files/en-us/web/api/xrwebglsubimage/imageindex/index.md
{{APIRef("WebXR Device API")}}{{SeeCompatTable}}
The read-only imageIndex property of the {{domxref("XRWebGLSubImage")}} interface is a number representing the offset into the texture array if the layer was requested with texture-array; null otherwise.
A number or null if the layer wasn't requested with texture-array.
imageIndexThe imageIndex property can be passed {{domxref("WebGL2RenderingContext.framebufferTextureLayer()")}} to attach the depth and color textures to a framebuffer with the correct layer index.
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}}
{{Compat}}