XRWebGLLayer
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The XRWebGLLayer
interface of the WebXR Device API provides a linkage between the WebXR device (or simulated XR device, in the case of an inline session) and a WebGL context used to render the scene for display on the device. In particular, it provides access to the WebGL framebuffer and viewport to ease access to the context.
Although XRWebGLLayer
is currently the only type of framebuffer layer supported by WebGL, it's entirely possible that future updates to the WebXR specification may allow for other layer types and corresponding image sources.
Constructor
XRWebGLLayer()
Experimental-
Creates and returns a new
XRWebGLLayer
object for use by the specifiedXRSession
, using a particularWebGLRenderingContext
orWebGL2RenderingContext
as the destination context.
Instance properties
antialias
Read only Experimental-
A Boolean value indicating whether or not the WebGL context's framebuffer supports anti-aliasing. The specific type of anti-aliasing is determined by the user agent.
fixedFoveation
Experimental-
A number indicating the amount of foveation used by the XR compositor. Fixed Foveated Rendering (FFR) renders the edges of the eye textures at a lower resolution than the center and reduces the GPU load.
framebuffer
Read only Experimental-
Returns a
WebGLFramebuffer
suitable for passing into thebindFrameBuffer()
method. framebufferWidth
Read only Experimental-
Returns the width of the
XRWebGLLayer
's framebuffer. framebufferHeight
Read only Experimental-
Returns the height of the layer's framebuffer.
ignoreDepthValues
Read only Experimental-
A Boolean which Indicates whether or not the WebXR compositor should make use of the contents of the layer's depth buffer while compositing the scene.
Static methods
getNativeFramebufferScaleFactor()
Experimental-
Returns the scaling factor that can be used to scale the resolution of the recommended WebGL framebuffer resolution to the rendering device's native resolution.
Instance methods
getViewport()
Experimental-
Returns a new
XRViewport
instance representing the position, width, and height to which the WebGL context's viewport must be set to contain drawing to the area of the framebuffer designated for the specified view's contents. In this way, for example, the rendering of the left eye's point of view and of the right eye's point of view are each placed into the correct parts of the framebuffer.
Examples
Binding the layer to a WebGL context
This snippet, taken from Drawing a frame in our "Movement and motion" WebXR example, shows how the XRWebGLLayer
is obtained from the XRSession
object's rendering state and is then bound as the current rendering WebGL framebuffer by calling the WebGL bindFrameBuffer()
function.
let glLayer = xrSession.renderState.baseLayer;
gl.bindFrameBuffer(gl.FRAMEBUFFER, glLayer.framebuffer);
Rendering every view in a frame
Each time the GPU is ready to render the scene to the XR device, the XR runtime calls the function you specified when you called the XRSession
method requestAnimationFrame()
to ask to render the frame.
That function receives as input an XRFrame
which encapsulates the data needed to render the frame. This information includes the pose (an XRViewerPose
object) that describes the position and facing direction of the viewer within the scene as well as a list of XRView
objects, each representing one perspective on the scene. In current WebXR implementations, there will never be more than two entries in this list: one describing the position and viewing angle of the left eye and another doing the same for the right.
let pose = xrFrame.getViewerPose(xrReferenceSpace);
if (pose) {
const glLayer = xrSession.renderState.baseLayer;
gl.bindFrameBuffer(gl.FRAMEBUFFER, glLayer.Framebffer);
for (const view of pose.views) {
const viewport = glLayer.getViewport(view);
gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height);
/* Render the view */
}
}
Specifications
Specification |
---|
WebXR Device API # xrwebgllayer-interface |
Browser compatibility
BCD tables only load in the browser
See also
- WebXR Device API
- Getting started with WebGL
WebGLRenderingContext
andWebGL2RenderingContext
- Drawing a frame in our "Movement and motion" WebXR example