initial commit, 4.5 stable

platform/web/js/engine/config.js

@@ -0,0 +1,378 @@
+/**
+ * An object used to configure the Engine instance based on godot export options, and to override those in custom HTML
+ * templates if needed.
+ *
+ * @header Engine configuration
+ * @summary The Engine configuration object. This is just a typedef, create it like a regular object, e.g.:
+ *
+ * ``const MyConfig = { executable: 'godot', unloadAfterInit: false }``
+ *
+ * @typedef {Object} EngineConfig
+ */
+const EngineConfig = {}; // eslint-disable-line no-unused-vars
+
+/**
+ * @struct
+ * @constructor
+ * @ignore
+ */
+const InternalConfig = function (initConfig) { // eslint-disable-line no-unused-vars
+	const cfg = /** @lends {InternalConfig.prototype} */ {
+		/**
+		 * Whether to unload the engine automatically after the instance is initialized.
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {boolean}
+		 */
+		unloadAfterInit: true,
+		/**
+		 * The HTML DOM Canvas object to use.
+		 *
+		 * By default, the first canvas element in the document will be used is none is specified.
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {?HTMLCanvasElement}
+		 */
+		canvas: null,
+		/**
+		 * The name of the WASM file without the extension. (Set by Godot Editor export process).
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {string}
+		 */
+		executable: '',
+		/**
+		 * An alternative name for the game pck to load. The executable name is used otherwise.
+		 *
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {?string}
+		 */
+		mainPack: null,
+		/**
+		 * Specify a language code to select the proper localization for the game.
+		 *
+		 * The browser locale will be used if none is specified. See complete list of
+		 * :ref:`supported locales <doc_locales>`.
+		 *
+		 * @memberof EngineConfig
+		 * @type {?string}
+		 * @default
+		 */
+		locale: null,
+		/**
+		 * The canvas resize policy determines how the canvas should be resized by Godot.
+		 *
+		 * ``0`` means Godot won't do any resizing. This is useful if you want to control the canvas size from
+		 * javascript code in your template.
+		 *
+		 * ``1`` means Godot will resize the canvas on start, and when changing window size via engine functions.
+		 *
+		 * ``2`` means Godot will adapt the canvas size to match the whole browser window.
+		 *
+		 * @memberof EngineConfig
+		 * @type {number}
+		 * @default
+		 */
+		canvasResizePolicy: 2,
+		/**
+		 * The arguments to be passed as command line arguments on startup.
+		 *
+		 * See :ref:`command line tutorial <doc_command_line_tutorial>`.
+		 *
+		 * **Note**: :js:meth:`startGame <Engine.prototype.startGame>` will always add the ``--main-pack`` argument.
+		 *
+		 * @memberof EngineConfig
+		 * @type {Array<string>}
+		 * @default
+		 */
+		args: [],
+		/**
+		 * When enabled, the game canvas will automatically grab the focus when the engine starts.
+		 *
+		 * @memberof EngineConfig
+		 * @type {boolean}
+		 * @default
+		 */
+		focusCanvas: true,
+		/**
+		 * When enabled, this will turn on experimental virtual keyboard support on mobile.
+		 *
+		 * @memberof EngineConfig
+		 * @type {boolean}
+		 * @default
+		 */
+		experimentalVK: false,
+		/**
+		 * The progressive web app service worker to install.
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {string}
+		 */
+		serviceWorker: '',
+		/**
+		 * @ignore
+		 * @type {Array.<string>}
+		 */
+		persistentPaths: ['/userfs'],
+		/**
+		 * @ignore
+		 * @type {boolean}
+		 */
+		persistentDrops: false,
+		/**
+		 * @ignore
+		 * @type {Array.<string>}
+		 */
+		gdextensionLibs: [],
+		/**
+		 * @ignore
+		 * @type {Array.<string>}
+		 */
+		fileSizes: [],
+		/**
+		 * @ignore
+		 * @type {number}
+		 */
+		emscriptenPoolSize: 8,
+		/**
+		 * @ignore
+		 * @type {number}
+		 */
+		godotPoolSize: 4,
+		/**
+		 * A callback function for handling Godot's ``OS.execute`` calls.
