Support EXT_meshopt_compression

packages/model-viewer/src/features/loading.ts

@@ -90,12 +90,14 @@ export declare interface LoadingInterface {
 export declare interface LoadingStaticInterface {
   dracoDecoderLocation: string;
   ktx2TranscoderLocation: string;
+  meshoptDecoderLocation: string;
   mapURLs(callback: (url: string) => string): void;
 }
 
 export interface ModelViewerGlobalConfig {
   dracoDecoderLocation?: string;
   ktx2TranscoderLocation?: string;
+  meshoptDecoderLocation?: string;
   powerPreference?: string;
 }
 
@@ -114,8 +116,8 @@ export interface ModelViewerGlobalConfig {
  *
  * ```html
  * <script>
- * ModelViewerElement = self.ModelViewerElement || {};
- * ModelViewerElement.dracoDecoderLocation =
+ * self.ModelViewerElement = self.ModelViewerElement || {};
+ * self.ModelViewerElement.dracoDecoderLocation =
  *     'http://example.com/location/of/draco/decoder/files/';
  * </script>
  * ```
@@ -168,6 +170,14 @@ export const LoadingMixin = <T extends Constructor<ModelViewerElementBase>>(
       return CachingGLTFLoader.getKTX2TranscoderLocation();
     }
 
+    static set meshoptDecoderLocation(value: string) {
+      CachingGLTFLoader.setMeshoptDecoderLocation(value);
+    }
+
+    static get meshoptDecoderLocation() {
+      return CachingGLTFLoader.getMeshoptDecoderLocation();
+    }
+
     /**
      * If provided, the callback will be passed each resource URL before a
      * request is sent. The callback may return the original URL, or a new URL
@@ -319,6 +329,10 @@ export const LoadingMixin = <T extends Constructor<ModelViewerElementBase>>(
           ModelViewerElement.ktx2TranscoderLocation ||
           DEFAULT_KTX2_TRANSCODER_LOCATION;
       CachingGLTFLoader.setKTX2TranscoderLocation(ktx2TranscoderLocation);
+
+      if (ModelViewerElement.meshoptDecoderLocation) {
+        CachingGLTFLoader.setMeshoptDecoderLocation(ModelViewerElement.meshoptDecoderLocation);
+      }
     }
 
     connectedCallback() {

packages/model-viewer/src/three-components/CachingGLTFLoader.ts

@@ -49,6 +49,18 @@ export const loadWithLoader =
       });
     };
 
+/** Helper to load a script tag. */
+const fetchScript = (src: string): Promise<Event> => {
+  return new Promise((resolve, reject) => {
+      const script = document.createElement('script');
+      document.body.appendChild(script);
+      script.onload = resolve;
+      script.onerror = reject;
+      script.async = true;
+      script.src = src;
+  });
+};
+
 const cache = new Map<string, Promise<GLTFInstance>>();
 const preloaded = new Map<string, boolean>();
 
@@ -58,6 +70,18 @@ const dracoLoader = new DRACOLoader();
 let ktx2TranscoderLocation: string;
 const ktx2Loader = new KTX2Loader();
 
+let meshoptDecoderLocation: string;
+let meshoptDecoder: Promise<typeof MeshoptDecoder> | undefined;
+
+interface MeshoptDecoder {
+  ready: Promise<void>;
+  supported: boolean;
+}
+
+declare global {
+  const MeshoptDecoder: MeshoptDecoder;
+}
+
 export const $loader = Symbol('loader');
 export const $evictionPolicy = Symbol('evictionPolicy');
 const $GLTFInstance = Symbol('GLTFInstance');
@@ -83,6 +107,19 @@ export class CachingGLTFLoader<T extends GLTFInstanceConstructor =
     return ktx2TranscoderLocation;
   }
 
