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PositionSensorVRDevice.getState()

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Obsolete
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The getState() method of the PositionSensorVRDevice interface returns the current state of the position sensor for the current frame (e.g. within the current window.requestAnimationFrame callback) or for the previous frame, contained with a VRPositionState object. This is the method you'd normally want to use, versus PositionSensorVRDevice.getImmediateState.

Syntax

var myPositionState = PositionSensorVRDevice.getState();

Parameters

None.

Returns

A VRPositionState object.

Examples

The following example is taken from our positionsensorvrdevice demo, which uses the WebVR API to update the view of a simple 2D canvas scene on each frame of a requestAnimationFrame loop.

function setView() {
  var posState = gPositionSensor.getState();
  if(posState.hasPosition) {
    posPara.textContent = 'Position: x' + roundToTwo(posState.position.x) + " y"
                                + roundToTwo(posState.position.y) + " z"
                                + roundToTwo(posState.position.z);
    xPos = -posState.position.x * WIDTH * 2;
    yPos = posState.position.y * HEIGHT * 2;
    if(-posState.position.z > 0.01) {
      zPos = -posState.position.z;
    } else {
      zPos = 0.01;
    }
  }

  if(posState.hasOrientation) {
    orientPara.textContent = 'Orientation: x' + roundToTwo(posState.orientation.x) + " y"
                                + roundToTwo(posState.orientation.y) + " z"
                                + roundToTwo(posState.orientation.z);
    xOrient = posState.orientation.x * WIDTH;
    yOrient = -posState.orientation.y * HEIGHT * 2;
    zOrient = posState.orientation.z * 180;

  }
}

Here we are grabbing a VRPositionState object using getState() and storing it in posState. We then check to make sure that position and orientation info is present in the current frame using VRPositionState.hasPosition and VRPositionState.hasOrientation (these return null if, for example the head mounted display is turned off or not pointing at the position sensor, which would cause an error.)

We then output the x, y and z position and orientation values for informational purposes, and use those values to update the xPos, yPos, zPos, xOrient, yOrient, and zOrient variables, which are used to update the scene rendering on each frame.

Specifications

Specification Status Comment
WebVR
The definition of 'PositionSensorVRDevice' in that specification.
Editor's Draft Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support (Yes)[1] 39 (39)[2] No support No support No support
Feature Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile Chrome for Android
Basic support No support 39.0 (39)[2]
44.0 (44)[3]
No support No support No support No support No support
  • [1] The support in Chrome is currently experimental. To find information on Chrome's WebVR implementation status including supporting builds, check out Bringing VR to Chrome by Brandon Jones.
  • [2] The support for this feature is currently disabled by default in Firefox. To enable WebVR support in Firefox Nightly/Developer Edition, you can go to about:config and enable the dom.vr* prefs. A better option however is to install the WebVR Enabler Add-on, which does this for you and sets up other necessary parts of the environment.
  • [3] The dom.vr* prefs are enabled by default at this point, in Nightly/Aurora editions.

See also

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