+		 *
+		 * This is for example used in the Web Editor template to switch between project manager and editor, and for running the game.
+		 *
+		 * @callback EngineConfig.onExecute
+		 * @param {string} path The path that Godot's wants executed.
+		 * @param {Array.<string>} args The arguments of the "command" to execute.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(string, Array.<string>)}
+		 */
+		onExecute: null,
+		/**
+		 * A callback function for being notified when the Godot instance quits.
+		 *
+		 * **Note**: This function will not be called if the engine crashes or become unresponsive.
+		 *
+		 * @callback EngineConfig.onExit
+		 * @param {number} status_code The status code returned by Godot on exit.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(number)}
+		 */
+		onExit: null,
+		/**
+		 * A callback function for displaying download progress.
+		 *
+		 * The function is called once per frame while downloading files, so the usage of ``requestAnimationFrame()``
+		 * is not necessary.
+		 *
+		 * If the callback function receives a total amount of bytes as 0, this means that it is impossible to calculate.
+		 * Possible reasons include:
+		 *
+		 * -  Files are delivered with server-side chunked compression
+		 * -  Files are delivered with server-side compression on Chromium
+		 * -  Not all file downloads have started yet (usually on servers without multi-threading)
+		 *
+		 * @callback EngineConfig.onProgress
+		 * @param {number} current The current amount of downloaded bytes so far.
+		 * @param {number} total The total amount of bytes to be downloaded.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(number, number)}
+		 */
+		onProgress: null,
+		/**
+		 * A callback function for handling the standard output stream. This method should usually only be used in debug pages.
+		 *
+		 * By default, ``console.log()`` is used.
+		 *
+		 * @callback EngineConfig.onPrint
+		 * @param {...*} [var_args] A variadic number of arguments to be printed.
+		 */
+		/**
+		 * @ignore
+		 * @type {?function(...*)}
+		 */
+		onPrint: function () {
+			console.log.apply(console, Array.from(arguments)); // eslint-disable-line no-console
+		},
+		/**
+		 * A callback function for handling the standard error stream. This method should usually only be used in debug pages.
+		 *
+		 * By default, ``console.error()`` is used.
+		 *
+		 * @callback EngineConfig.onPrintError
+		 * @param {...*} [var_args] A variadic number of arguments to be printed as errors.
+		*/
+		/**
+		 * @ignore
+		 * @type {?function(...*)}
+		 */
+		onPrintError: function (var_args) {
+			console.error.apply(console, Array.from(arguments)); // eslint-disable-line no-console
+		},
+	};
+
+	/**
+	 * @ignore
+	 * @struct
+	 * @constructor
+	 * @param {EngineConfig} opts
+	 */
+	function Config(opts) {
+		this.update(opts);
+	}
+
+	Config.prototype = cfg;
+
+	/**
+	 * @ignore
+	 * @param {EngineConfig} opts
+	 */
+	Config.prototype.update = function (opts) {
+		const config = opts || {};
+		// NOTE: We must explicitly pass the default, accessing it via
+		// the key will fail due to closure compiler renames.
