PositionSensorVRDevice.getImmediateState()
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This feature is obsolete.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 getImmediateState()
method of the VRDevice
interface returns the current instantaneous position sensor state. This is intended to only be used rarely, for certain special uses, for example sampling the immediate position of a hand orientation sensor — or at least it will be, in the future.
For most standard uses, you'll probably want to use PositionSensorVRDevice.getState
instead.
Syntax
var myPositionstate = PositionSensorVRDevice.getImmediateState();
Parameters
None.
Returns
A VRPositionState
object.
Examples
Our positionsensorvrdevice demo uses the WebVR API to update the view of a simple 2D canvas
scene on each frame of a requestAnimationFrame
loop. The main function that updates the view data is as follows:
function setView() { var posState = gPositionSensor.getImmediateState(); 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 getImmediateState()
and storing it in posState
(the actual live demo uses getState()
, but both seem to do the same thing currently.) 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 thedom.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
- WebVR API homepage.
- MozVr.com — demos, downloads, and other resources from the Mozilla VR team.
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/positionsensorvrdevice/getimmediatestate