XRBoundedReferenceSpace: boundsGeometry property
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
The read-only XRBoundedReferenceSpace
property boundsGeometry
is an array of
DOMPointReadOnly
objects which specifies the points making up a polygon
inside which the viewer is allowed to move. Each point is treated as a
two-dimensional point, and must be located at ground level (that is,
its y
coordinate must be 0).
This boundary is typically configured by the user, using the software that controls their XR hardware. This may be done by walking the border of the space they wish to use, or by drawing the shape of their room using their XR input device. Theoretically, a more advanced system might use sensors or other detection methods to determine the bounds of a dedicated XR room (notice how we carefully don't call it a holodeck?).
Value
The boundsGeometry
property is an array of DOMPointReadOnly
objects, each of which defines one vertex in a polygon inside which the viewer is
required to remain. Each point must be at floor level, with
its y
coordinate's value set to 0. Additionally, the value
of w
is always 1 in every point in the array. Additionally, the
points must be listed in clockwise order.
Each entry in boundsGeometry
is equal to an entry in the list of native
bounds geometry points for the room, premultiplied by the inverse of the origin offset.
In other words, the bounds are the physical limitations of the available space, shifted
so that the reference space's bounds points are all defined relative to the
XRBoundedReferenceSpace
's effective origin.
Usage notes
Bounded reference spaces always have their origin located at ground level,
where y
is 0. As a general rule, with the origin
for x
and z
located in or near the center of the space, and
with the orientation set facing in a logical forward direction, as appropriate for the
underlying platform or XR hardware.
In order to reduce the risk of the room boundaries being used for fingerprinting
purposes, each point in the boundsGeometry
array may be rounded or adjusted
by some amount. The specification recommends that browsers shift the points to the
nearest 5 centimeters (while avoiding going outside the physical limitations of the
hardware).
Boundary size
XRBoundedReferenceSpace
is not intended to be used for very large bounded
areas. Instead, it's meant to be used for one-room spaces with no more than around 15
meters of available movement space in any direction from the native origin. That said,
the bounds extend upward indefinitely, since the bounds are defined in only two
dimensions.
If you need to create a multi-room space, or a space which is very large or needs to
have varying floor levels, you should instead use an unbounded
XRReferenceSpace
and enforce the bounds on your own, as appropriate.
Boundary shape
The shape defined by boundsGeometry
may be as simple as a square or as
complex as is needed, potentially including concave and/or convex sections. However,
you can't represent spaces with uneven floor levels
using XRBoundedReferenceSpace
. The ground is always
at y
= 0.
It's important that your content not be designed to require the user to exit the bounds
specified by boundsGeometry
. However, if the user's surroundings permit
them to move in such a way as to exit the defined bounds, your content must be able to
gracefully handle the situation, which is not considered an error condition.
Although some samples render a mesh or other shape to display the bounds to the user, in a real-world application, you shouldn't do this. The browser, however, should provide appropriate warnings to the user about any risks (such as the risk that they might run into a physical wall if they keep moving).
Specifications
Specification |
---|
WebXR Device API # dom-xrboundedreferencespace-boundsgeometry |
Browser compatibility
BCD tables only load in the browser