Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
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 VRPose object. This is the method you'd normally want to use, vs. PositionSensorVRDevice.getImmediateState.
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 VRPose 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 VRPose.hasPosition and VRPose.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.
