XRPose: emulatedPosition property
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
The emulatedPosition
read-only attribute of the
XRPose
interface is a Boolean value indicating whether or not both the
position
component of the pose's
transform
is directly taken from the XR device, or
it's simulated or computed based on other sources.
Value
A Boolean which is true
if the pose's position is computed based on
estimates or is derived from sources other than direct sensor data. If the position is
precisely based on direct sensor inputs, the value is false
.
Usage notes
There are two basic categories of XR tracking systems. A basic XR headset provides
three degrees of freedom (3DoF), tracking the pitch, yaw, and roll of the user's head.
No information is available about movement forward, backward, or to the sides. Any such
data is taken from other sources, such as keyboard or mouse inputs or game controllers.
As such, the position is considered to be emulated, so the emulatedPosition
property is true
.
Contrariwise, XR devices which can also track movement forward and backward as well as
laterally—six degree of freedom (6DoF) devices—don't require any information from other
sources to determine the user's position, so the value of emulatedPosition
is false
.
The same notion applies not just to the user's head, but to any object. A hand
controller that can directly report its position would have a value of
false
for this property as well. If its position is computed as an offset
from another object (such as by basing it off the model representing the user's body),
then this value is true
.
This information is important because devices whose position is emulated are prone to their offset drifting relative to the real world space over time. This is because emulating a position based on accelerometer inputs and models tends to introduce minor errors which accumulate over time.
Specifications
Specification |
---|
WebXR Device API # dom-xrpose-emulatedposition |
Browser compatibility
BCD tables only load in the browser