Viewer - better extendibility:

onTemplateLoaded, initEngine and initScene can now be extended without making sure that important parts of the code will not run (like the observables)

Viewer/src/viewer/viewer.ts

@@ -19,8 +19,9 @@ export abstract class AbstractViewer {
     public onSceneInitObservable: PromiseObservable<Scene>;
     public onEngineInitObservable: PromiseObservable<Engine>;
     public onModelLoadedObservable: PromiseObservable<AbstractMesh[]>;
+    public onInitDoneObservable: PromiseObservable<AbstractViewer>;
 
-    private canvas: HTMLCanvasElement;
+    protected canvas: HTMLCanvasElement;
 
     constructor(public containerElement: HTMLElement, initialConfiguration: ViewerConfiguration = {}) {
         // if exists, use the container id. otherwise, generate a random string.
@@ -33,6 +34,7 @@ export abstract class AbstractViewer {
         this.onSceneInitObservable = new PromiseObservable();
         this.onEngineInitObservable = new PromiseObservable();
         this.onModelLoadedObservable = new PromiseObservable();
+        this.onInitDoneObservable = new PromiseObservable();
 
         // add this viewer to the viewer manager
         viewerManager.addViewer(this);
@@ -68,7 +70,7 @@ export abstract class AbstractViewer {
                 if (canvas) {
                     this.canvas = canvas;
                 }
-                this.onTemplatesLoaded();
+                this._onTemplateLoaded();
             });
         });
 
@@ -114,16 +116,33 @@ export abstract class AbstractViewer {
      * @memberof AbstractViewer
      */
     protected onTemplatesLoaded(): Promise<AbstractViewer> {
-        let autoLoadModel = !!this.configuration.model;
-        return this.initEngine().then(() => {
-            if (autoLoadModel) {
-                return this.loadModel();
-            } else {
-                return this.scene || this.initScene();
-            }
-        }).then(() => {
-            return this;
-        });
+        return Promise.resolve(this);
+    }
+
+    /**
+     * This will force the creation of an engine and a scene.
+     * It will also load a model if preconfigured.
+     * But first - it will load the extendible onTemplateLoaded()!
+     */
+    private _onTemplateLoaded(): Promise<AbstractViewer> {
+        return this.onTemplatesLoaded().then(() => {
+            let autoLoadModel = !!this.configuration.model;
+            return this.initEngine().then(() => {
+                return this.onEngineInitObservable.notifyWithPromise(this);
+            }).then(() => {
+                if (autoLoadModel) {
+                    return this.loadModel();
+                } else {
+                    return this.scene || this.initScene();
+                }
+            }).then(() => {
+                return this.onSceneInitObservable.notifyWithPromise(this);
+            }).then(() => {
+                return this.onInitDoneObservable.notifyWithPromise(this);
+            }).then(() => {
+                return this;
+            });
+        })
     }
 
     /**
@@ -157,9 +176,7 @@ export abstract class AbstractViewer {
             this.engine.setHardwareScalingLevel(scale);
         }
 
-        return this.onEngineInitObservable.notifyWithPromise(this.engine).then(() => {
-            return this.engine;
-        });
+        return Promise.resolve(this.engine);
     }
 
     protected initScene(): Promise<Scene> {
@@ -176,9 +193,7 @@ export abstract class AbstractViewer {
         if (this.configuration.scene && this.configuration.scene.debug) {
             this.scene.debugLayer.show();
         }
-        return this.onSceneInitObservable.notifyWithPromise(this.scene).then(() => {
-            return this.scene!;
-        });
+        return Promise.resolve(this.scene);
     }
 
     public loadModel(model: any = this.configuration.model, clearScene: boolean = true): Promise<Scene> {