+		function parse(key, def) {
+			if (typeof (config[key]) === 'undefined') {
+				return def;
+			}
+			return config[key];
+		}
+		// Module config
+		this.unloadAfterInit = parse('unloadAfterInit', this.unloadAfterInit);
+		this.onPrintError = parse('onPrintError', this.onPrintError);
+		this.onPrint = parse('onPrint', this.onPrint);
+		this.onProgress = parse('onProgress', this.onProgress);
+
+		// Godot config
+		this.canvas = parse('canvas', this.canvas);
+		this.executable = parse('executable', this.executable);
+		this.mainPack = parse('mainPack', this.mainPack);
+		this.locale = parse('locale', this.locale);
+		this.canvasResizePolicy = parse('canvasResizePolicy', this.canvasResizePolicy);
+		this.persistentPaths = parse('persistentPaths', this.persistentPaths);
+		this.persistentDrops = parse('persistentDrops', this.persistentDrops);
+		this.experimentalVK = parse('experimentalVK', this.experimentalVK);
+		this.focusCanvas = parse('focusCanvas', this.focusCanvas);
+		this.serviceWorker = parse('serviceWorker', this.serviceWorker);
+		this.gdextensionLibs = parse('gdextensionLibs', this.gdextensionLibs);
+		this.fileSizes = parse('fileSizes', this.fileSizes);
+		this.emscriptenPoolSize = parse('emscriptenPoolSize', this.emscriptenPoolSize);
+		this.godotPoolSize = parse('godotPoolSize', this.godotPoolSize);
+		this.args = parse('args', this.args);
+		this.onExecute = parse('onExecute', this.onExecute);
+		this.onExit = parse('onExit', this.onExit);
+	};
+
+	/**
+	 * @ignore
+	 * @param {string} loadPath
+	 * @param {Response} response
+	 */
+	Config.prototype.getModuleConfig = function (loadPath, response) {
+		let r = response;
+		const gdext = this.gdextensionLibs;
+		return {
+			'print': this.onPrint,
+			'printErr': this.onPrintError,
+			'thisProgram': this.executable,
+			'noExitRuntime': false,
+			'dynamicLibraries': [`${loadPath}.side.wasm`].concat(this.gdextensionLibs),
+			'emscriptenPoolSize': this.emscriptenPoolSize,
+			'instantiateWasm': function (imports, onSuccess) {
+				function done(result) {
+					onSuccess(result['instance'], result['module']);
+				}
+				if (typeof (WebAssembly.instantiateStreaming) !== 'undefined') {
+					WebAssembly.instantiateStreaming(Promise.resolve(r), imports).then(done);
+				} else {
+					r.arrayBuffer().then(function (buffer) {
+						WebAssembly.instantiate(buffer, imports).then(done);
+					});
+				}
+				r = null;
+				return {};
+			},
+			'locateFile': function (path) {
+				if (!path.startsWith('godot.')) {
+					return path;
+				} else if (path.endsWith('.audio.worklet.js')) {
+					return `${loadPath}.audio.worklet.js`;
+				} else if (path.endsWith('.audio.position.worklet.js')) {
+					return `${loadPath}.audio.position.worklet.js`;
+				} else if (path.endsWith('.js')) {
+					return `${loadPath}.js`;
+				} else if (path in gdext) {
+					return path;
+				} else if (path.endsWith('.side.wasm')) {
+					return `${loadPath}.side.wasm`;
+				} else if (path.endsWith('.wasm')) {
+					return `${loadPath}.wasm`;
+				}
+				return path;
+			},
+		};
+	};
+
+	/**
+	 * @ignore
+	 * @param {function()} cleanup
+	 */
+	Config.prototype.getGodotConfig = function (cleanup) {
+		// Try to find a canvas
+		if (!(this.canvas instanceof HTMLCanvasElement)) {
+			const nodes = document.getElementsByTagName('canvas');
+			if (nodes.length && nodes[0] instanceof HTMLCanvasElement) {
+				const first = nodes[0];
+				this.canvas = /** @type {!HTMLCanvasElement} */ (first);
+			}
+			if (!this.canvas) {
+				throw new Error('No canvas found in page');
+			}
+		}
+		// Canvas can grab focus on click, or key events won't work.
+		if (this.canvas.tabIndex < 0) {
+			this.canvas.tabIndex = 0;
+		}
+
+		// Browser locale, or custom one if defined.
+		let locale = this.locale;
+		if (!locale) {
+			locale = navigator.languages ? navigator.languages[0] : navigator.language;
+			locale = locale.split('.')[0];
+		}
+		locale = locale.replace('-', '_');
+		const onExit = this.onExit;
+
+		// Godot configuration.
