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<!doctype html>
<!--
Copyright 2018 The Immersive Web Community Group
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-->
<html>
<head>
<meta charset='utf-8'>
<meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
<meta name='mobile-web-app-capable' content='yes'>
<meta name='apple-mobile-web-app-capable' content='yes'>
<!-- Origin Trial Token, feature = WebXR Device API (For Chrome M76+), origin = storage.googleapis.com, expires = 2019-07-24 -->
<meta http-equiv="origin-trial" data-feature="WebXR Device API (For Chrome M76+)" data-expires="2019-07-24" content="Ap6io/uhkGK7vXCD+golNnQfj8wJ4so790EzZoqb8YOljMXIBTvBEQFPTHYIz5d/BgtuwZTKOLrmHAOt30f38g8AAABxeyJvcmlnaW4iOiJodHRwczovL3N0b3JhZ2UuZ29vZ2xlYXBpcy5jb206NDQzIiwiZmVhdHVyZSI6IldlYlhSRGV2aWNlTTc2IiwiZXhwaXJ5IjoxNTY0MDA5MzU2LCJpc1N1YmRvbWFpbiI6dHJ1ZX0=">
<title>Barebones WebXR</title>
<link href='css/common.css' rel='stylesheet'></link>
</head>
<body>
<header>
<details open>
<summary>Barebones WebXR</summary>
<p>
This sample demonstrates extremely simple use of WebXR with no library
dependencies. It doesn't render anything exciting, just clears your
headset's display to a slowly changing color to prove it's working.
<a class="back" href="./index.html">Back</a>
</p>
<div id="warning-zone"></div>
<button id="xr-button" class="barebones-button" disabled>XR not found</button>
</details>
</header>
<main style='text-align: center;'>
<p>Click 'Enter XR' to see content</p>
</main>
<script type="module">
// XR globals.
let xrButton = document.getElementById('xr-button');
let xrSession = null;
let xrRefSpace = null;
// WebGL scene globals.
let gl = null;
function checkSupportedState() {
// If the device allows creation of immersive VR sessions, enable the
// button. If the supportsSession request is rejected, then
// disable the button because it means that the desired session mode is
// not supported.
navigator.xr.isSessionSupported('immersive-vr').then((supported) => {
// Updates the button to start an XR session when clicked.
if (supported) {
xrButton.innerHTML = 'Enter XR';
} else {
xrButton.innerHTML = 'XR not found';
}
xrButton.disabled = !supported;
});
}
// Checks to see if WebXR is available. If it is, checks if the desired
// session options are supported both right now and whenever a device is
// added or removed.
function initXR() {
// WebXR API is only available for secure contexts. If the page is using
// an insecure context, add a warning message about this above the
// button.
if (!window.isSecureContext) {
let message = "WebXR unavailable due to insecure context";
document.getElementById("warning-zone").innerText = message;
}
// If WebXR is available on this UA, check if any devices are connected
// that would support an immersive VR session.
if (navigator.xr) {
// Register our click handler.
// In the other WebXR samples, most of the button details are handled
// by XRDeviceButton from js/webxr-button.js.
xrButton.addEventListener('click', onButtonClicked);
// Register for device change events. This indicates that a device has
// been added or removed, which means that whether or not XR is
// supported has likely changed.
navigator.xr.addEventListener('devicechange', checkSupportedState);
// Just in case the devicechange event has already fired, call it now
// as well.
checkSupportedState();
}
}
// Called when the user clicks the button to enter XR. If we don't have a
// session already we'll request one, and if we do we'll end it.
function onButtonClicked() {
if (!xrSession) {
navigator.xr.requestSession('immersive-vr').then(
onSessionStarted,
onRequestSessionError);
} else {
xrSession.end();
}
}
// Called when we've successfully acquired a XRSession. In response we
// will set up the necessary session state and kick off the frame loop.
function onSessionStarted(session) {
xrSession = session;
xrButton.innerHTML = 'Exit XR';
// Listen for the sessions 'end' event so we can respond if the user
// or UA ends the session for any reason.
session.addEventListener('end', onSessionEnded);
// Create a WebGL context to render with, initialized to be compatible
// with the XRDisplay we're presenting to.
let canvas = document.createElement('canvas');
gl = canvas.getContext('webgl', {
xrCompatible: true
});
// Use the new WebGL context to create a XRWebGLLayer and set it as the
// sessions baseLayer. This allows any content rendered to the layer to
// be displayed on the XR Device.
session.updateRenderState({ baseLayer: new XRWebGLLayer(session, gl) });
// Get a reference space, which is required for querying poses. In
// this case a 'local' reference space means that all poses will be
// relative to the location of the user's head at the time this
// reference space is first created.
session.requestReferenceSpace('local').then((refSpace) => {
xrRefSpace = refSpace;
// Inform the session that we're ready to begin drawing.
session.requestAnimationFrame(onXRFrame);
});
}
// Called when the requestSession promise was rejected with an exception.
function onRequestSessionError(ex) {
alert("Failed to start immersive VR session.");
console.error(ex.message);
}
// Called when the user clicks the 'Exit XR' button. In response we end
// the session.
function onEndSession(session) {
session.end();
}
// Called either when the user has explicitly ended the session (like in
// onEndSession()) or when the UA has ended the session for any reason.
// At this point the session object is no longer usable and should be
// discarded.
function onSessionEnded(event) {
xrSession = null;
xrButton.innerHTML = 'Enter VR';
// In this simple case discard the WebGL context too, since we're not
// rendering anything else to the screen with it.
gl = null;
}
// Called every time the XRSession requests that a new frame be drawn.
function onXRFrame(t, frame) {
let session = frame.session;
// There are a few advantages to requesting the next frame immediately
// instead of at the end of this function.
// 1) It's less likely to forget to call requestAnimationFrame in cases
// when onXRFrame has more complicated control flow.
// 2) If an exception is thrown later in this function, the render loop
// will still continue.
session.requestAnimationFrame(onXRFrame);
// Get the viewer pose relative to the reference space we created
// earlier.
let pose = frame.getViewerPose(xrRefSpace);
// Getting the pose may fail if, for example, tracking is lost. So we
// have to check to make sure that we got a valid pose before attempting
// to render with it. If not, in this case we'll just leave the
// framebuffer cleared, so tracking loss means the scene will simply
// disappear.
if (pose) {
// If we do have a valid pose, bind the WebGL layer's framebuffer,
// which is where any content to be displayed on the XR Device must be
// rendered.
gl.bindFramebuffer(gl.FRAMEBUFFER, session.renderState.baseLayer.framebuffer);
// Update the clear color so that we can observe the color in the
// headset changing over time.
let time = Date.now();
gl.clearColor(Math.cos(time / 2000), Math.cos(time / 4000), Math.cos(time / 6000), 1.0);
// Clear the framebuffer
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// Normally you'd loop through each of the views reported by the frame
// and draw them into the corresponding viewport here, but we're
// keeping this sample slim so we're not bothering to draw any
// geometry.
/*for (let view of pose.views) {
let viewport = session.renderState.baseLayer.getViewport(view);
gl.viewport(viewport.x, viewport.y,
viewport.width, viewport.height);
// Draw something.
}*/
}
}
// Start the XR application.
initXR();
</script>
</body>
</html>
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