webvr-polyfill-aframe-051

WebVR Polyfill

A JavaScript implementation of the WebVR spec. This project lets you use WebVR today, without requiring a special browser build. It also lets you view the same content without requiring a virtual reality viewer.

Take a look at basic WebVR samples that use this polyfill.

Implementation

The polyfill decides which VRDisplays to provide, depending on the configuration of your browser. Mobile devices provide the CardboardVRDisplay. Desktop devices use the MouseKeyboardVRDisplay.

CardboardVRDisplay uses DeviceMotionEvents to implement a complementary filter which does sensor fusion and pose prediction to provide orientation tracking. It can also render in stereo mode, and includes mesh-based lens distortion. This display also includes user interface elements in VR mode to make the VR experience more intuitive, including:

• A gear icon to select your VR viewer.
• A back button to exit VR mode.
• An interstitial which only appears in portrait orientation, requesting you switch into landscape orientation (if orientation lock is not available).

MouseKeyboardVRDisplay uses mouse events to allow you to do the equivalent of mouselook. It also uses keyboard arrows keys to look around the scene with the keyboard.

Configuration

The polyfill can be configured and debugged with various options. The following are supported:

WebVRConfig = {
  // Flag to disabled the UI in VR Mode.
  CARDBOARD_UI_DISABLED: false, // Default: false

  // Forces availability of VR mode, even for non-mobile devices.
  FORCE_ENABLE_VR: true, // Default: false.

  // Complementary filter coefficient. 0 for accelerometer, 1 for gyro.
  K_FILTER: 0.98, // Default: 0.98.

  // Flag to disable the instructions to rotate your device.
  ROTATE_INSTRUCTIONS_DISABLED: false, // Default: false.

  // How far into the future to predict during fast motion (in seconds).
  PREDICTION_TIME_S: 0.040, // Default: 0.040.

  // Flag to disable touch panner. In case you have your own touch controls.
  TOUCH_PANNER_DISABLED: false, // Default: true.

  // Enable yaw panning only, disabling roll and pitch. This can be useful
  // for panoramas with nothing interesting above or below.
  YAW_ONLY: true, // Default: false.

  // To disable keyboard and mouse controls, if you want to use your own
  // implementation.
  MOUSE_KEYBOARD_CONTROLS_DISABLED: true, // Default: false.

  // Prevent the polyfill from initializing immediately. Requires the app
  // to call InitializeWebVRPolyfill() before it can be used.
  DEFER_INITIALIZATION: true, // Default: false.

  // Enable the deprecated version of the API (navigator.getVRDevices).
  ENABLE_DEPRECATED_API: true, // Default: false.

  // Scales the recommended buffer size reported by WebVR, which can improve
  // performance.
  BUFFER_SCALE: 0.5, // Default: 0.5.

  // Allow VRDisplay.submitFrame to change gl bindings, which is more
  // efficient if the application code will re-bind its resources on the
  // next frame anyway. This has been seen to cause rendering glitches with
  // THREE.js.
  // Dirty bindings include: gl.FRAMEBUFFER_BINDING, gl.CURRENT_PROGRAM,
  // gl.ARRAY_BUFFER_BINDING, gl.ELEMENT_ARRAY_BUFFER_BINDING,
  // and gl.TEXTURE_BINDING_2D for texture unit 0.
  DIRTY_SUBMIT_FRAME_BINDINGS: true // Default: false.

  // When set to true, this will cause a polyfilled VRDisplay to always be
  // appended to the list returned by navigator.getVRDisplays(), even if that
  // list includes a native VRDisplay.
  ALWAYS_APPEND_POLYFILL_DISPLAY: false,

  // There are versions of Chrome (M58-M60?) where the native WebVR API exists,
  // and instead of returning 0 VR displays when none are detected,
  // `navigator.getVRDisplays()`'s promise never resolves. This results
  // in the polyfill hanging and not being able to provide fallback
  // displays, so set a timeout in milliseconds to stop waiting for a response
  // and just use polyfilled displays.
  // https://bugs.chromium.org/p/chromium/issues/detail?id=727969
  GET_VR_DISPLAYS_TIMEOUT: 1000,
}

Performance

Performance is critical for VR. If you find your application is too sluggish, consider tweaking some of the above parameters. In particular, keeping BUFFER_SCALE at 0.5 (the default) will likely help a lot.

Development

If you'd like to contribute to the webvr-poyfill library, check out the repository and install Node and the dependencies:

git clone https://github.com/googlevr/webvr-polyfill
cd webvr-polyfill
npm install

Development Commands

• npm install: installs the dependencies.
• npm start: auto-builds the module whenever any source changes and serves the example content on http://0.0.0.0:8080/.
• npm run build: builds the module.

License

This program is free software for both commercial and non-commercial use, distributed under the Apache 2.0 License.

Thanks

• Brandon Jones and Vladimir Vukicevic for their work on the WebVR spec.
• Ricardo Cabello for THREE.js.
• Diego Marcos for VREffect and VRControls.
• Dmitriy Kovalev for help with lens distortion correction.