+		return {
+			'canvas': this.canvas,
+			'canvasResizePolicy': this.canvasResizePolicy,
+			'locale': locale,
+			'persistentDrops': this.persistentDrops,
+			'virtualKeyboard': this.experimentalVK,
+			'godotPoolSize': this.godotPoolSize,
+			'focusCanvas': this.focusCanvas,
+			'onExecute': this.onExecute,
+			'onExit': function (p_code) {
+				cleanup(); // We always need to call the cleanup callback to free memory.
+				if (typeof (onExit) === 'function') {
+					onExit(p_code);
+				}
+			},
+		};
+	};
+	return new Config(initConfig);
+};

platform/web/js/engine/engine.externs.js

@@ -0,0 +1,4 @@
+var Godot;
+var WebAssembly = {};
+WebAssembly.instantiate = function(buffer, imports) {};
+WebAssembly.instantiateStreaming = function(response, imports) {};

platform/web/js/engine/engine.js

@@ -0,0 +1,286 @@
+/**
+ * Projects exported for the Web expose the :js:class:`Engine` class to the JavaScript environment, that allows
+ * fine control over the engine's start-up process.
+ *
+ * This API is built in an asynchronous manner and requires basic understanding
+ * of `Promises <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promises>`__.
+ *
+ * @module Engine
+ * @header Web export JavaScript reference
+ */
+const Engine = (function () {
+	const preloader = new Preloader();
+
+	let loadPromise = null;
+	let loadPath = '';
+	let initPromise = null;
+
+	/**
+	 * @classdesc The ``Engine`` class provides methods for loading and starting exported projects on the Web. For default export
+	 * settings, this is already part of the exported HTML page. To understand practical use of the ``Engine`` class,
+	 * see :ref:`Custom HTML page for Web export <doc_customizing_html5_shell>`.
+	 *
+	 * @description Create a new Engine instance with the given configuration.
+	 *
+	 * @global
+	 * @constructor
+	 * @param {EngineConfig} initConfig The initial config for this instance.
+	 */
+	function Engine(initConfig) { // eslint-disable-line no-shadow
+		this.config = new InternalConfig(initConfig);
+		this.rtenv = null;
+	}
+
+	/**
+	 * Load the engine from the specified base path.
+	 *
+	 * @param {string} basePath Base path of the engine to load.
+	 * @param {number=} [size=0] The file size if known.
+	 * @returns {Promise} A Promise that resolves once the engine is loaded.
+	 *
+	 * @function Engine.load
+	 */
+	Engine.load = function (basePath, size) {
+		if (loadPromise == null) {
+			loadPath = basePath;
+			loadPromise = preloader.loadPromise(`${loadPath}.wasm`, size, true);
+			requestAnimationFrame(preloader.animateProgress);
+		}
+		return loadPromise;
+	};
+
+	/**
+	 * Unload the engine to free memory.
+	 *
+	 * This method will be called automatically depending on the configuration. See :js:attr:`unloadAfterInit`.
+	 *
+	 * @function Engine.unload
+	 */
+	Engine.unload = function () {
+		loadPromise = null;
+	};
+
+	/**
+	 * Safe Engine constructor, creates a new prototype for every new instance to avoid prototype pollution.
+	 * @ignore
+	 * @constructor
+	 */
+	function SafeEngine(initConfig) {
+		const proto = /** @lends Engine.prototype */ {
+			/**
+			 * Initialize the engine instance. Optionally, pass the base path to the engine to load it,
+			 * if it hasn't been loaded yet. See :js:meth:`Engine.load`.
+			 *
+			 * @param {string=} basePath Base path of the engine to load.
+			 * @return {Promise} A ``Promise`` that resolves once the engine is loaded and initialized.
+			 */
+			init: function (basePath) {
+				if (initPromise) {
+					return initPromise;
+				}
+				if (loadPromise == null) {
+					if (!basePath) {
+						initPromise = Promise.reject(new Error('A base path must be provided when calling `init` and the engine is not loaded.'));
+						return initPromise;
+					}
+					Engine.load(basePath, this.config.fileSizes[`${basePath}.wasm`]);
+				}
+				const me = this;
+				function doInit(promise) {
+					// Care! Promise chaining is bogus with old emscripten versions.