+  static setMeshoptDecoderLocation(url: string) {
+    if (meshoptDecoderLocation !== url) {
+      meshoptDecoderLocation = url;
+      meshoptDecoder = fetchScript(url)
+        .then(() => MeshoptDecoder.ready)
+        .then(() => MeshoptDecoder);
+    }
+  }
+
+  static getMeshoptDecoderLocation() {
+    return meshoptDecoderLocation;
+  }
+
   static initializeKTX2Loader(renderer: WebGLRenderer) {
     ktx2Loader.detectSupport(renderer);
   }
@@ -155,6 +192,10 @@ export class CachingGLTFLoader<T extends GLTFInstanceConstructor =
     this.dispatchEvent(
         {type: 'preload', element: element, src: url} as PreloadEvent);
     if (!cache.has(url)) {
+      if (meshoptDecoder != null) {
+        this[$loader].setMeshoptDecoder(await meshoptDecoder);
+      }
+
       const rawGLTFLoads =
           loadWithLoader(url, this[$loader], (progress: number) => {
             progressCallback(progress * 0.8);

packages/modelviewer.dev/data/docs.json

@@ -112,7 +112,15 @@
         "htmlName": "ktx2TranscoderLocation",
         "description": "This static, writable property sets <span class='attribute'>&lt;model-viewer&gt;</span>'s KTX2 transcoder location URL. By default, the KTX2 transcoder will be loaded from a Google CDN.",
         "links": [
-          "<a href=\"../examples/loading/#dracoSupport\"><span class='attribute'>dracoDecoderLocation</span> example</a>"
+          "<a href=\"../examples/loading/#ktx2Support\"><span class='attribute'>ktx2TranscoderLocation</span> example</a>"
+        ]
+      },
+      {
+        "name": "meshoptDecoderLocation",
+        "htmlName": "meshoptDecoderLocation",
+        "description": "This static, writable property sets <span class='attribute'>&lt;model-viewer&gt;</span>'s Meshopt decoder location URL. By default, the Meshopt decoder is not enabled.",
+        "links": [
+          "<a href=\"../examples/loading/#meshoptSupport\"><span class='attribute'>meshoptDecoderLocation</span> example</a>"
         ]
       },
       {

packages/modelviewer.dev/data/examples.json

@@ -39,6 +39,10 @@
         "htmlId": "ktx2Support",
         "name": "KTX2 Support"
       },
+      {
+        "htmlId": "meshoptSupport",
+        "name": "Meshopt Support"
+      },
       {
         "htmlId": "usdzModel",
         "name": "USDZ Model"

packages/modelviewer.dev/examples/loading/index.html

@@ -41,7 +41,7 @@
 
 <body>
 
-<div class="examples-page">  
+<div class="examples-page">
   <div class="sidebar" id="sidenav"></div>
   <div id="toggle"></div>
 
