122 lines
5.2 KiB
JavaScript
122 lines
5.2 KiB
JavaScript
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* WHY DOES THIS FILE EXIST?
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* -------------------------
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*
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* For each generated wasm file, emscripten generates a corollary JS file that is used to load the
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* wasm and set up its imports / exports. This file is a hand-authored addendum to the JS file that
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* emscripten generates, and we use it to store JavaScript-side utilities such as the asset
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* downloader and BufferDescriptor wrapper.
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*
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* Note that we should avoid certain modern JavaScript features in this file (e.g., for-of loops)
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* because emscripten uses a fairly rusty minifier.
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*/
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// Keep a counter of remaining asynchronous tasks (e.g., downloading assets) that must occur before
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// allowing the app to initialize. As soon as the counter hits zero, we know it is time to call the
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// app's onready callback. There is always at least 1 initialization task for loading the WASM
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// module.
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Filament.remainingInitializationTasks = 1;
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/// init ::function:: Downloads assets, loads the Filament module, and invokes a callback when done.
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///
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/// All JavaScript clients must call the init function, passing in a list of asset URL's and a
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/// callback. This callback gets invoked only after all assets have been downloaded and the Filament
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/// WebAssembly module has been loaded. Clients should only pass asset URL's that absolutely must
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/// be ready at initialization time.
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///
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/// When the callback is called, each downloaded asset is available in the `Filament.assets` global
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/// object, which contains a mapping from URL's to Uint8Array objects and DOM images.
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///
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/// assets ::argument:: Array of strings containing URL's of required assets.
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/// onready ::argument:: callback that gets invoked after all assets have been downloaded and the \
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/// Filament WebAssembly module has been loaded.
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Filament.init = function(assets, onready) {
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Filament.onReady = onready;
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Filament.remainingInitializationTasks += assets.length;
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Filament.assets = {};
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// Usage of glmatrix is optional. If it exists, then go ahead and augment it with some
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// useful math functions.
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if (typeof glMatrix !== 'undefined') {
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Filament.loadMathExtensions();
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}
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// Issue a fetch for each asset. After the last asset is downloaded, trigger the callback.
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Filament.fetch(assets, null, function(name) {
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if (--Filament.remainingInitializationTasks == 0 && Filament.onReady) {
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Filament.onReady();
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}
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});
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};
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// The postRun method is called by emscripten after it finishes compiling and instancing the
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// WebAssembly module. The JS classes that correspond to core Filament classes (e.g., Engine)
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// are not guaranteed to exist until this function is called.
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Filament.postRun = function() {
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Filament.loadClassExtensions();
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if (--Filament.remainingInitializationTasks == 0 && Filament.onReady) {
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Filament.onReady();
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}
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};
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/// fetch ::function:: Downloads assets and invokes a callback when done.
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///
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/// This utility consumes an array of URI strings and invokes callbacks after each asset is
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/// downloaded. Additionally, each downloaded asset becomes available in the `Filament.assets`
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/// global object, which is a mapping from URI strings to `Uint8Array`. If desired, clients can
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/// pre-populate entries in `Filament.assets` to circumvent HTTP requests (this should be done after
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/// calling `Filament.init`).
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///
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/// This function is used internally by `Filament.init` and `gltfio$FilamentAsset.loadResources`.
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///
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/// assets ::argument:: Array of strings containing URL's of required assets.
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/// onDone ::argument:: callback that gets invoked after all assets have been downloaded.
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/// onFetch ::argument:: optional callback that's invoked after each asset is downloaded.
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Filament.fetch = function(assets, onDone, onFetched) {
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var remainingAssets = assets.length;
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assets.forEach(function(name) {
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// Check if a buffer already exists in case the client wishes
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// to provide its own data rather than using a HTTP request.
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if (Filament.assets[name]) {
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if (onFetched) {
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onFetched(name);
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}
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if (--remainingAssets === 0 && onDone) {
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onDone();
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}
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} else {
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fetch(name).then(function(response) {
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if (!response.ok) {
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throw new Error(name);
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}
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return response.arrayBuffer();
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}).then(function(arrayBuffer) {
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Filament.assets[name] = new Uint8Array(arrayBuffer);
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if (onFetched) {
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onFetched(name);
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}
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if (--remainingAssets === 0 && onDone) {
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onDone();
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}
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});
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}
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});
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};
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