XRWebGLBinding: getSubImage() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

experimental technology
Check the Browser compatibility table carefully before using this in production.

The getSubImage() method of the XRWebGLSubImage object representing the WebGL texture to render.

Syntax

getSubImage(layer, frame)
getSubImage(layer, frame, eye)

Parameters

layer

The XRWebGLBinding.getViewSubImage() for rendering projection layers).

frame

The XRFrame frame to use for rendering.

eye Optional

An optional XRView.eye indicating which view's eye to use for rendering. Possible values:

left: The XRView represents the point-of-view of the viewer's left eye.
right: The view represents the viewer's right eye.
none: The view describes a monoscopic view, or the view otherwise doesn't represent a particular eye's point-of-view. Defaults to none.

Return value

A TypeError is thrown,

if layer is not in the session's layer array.
if layer is a XRProjectionLayer.
if the layer's layout property is default.
if the layer's layout property is stereo and eye is none.

Examples

Rendering an `XRQuadLayer`

The following example renders an XRQuadLayer.

const xrGlBinding = new XRWebGLBinding(xrSession, gl);
const quadLayer = xrGlBinding.createQuadLayer({
  space: xrReferenceSpace,
  viewPixelWidth: 512,
  viewPixelHeight: 512,
});

/ Position 2 meters away from the origin with a width and height of 1.5 meters
quadLayer.transform = new XRRigidTransform({ z: -2 });
quadLayer.width = 1.5;
quadLayer.height = 1.5;

const framebuffer = gl.createFramebuffer();
xrSession.updateRenderState({ layers: [quadLayer] });
xrSession.requestAnimationFrame(onXRFrame);

function onXRFrame(time, xrFrame) {
  xrSession.requestAnimationFrame(onXRFrame);

  gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
  let subImage = xrGlBinding.getSubImage(quadLayer, xrFrame);
  gl.framebufferTexture2D(
    gl.FRAMEBUFFER,
    gl.COLOR_ATTACHMENT0,
    subImage.colorTexture,
    0,
  );
  let viewport = subImage.viewport;
  gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height);

  / Render content for the quad layer
}

Specifications

Specification
WebXR Layers API Level 1 # dom-xrwebglbinding-getsubimage