XRWebGLBinding: getSubImage() method

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The getSubImage() method of the XRWebGLBinding interface returns a XRWebGLSubImage object representing the WebGL texture to render.

Syntax

js

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

Parameters

layer

The XRCompositionLayer to use for rendering (can be all types of XRCompositionLayer objects except XRProjectionLayer, see 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.

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 XRWebGLSubImage object.

Exceptions

A TypeError is thrown,

Examples

Rendering an XRQuadLayer

The following example renders an XRQuadLayer.

js

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

Browser compatibility

BCD tables only load in the browser

See also