VRDisplay.getLayers() - Web APIs 编辑

Experimental

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The getLayers() method of the VRDisplay interface returns the layers currently being presented by the VRDisplay.

Syntax

var myLayers = vrDisplayInstance.getLayers();

Parameters

None.

Return value

If the VRDevice is presenting, this method returns an array of the VRLayerInit objects currently being presented (this will currently be one, as VRDisplayCapabilities.maxLayers is currently always 1). If the VRDevice is not presenting, this method returns an empty array.

Examples

// 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
}

Note: The canvasReference refers to the <canvas> element itself, not the WebGL context associated with the canvas. The other two members are arrays

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• WebVR API homepage
• MozVr.com — demos, downloads, and other resources from the Mozilla VR team.