XREnvironmentBlendMode

The WebXR API's enumerated type XREnvironmentBlendMode defines strings used to identify if and how to blend the rendered virtual content with the real world. Its values are used by the XRSession interface's environmentBlendMode property.

Values

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 Device API
The definition of 'XREnvironmentBlendMode' in that specification.
Working Draft Initial definition.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
XREnvironmentBlendMode
Experimental
Chrome Full support 79Edge No support NoFirefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support 79Chrome Android Full support 79Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android No support No
additiveChrome Full support 79Edge No support NoFirefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support 79Chrome Android Full support 79Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android No support No
alpha-blendChrome Full support 79Edge No support NoFirefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support 79Chrome Android Full support 79Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android No support No
opaqueChrome Full support 79Edge No support NoFirefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android Full support 79Chrome Android Full support 79Firefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android No support No

Legend

Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.