WebXR: Added XRButton (#25781)

* Added XRButton.js

* Examples: Updated relevant examples using XRButton.

* WebXRManager: Added setSessionMode().

* WebGLRenderer: Force clear when sessionMode is 'immersive-ar'.

* Clean up.

* WebXRManager: Force alpha: true in layerInit.

* WebGLRenderer: Set state.buffers.color before calling clear() for 'immersive-ar'.

* Fix typo

* WebGLBackground: Handle WebXR sessions environmentBlendMode.

* WebXRManager: Removed setSessionMode().

* XRButton: Revert extra removal.

examples/files.json

@@ -357,14 +357,9 @@
 	],
 	"webxr": [
 		"webxr_ar_cones",
-		"webxr_ar_dragging",
 		"webxr_ar_hittest",
 		"webxr_ar_lighting",
-		"webxr_ar_paint",
 		"webxr_ar_plane_detection",
-		"webxr_vr_ballshooter",
-		"webxr_vr_cubes",
-		"webxr_vr_dragging",
 		"webxr_vr_handinput",
 		"webxr_vr_handinput_cubes",
 		"webxr_vr_handinput_profiles",
@@ -375,12 +370,15 @@
 		"webxr_vr_layers",
 		"webxr_vr_panorama",
 		"webxr_vr_panorama_depth",
-		"webxr_vr_paint",
 		"webxr_vr_rollercoaster",
 		"webxr_vr_sandbox",
-		"webxr_vr_sculpt",
 		"webxr_vr_teleport",
-		"webxr_vr_video"
+		"webxr_vr_video",
+		"webxr_xr_ballshooter",
+		"webxr_xr_cubes",
+		"webxr_xr_dragging",
+		"webxr_xr_paint",
+		"webxr_xr_sculpt"
 	],
 	"games": [
 		"games_fps"

examples/jsm/webxr/XRButton.js

@@ -0,0 +1,198 @@
+class XRButton {
+
+	static createButton( renderer ) {
+
+		const button = document.createElement( 'button' );
+
+		function showStartXR( mode ) {
+
+			let currentSession = null;
+
+			async function onSessionStarted( session ) {
+
+				session.addEventListener( 'end', onSessionEnded );
+
+				await renderer.xr.setSession( session );
+
+				button.textContent = 'STOP XR';
+
+				currentSession = session;
+
+			}
+
+			function onSessionEnded( /*event*/ ) {
+
+				currentSession.removeEventListener( 'end', onSessionEnded );
+
+				button.textContent = 'START XR';
+
+				currentSession = null;
+
+			}
+
+			//
+
+			button.style.display = '';
+
+			button.style.cursor = 'pointer';
+			button.style.left = 'calc(50% - 50px)';
+			button.style.width = '100px';
+
+			button.textContent = 'START XR';
+
+			button.onmouseenter = function () {
+
+				button.style.opacity = '1.0';
+
+			};
+
+			button.onmouseleave = function () {
+
+				button.style.opacity = '0.5';
+
+			};
+
+			button.onclick = function () {
+
+				if ( currentSession === null ) {
+
+					const sessionInit = {
+						optionalFeatures: [
+							'local-floor',
+							'bounded-floor',
+							'hand-tracking',
+							'layers'
+						]
+					};
+
+					navigator.xr.requestSession( mode, sessionInit )
+						.then( onSessionStarted );
+
+				} else {
+
+					currentSession.end();
+
+				}
+
+			};
+
+		}
+
+		function disableButton() {
+
+			button.style.display = '';
+
+			button.style.cursor = 'auto';
+			button.style.left = 'calc(50% - 75px)';
+			button.style.width = '150px';
+
+			button.onmouseenter = null;
+			button.onmouseleave = null;
+
+			button.onclick = null;
+
+		}
+
+		function showXRNotSupported() {
+
+			disableButton();
+
+			button.textContent = 'XR NOT SUPPORTED';
+
+		}
+
+		function showXRNotAllowed( exception ) {
+
+			disableButton();
+
+			console.warn( 'Exception when trying to call xr.isSessionSupported', exception );
+
+			button.textContent = 'XR NOT ALLOWED';
+
+		}
+
+		function stylizeElement( element ) {
+
+			element.style.position = 'absolute';
+			element.style.bottom = '20px';
+			element.style.padding = '12px 6px';
+			element.style.border = '1px solid #fff';
+			element.style.borderRadius = '4px';
+			element.style.background = 'rgba(0,0,0,0.1)';
+			element.style.color = '#fff';
+			element.style.font = 'normal 13px sans-serif';
+			element.style.textAlign = 'center';
+			element.style.opacity = '0.5';
+			element.style.outline = 'none';
+			element.style.zIndex = '999';
+
+		}
+
+		if ( 'xr' in navigator ) {
+
+			button.id = 'XRButton';
+			button.style.display = 'none';
+
+			stylizeElement( button );
+
+			navigator.xr.isSessionSupported( 'immersive-ar' )
+				.then( function ( supported ) {
+
+					if ( supported ) {
+
+						showStartXR( 'immersive-ar' );
+
+					} else {
+
+						navigator.xr.isSessionSupported( 'immersive-vr' )
+							.then( function ( supported ) {
+
+								if ( supported ) {
+
+									showStartXR( 'immersive-vr' );
+
+								} else {
+
+									showXRNotSupported();
+
+								}
+
+							} ).catch( showXRNotAllowed );
+
+					}
+
+				} ).catch( showXRNotAllowed );
+
+			return button;
+
+		} else {
+
+			const message = document.createElement( 'a' );
+
+			if ( window.isSecureContext === false ) {
+
+				message.href = document.location.href.replace( /^http:/, 'https:' );
+				message.innerHTML = 'WEBXR NEEDS HTTPS'; // TODO Improve message
+
+			} else {
+
+				message.href = 'https://immersiveweb.dev/';
+				message.innerHTML = 'WEBXR NOT AVAILABLE';
+
+			}
+
+			message.style.left = 'calc(50% - 90px)';
+			message.style.width = '180px';
+			message.style.textDecoration = 'none';
+
+			stylizeElement( message );
+
+			return message;
+
+		}
+
+	}
+
+}
+
+export { XRButton };