+					// This caused a regression with the Mono build (which uses an older emscripten version).
+					// Make sure to test that when refactoring.
+					return new Promise(function (resolve, reject) {
+						promise.then(function (response) {
+							const cloned = new Response(response.clone().body, { 'headers': [['content-type', 'application/wasm']] });
+							Godot(me.config.getModuleConfig(loadPath, cloned)).then(function (module) {
+								const paths = me.config.persistentPaths;
+								module['initFS'](paths).then(function (err) {
+									me.rtenv = module;
+									if (me.config.unloadAfterInit) {
+										Engine.unload();
+									}
+									resolve();
+								});
+							});
+						});
+					});
+				}
+				preloader.setProgressFunc(this.config.onProgress);
+				initPromise = doInit(loadPromise);
+				return initPromise;
+			},
+
+			/**
+			 * Load a file so it is available in the instance's file system once it runs. Must be called **before** starting the
+			 * instance.
+			 *
+			 * If not provided, the ``path`` is derived from the URL of the loaded file.
+			 *
+			 * @param {string|ArrayBuffer} file The file to preload.
+			 *
+			 * If a ``string`` the file will be loaded from that path.
+			 *
+			 * If an ``ArrayBuffer`` or a view on one, the buffer will used as the content of the file.
+			 *
+			 * @param {string=} path Path by which the file will be accessible. Required, if ``file`` is not a string.
+			 *
+			 * @returns {Promise} A Promise that resolves once the file is loaded.
+			 */
+			preloadFile: function (file, path) {
+				return preloader.preload(file, path, this.config.fileSizes[file]);
+			},
+
+			/**
+			 * Start the engine instance using the given override configuration (if any).
+			 * :js:meth:`startGame <Engine.prototype.startGame>` can be used in typical cases instead.
+			 *
+			 * This will initialize the instance if it is not initialized. For manual initialization, see :js:meth:`init <Engine.prototype.init>`.
+			 * The engine must be loaded beforehand.
+			 *
+			 * Fails if a canvas cannot be found on the page, or not specified in the configuration.
+			 *
+			 * @param {EngineConfig} override An optional configuration override.
+			 * @return {Promise} Promise that resolves once the engine started.
+			 */
+			start: function (override) {
+				this.config.update(override);
+				const me = this;
+				return me.init().then(function () {
+					if (!me.rtenv) {
+						return Promise.reject(new Error('The engine must be initialized before it can be started'));
+					}
+
+					let config = {};
+					try {
+						config = me.config.getGodotConfig(function () {
+							me.rtenv = null;
+						});
+					} catch (e) {
+						return Promise.reject(e);
+					}
+					// Godot configuration.
+					me.rtenv['initConfig'](config);
+
+					// Preload GDExtension libraries.
+					if (me.config.gdextensionLibs.length > 0 && !me.rtenv['loadDynamicLibrary']) {
+						return Promise.reject(new Error('GDExtension libraries are not supported by this engine version. '
+							+ 'Enable "Extensions Support" for your export preset and/or build your custom template with "dlink_enabled=yes".'));
+					}
+					return new Promise(function (resolve, reject) {
+						for (const file of preloader.preloadedFiles) {
+							me.rtenv['copyToFS'](file.path, file.buffer);
+						}
+						preloader.preloadedFiles.length = 0; // Clear memory
+						me.rtenv['callMain'](me.config.args);
+						initPromise = null;
+						me.installServiceWorker();
+						resolve();
+					});
+				});
+			},
+
+			/**
+			 * Start the game instance using the given configuration override (if any).
+			 *
+			 * This will initialize the instance if it is not initialized. For manual initialization, see :js:meth:`init <Engine.prototype.init>`.
+			 *
+			 * This will load the engine if it is not loaded, and preload the main pck.
+			 *
+			 * This method expects the initial config (or the override) to have both the :js:attr:`executable` and :js:attr:`mainPack`
+			 * properties set (normally done by the editor during export).
