Merge pull request #55 from demike/feat/before-render-callbacks-for-v…

…iews

feat: emit before renderer pass

projects/ngx-three/src/lib/ThEngine.service.ts

@@ -137,6 +137,9 @@ export class ThEngineService implements OnDestroy {
         continue;
       }
       this.applyRendererParametersFromView(view, renderer);
+      if (isObserved(view.onCurrentRendererPass)) {
+        this.ngZone.run(() => view.onCurrentRendererPass.emit({ renderer, scene, camera, engine: this }));
+      }
       if (view.effectComposer) {
         view.effectComposer.render();
         return;

projects/ngx-three/src/lib/ThView.ts

@@ -46,6 +46,22 @@ export class ThView implements OnInit {
   @Input()
   public scene?: ThScene;
 
+  /**
+   * Emits before the render loop starts for this view (before effectComposer or main render pass, but after setting up the viewPort on the renderer).
+   * It emits for every renderer.
+   * It can be used to modify the scene, camera or renderer before rendering
+   * and to do additional render passes
+   *
+   * @Note onRender is called before this event (and only once for all renderers)
+   */
+  @Output()
+  onCurrentRendererPass = new EventEmitter<{
+    renderer: Renderer;
+    scene: ThScene;
+    camera: ThCamera;
+    engine: ThEngineService;
+  }>();
+
   @ContentChild(ThScene)
   public set contentScene(scene: ThScene | undefined) {
     if (scene) {