentation when the button is clicked: It can only be called in response to a user gesture
      btn.addEventListener('click', function() {
        vrDisplay.requestPresent([{ source: canvas }]).then(function() {
          console.log('Presenting to WebVR display');

          // Here it returns an array of VRLayerInit objects
          var layers = vrDisplay.getLayers();

          ...
        });
      });
    }
  });
}

VRLayerInit objects look something like this:

{
  leftBounds : [ ... ],
  rightBounds: [ ... ],
  source: canvasReference
}

• WebVR API homepage
• https://mixedreality.mozilla.org/ — demos, downloads, and other resources from the Mozilla VR team.