+			 *
+			 * @param {EngineConfig} override An optional configuration override.
+			 * @return {Promise} Promise that resolves once the game started.
+			 */
+			startGame: function (override) {
+				this.config.update(override);
+				// Add main-pack argument.
+				const exe = this.config.executable;
+				const pack = this.config.mainPack || `${exe}.pck`;
+				this.config.args = ['--main-pack', pack].concat(this.config.args);
+				// Start and init with execName as loadPath if not inited.
+				const me = this;
+				return Promise.all([
+					this.init(exe),
+					this.preloadFile(pack, pack),
+				]).then(function () {
+					return me.start.apply(me);
+				});
+			},
+
+			/**
+			 * Create a file at the specified ``path`` with the passed as ``buffer`` in the instance's file system.
+			 *
+			 * @param {string} path The location where the file will be created.
+			 * @param {ArrayBuffer} buffer The content of the file.
+			 */
+			copyToFS: function (path, buffer) {
+				if (this.rtenv == null) {
+					throw new Error('Engine must be inited before copying files');
+				}
+				this.rtenv['copyToFS'](path, buffer);
+			},
+
+			/**
+			 * Request that the current instance quit.
+			 *
+			 * This is akin the user pressing the close button in the window manager, and will
+			 * have no effect if the engine has crashed, or is stuck in a loop.
+			 *
+			 */
+			requestQuit: function () {
+				if (this.rtenv) {
+					this.rtenv['request_quit']();
+				}
+			},
+
+			/**
+			 * Install the progressive-web app service worker.
+			 * @returns {Promise} The service worker registration promise.
+			 */
+			installServiceWorker: function () {
+				if (this.config.serviceWorker && 'serviceWorker' in navigator) {
+					try {
+						return navigator.serviceWorker.register(this.config.serviceWorker);
+					} catch (e) {
+						return Promise.reject(e);
+					}
+				}
+				return Promise.resolve();
+			},
+		};
+
+		Engine.prototype = proto;
+		// Closure compiler exported instance methods.
+		Engine.prototype['init'] = Engine.prototype.init;
+		Engine.prototype['preloadFile'] = Engine.prototype.preloadFile;
+		Engine.prototype['start'] = Engine.prototype.start;
+		Engine.prototype['startGame'] = Engine.prototype.startGame;
+		Engine.prototype['copyToFS'] = Engine.prototype.copyToFS;
+		Engine.prototype['requestQuit'] = Engine.prototype.requestQuit;
+		Engine.prototype['installServiceWorker'] = Engine.prototype.installServiceWorker;
+		// Also expose static methods as instance methods
+		Engine.prototype['load'] = Engine.load;
+		Engine.prototype['unload'] = Engine.unload;
+		return new Engine(initConfig);
+	}
+
+	// Closure compiler exported static methods.
+	SafeEngine['load'] = Engine.load;
+	SafeEngine['unload'] = Engine.unload;
+
+	// Feature-detection utilities.
+	SafeEngine['isWebGLAvailable'] = Features.isWebGLAvailable;
+	SafeEngine['isFetchAvailable'] = Features.isFetchAvailable;
+	SafeEngine['isSecureContext'] = Features.isSecureContext;
+	SafeEngine['isCrossOriginIsolated'] = Features.isCrossOriginIsolated;
+	SafeEngine['isSharedArrayBufferAvailable'] = Features.isSharedArrayBufferAvailable;
+	SafeEngine['isAudioWorkletAvailable'] = Features.isAudioWorkletAvailable;
+	SafeEngine['getMissingFeatures'] = Features.getMissingFeatures;
+
+	return SafeEngine;
+}());
+if (typeof window !== 'undefined') {
+	window['Engine'] = Engine;
+}

platform/web/js/engine/features.js

@@ -0,0 +1,106 @@
+const Features = {
+	/**
+	 * Check whether WebGL is available. Optionally, specify a particular version of WebGL to check for.