@@ -57,7 +57,7 @@ <h2 class="demo-title">Display a poster until loaded</h2>
             <h4></h4>
           </div>
           <example-snippet stamp-to="displayPoster" highlight-as="html">
-            
+
             <template>
 <style>
   model-viewer#reveal {
@@ -208,7 +208,7 @@ <h4></h4>
         </div>
       </div>
     </div>
-  
+
     <div class="sample">
       <div id="glbModel" class="demo"></div>
       <div class="content">
@@ -227,7 +227,7 @@ <h4></h4>
         </div>
       </div>
     </div>
-  
+
     <div class="sample">
       <div id="dracoSupport" class="demo"></div>
       <div class="content">
@@ -241,7 +241,7 @@ <h4>
             <h4>
               In order to load such models, an auxilliary decoder is
               required and will be loaded on-demand from a Google CDN when
-              a DRACO-compressed model is detected. See below to learn 
+              a DRACO-compressed model is detected. See below to learn
               how to customize this behavior.
             </h4>
           </div>
@@ -264,8 +264,8 @@ <h4>
             <example-snippet inert-script highlight-as="html">
               <template>
 <script>
-ModelViewerElement = self.ModelViewerElement || {};
-ModelViewerElement.dracoDecoderLocation = 'http://example.com/location/of/draco/decoder/files/';
+self.ModelViewerElement = self.ModelViewerElement || {};
+self.ModelViewerElement.dracoDecoderLocation = 'http://example.com/location/of/draco/decoder/files/';
 </script>
             </template>
           </example-snippet>
@@ -330,7 +330,50 @@ <h4>
         </div>
       </div>
     </div>
-
+
+    <div class="sample">
+      <div id="meshoptSupport" class="demo"></div>
+      <div class="content">
+        <div class="wrapper">
+          <div class="heading">
+            <h2 class="demo-title">Meshopt support</h2>
+            <h4>
+              &lt;model-viewer&gt; supports loading glTF models that
+
+              use <a href="https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Vendor/EXT_meshopt_compression/README.md" target="_blank" rel="noopener">the Meshopt compression extension</a>.
+            </h4>
+            <h4>
+              In order to load such models, an auxiliary decoder is
+              required, and is not enabled by default.
+            </h4>
+          </div>
+          <example-snippet stamp-to="meshoptSupport" highlight-as="html">
+            <template>
+<model-viewer camera-controls alt="A 3D model of a mechanical coffee mug contraption" src="../../shared-assets/models/coffeemat.glb">
+</model-viewer>
+            </template>
+          </example-snippet>
+          <p>
+            Enable support for Meshopt compression by providing
+            <code>meshoptDecoderLocation</code>:
+          </p>
+          <example-snippet inert-script highlight-as="html">
+            <template>
+<script>
+self.ModelViewerElement = self.ModelViewerElement || {};
+self.ModelViewerElement.meshoptDecoderLocation = 'https://unpkg.com/meshoptimizer@0.16.0/meshopt_decoder.js';
+</script>
+            </template>
+          </example-snippet>
+          <p>
+            When customizing the decoder location, you must make sure that
+            the configuration is set <strong>before</strong> the first &lt;model-viewer&gt;
+            element is created on the page.
+          </p>
+        </div>
+      </div>
+    </div>
+
     <div class="sample">
       <div id="usdzModel" class="demo"></div>
       <div class="content">
@@ -348,7 +391,7 @@ <h4>Note that this won't display a model (as that requires a glTF or GLB), but c
         </div>
       </div>
     </div>
-  
+
     <div class="sample">
       <div id="noModel" class="demo"></div>
       <div class="content">
@@ -366,7 +409,7 @@ <h4>There's nothing to show, but also no error.</h4>
         </div>
       </div>
     </div>
-  
+
     <div class="sample">
       <div id="cyclingModels" class="demo"></div>
       <div class="content">
@@ -406,12 +449,17 @@ <h4></h4>
           <a href="https://poly.google.com/view/6uTsH2jqgVn">Shish kebab</a> by <a href="https://poly.google.com/user/4aEd8rQgKu2">Poly</a>,
           licensed under <a href="https://creativecommons.org/licenses/by/2.0/">CC-BY</a>.
         </li>
+
+        <li class="attribution">
+          <a href="https://sketchfab.com/3d-models/coffeemat-7fb196a40a6e4697aad9ca2f75c8b33d">Coffeemat</a> by <a href="https://sketchfab.com/OFFcours1">Roman Red</a>,
+          licensed under <a href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution</a>.
+        </li>
       </ul>
 
       <div style="margin-top:24px;" class="copyright">©Copyright 2018-2020 Google Inc. Licensed under the Apache License 2.0.</div>
       <div id='footer-links'></div>
   </div>
-      
+
 </div>
 
 </div>
@@ -427,6 +475,12 @@ <h4></h4>
   <script type="module" src="../built/dependencies.js">
   </script>
 
+  <!-- Enables Meshopt decoder. -->
+  <script>
+    self.ModelViewerElement = self.ModelViewerElement || {};
+    self.ModelViewerElement.meshoptDecoderLocation = 'https://unpkg.com/meshoptimizer@0.16.0/meshopt_decoder.js';
+  </script>
+
   <!-- Loads <model-viewer> on modern browsers: -->
   <script type="module" src="../../node_modules/@google/model-viewer/dist/model-viewer.js">
   </script>