XRWebGLSubImage: imageIndex property

Limited availability

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

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

The read-only imageIndex property of the XRWebGLSubImage interface is a number representing the offset into the texture array if the layer was requested with texture-array; null otherwise.

Value

A number or null if the layer wasn't requested with texture-array.

Using imageIndex

The imageIndex property can be passed WebGL2RenderingContext.framebufferTextureLayer() to attach the depth and color textures to a framebuffer with the correct layer index.

js
const xrGlBinding = new XRWebGLBinding(xrSession, gl);
const layer = xrGlBinding.createProjectionLayer({
  textureType: "texture-array",
});
const framebuffer = gl.createFramebuffer();

xrSession.updateRenderState({ layers: [layer] });
xrSession.requestAnimationFrame(onXRFrame);

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

  gl.bindFramebuffer(gl.FRAMEBUFFER, framebuffer);
  const viewport = xrGlBinding.getSubImage(layer, xrFrame).viewport;
  gl.viewport(viewport.x, viewport.y, viewport.width, viewport.height);

  for (const view in xrViewerPose.views) {
    const subImage = xrGlBinding.getViewSubImage(layer, view);
    gl.framebufferTextureLayer(
      gl.FRAMEBUFFER,
      gl.COLOR_ATTACHMENT0,
      subImage.colorTexture,
      0,
      subImage.imageIndex,
    );
    gl.framebufferTextureLayer(
      gl.FRAMEBUFFER,
      gl.DEPTH_ATTACHMENT,
      subImage.depthStencilTexture,
      0,
      subImage.imageIndex,
    );

    // Render from the viewpoint of xrView
  }
}

Specifications

Specification
WebXR Layers API Level 1
# dom-xrwebglsubimage-imageindex

Browser compatibility

BCD tables only load in the browser

See also