+	 *
+	 * @param {number=} [majorVersion=1] The major WebGL version to check for.
+	 * @returns {boolean} If the given major version of WebGL is available.
+	 * @function Engine.isWebGLAvailable
+	 */
+	isWebGLAvailable: function (majorVersion = 1) {
+		try {
+			return !!document.createElement('canvas').getContext(['webgl', 'webgl2'][majorVersion - 1]);
+		} catch (e) { /* Not available */ }
+		return false;
+	},
+
+	/**
+	 * Check whether the Fetch API available and supports streaming responses.
+	 *
+	 * @returns {boolean} If the Fetch API is available and supports streaming responses.
+	 * @function Engine.isFetchAvailable
+	 */
+	isFetchAvailable: function () {
+		return 'fetch' in window && 'Response' in window && 'body' in window.Response.prototype;
+	},
+
+	/**
+	 * Check whether the engine is running in a Secure Context.
+	 *
+	 * @returns {boolean} If the engine is running in a Secure Context.
+	 * @function Engine.isSecureContext
+	 */
+	isSecureContext: function () {
+		return window['isSecureContext'] === true;
+	},
+
+	/**
+	 * Check whether the engine is cross origin isolated.
+	 * This value is dependent on Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy headers sent by the server.
+	 *
+	 * @returns {boolean} If the engine is running in a Secure Context.
+	 * @function Engine.isSecureContext
+	 */
+	isCrossOriginIsolated: function () {
+		return window['crossOriginIsolated'] === true;
+	},
+
+	/**
+	 * Check whether SharedBufferArray is available.
+	 *
+	 * Most browsers require the page to be running in a secure context, and the
+	 * the server to provide specific CORS headers for SharedArrayBuffer to be available.
+	 *
+	 * @returns {boolean} If SharedArrayBuffer is available.
+	 * @function Engine.isSharedArrayBufferAvailable
+	 */
+	isSharedArrayBufferAvailable: function () {
+		return 'SharedArrayBuffer' in window;
+	},
+
+	/**
+	 * Check whether the AudioContext supports AudioWorkletNodes.
+	 *
+	 * @returns {boolean} If AudioWorkletNode is available.
+	 * @function Engine.isAudioWorkletAvailable
+	 */
+	isAudioWorkletAvailable: function () {
+		return 'AudioContext' in window && 'audioWorklet' in AudioContext.prototype;
+	},
+
+	/**
+	 * Return an array of missing required features (as string).
+	 *
+	 * @returns {Array<string>} A list of human-readable missing features.
+	 * @function Engine.getMissingFeatures
+	 * @param {{threads: (boolean|undefined)}} supportedFeatures
+	 */
+	getMissingFeatures: function (supportedFeatures = {}) {
+		const {
+			// Quotes are needed for the Closure compiler.
+			'threads': supportsThreads = true,
+		} = supportedFeatures;
+
+		const missing = [];
+		if (!Features.isWebGLAvailable(2)) {
+			missing.push('WebGL2 - Check web browser configuration and hardware support');
+		}
+		if (!Features.isFetchAvailable()) {
+			missing.push('Fetch - Check web browser version');
+		}
+		if (!Features.isSecureContext()) {
+			missing.push('Secure Context - Check web server configuration (use HTTPS)');
+		}
+
+		if (supportsThreads) {
+			if (!Features.isCrossOriginIsolated()) {
+				missing.push('Cross-Origin Isolation - Check that the web server configuration sends the correct headers.');
+			}
+			if (!Features.isSharedArrayBufferAvailable()) {
+				missing.push('SharedArrayBuffer - Check that the web server configuration sends the correct headers.');
+			}
+		}
+
+		// Audio is normally optional since we have a dummy fallback.
