Web/API/XRSession/environmentBlendMode

The XRSession interface's read-only environmentBlendMode property identifies if—and to what degree—the computer-generated imagery is overlaid atop the real world. This is used to differentiate between fully-immersive VR sessions and AR sessions which render over a pass-through image of the real world, possibly partially transparently.

The value is a DOMString which contains one of the values defined by the XREnvironmentBlendMode enumerated type.

Important: environmentBlendMode is part of the WebXR Augmented Reality Module, which has not yet reached a stable state. You should use caution when using its features.

Syntax

blendMode = xrSession.environmentBlendMode;

Value

A DOMString whose value is one of the strings found in the enumerated type XREnvironmentBlendMode, defining if—and if so, how—virtual, rendered content is overlaid atop the image of the real world.

Permitted values are:

opaque: The rendered image is drawn without allowing any pass-through imagery. This is primarily used by fully-immersive VR headsets, which totally obscure the surrounding environment, with none of the real world shown to the user at all. The alpha values specified in the XRSession's renderState property's baseLayer field are ignored since the alpha values for the rendered imagery are all treated as being 1.0 (fully opaque).
additive: Primarily used by AR devices with transparent lenses which directly allow reality to pass through to the user's eyes, the additive blending mode is designed to be used in a situation in which the device has no control over the background and its brightness, since that isn't being digitally controlled. All the device can do is add more light to the image; it can't make things get darker. Therefore, black is rendered as fully transparent, and there's no way to make a pixel fully opaque. As with the opaque setting, alpha values specified are ignored and treated as if they were 1.0.
alpha-blend: Used by headsets or goggles which use cameras to capture the real world and display it digitally on the screen or screens used to render the content for the user to see, this offers a way to create an AR presentation using a VR device. Alpha blending can also be used by non-wearable devices that provide AR modes, such as phones or tablets using cameras to capture the real world for use in AR apps. Since the real world is being digitally presented, the brightness of each pixel can be controlled, whether it's reality or the rendered XR image, the user's environment can be blended with the virtual environment with each pixel having its color and brightness precisely controlled.; In this mode, the XRSession's renderState.baseLayer property provides relative weights of the artificial layer during the compositing process. Pixels whose alpha value is 1.0 are rendered fully opaque, totally obscuring the real world, while pixels with an alpha of 1.0 are totally transparent, leaving the surrounding environment to pass through.

Specifications

Specification	Status	Comment
WebXR Augmented Reality ModuleThe definition of 'XRSession.environmentBlendMode' in that specification.	Working Draft	Initial definition.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`environmentBlendMode`	Chrome Full support 79	Edge Full support 79	Firefox No support No	IE No support No	Opera No support No	Safari No support No	WebView Android No support No	Chrome Android Full support 79	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support 11.2

Legend

Full support: Full support
No support: No support

XRSession.environmentBlendMode by Mozilla Contributors is licensed under CC-BY-SA 2.5.