+		return missing;
+	},
+};

platform/web/js/engine/preloader.js

@@ -0,0 +1,133 @@
+const Preloader = /** @constructor */ function () { // eslint-disable-line no-unused-vars
+	function getTrackedResponse(response, load_status) {
+		function onloadprogress(reader, controller) {
+			return reader.read().then(function (result) {
+				if (load_status.done) {
+					return Promise.resolve();
+				}
+				if (result.value) {
+					controller.enqueue(result.value);
+					load_status.loaded += result.value.length;
+				}
+				if (!result.done) {
+					return onloadprogress(reader, controller);
+				}
+				load_status.done = true;
+				return Promise.resolve();
+			});
+		}
+		const reader = response.body.getReader();
+		return new Response(new ReadableStream({
+			start: function (controller) {
+				onloadprogress(reader, controller).then(function () {
+					controller.close();
+				});
+			},
+		}), { headers: response.headers });
+	}
+
+	function loadFetch(file, tracker, fileSize, raw) {
+		tracker[file] = {
+			total: fileSize || 0,
+			loaded: 0,
+			done: false,
+		};
+		return fetch(file).then(function (response) {
+			if (!response.ok) {
+				return Promise.reject(new Error(`Failed loading file '${file}'`));
+			}
+			const tr = getTrackedResponse(response, tracker[file]);
+			if (raw) {
+				return Promise.resolve(tr);
+			}
+			return tr.arrayBuffer();
+		});
+	}
+
+	function retry(func, attempts = 1) {
+		function onerror(err) {
+			if (attempts <= 1) {
+				return Promise.reject(err);
+			}
+			return new Promise(function (resolve, reject) {
+				setTimeout(function () {
+					retry(func, attempts - 1).then(resolve).catch(reject);
+				}, 1000);
+			});
+		}
+		return func().catch(onerror);
+	}
+
+	const DOWNLOAD_ATTEMPTS_MAX = 4;
+	const loadingFiles = {};
+	const lastProgress = { loaded: 0, total: 0 };
+	let progressFunc = null;
+
+	const animateProgress = function () {
+		let loaded = 0;
+		let total = 0;
+		let totalIsValid = true;
+		let progressIsFinal = true;
+
+		Object.keys(loadingFiles).forEach(function (file) {
+			const stat = loadingFiles[file];
+			if (!stat.done) {
+				progressIsFinal = false;
+			}
+			if (!totalIsValid || stat.total === 0) {
+				totalIsValid = false;
+				total = 0;
+			} else {
+				total += stat.total;
+			}
+			loaded += stat.loaded;
+		});
+		if (loaded !== lastProgress.loaded || total !== lastProgress.total) {
+			lastProgress.loaded = loaded;
+			lastProgress.total = total;
+			if (typeof progressFunc === 'function') {
+				progressFunc(loaded, total);
+			}
+		}
+		if (!progressIsFinal) {
+			requestAnimationFrame(animateProgress);
+		}
+	};
+
+	this.animateProgress = animateProgress;
+
+	this.setProgressFunc = function (callback) {
+		progressFunc = callback;
+	};
+
+	this.loadPromise = function (file, fileSize, raw = false) {
+		return retry(loadFetch.bind(null, file, loadingFiles, fileSize, raw), DOWNLOAD_ATTEMPTS_MAX);
+	};
+
+	this.preloadedFiles = [];
+	this.preload = function (pathOrBuffer, destPath, fileSize) {
+		let buffer = null;
+		if (typeof pathOrBuffer === 'string') {
+			const me = this;
+			return this.loadPromise(pathOrBuffer, fileSize).then(function (buf) {
+				me.preloadedFiles.push({
+					path: destPath || pathOrBuffer,
+					buffer: buf,
+				});
+				return Promise.resolve();
+			});
+		} else if (pathOrBuffer instanceof ArrayBuffer) {
+			buffer = new Uint8Array(pathOrBuffer);
+		} else if (ArrayBuffer.isView(pathOrBuffer)) {
+			buffer = new Uint8Array(pathOrBuffer.buffer);
+		}
+		if (buffer) {
+			this.preloadedFiles.push({
+				path: destPath,
+				buffer: pathOrBuffer,
+			});
+			return Promise.resolve();
+		}
+		return Promise.reject(new Error('Invalid object for preloading'));
+	};
+};