use getScene like rtt

src/Materials/Textures/renderTargetTexture.ts

@@ -1013,7 +1013,7 @@ export class MultiviewRenderTarget extends RenderTargetTexture {
      * @param scene scene used with the render target
      * @param size the size of the render target (used for each view)
      */
-    constructor(private scene: Scene, size: number | { width: number, height: number } | { ratio: number } = 512) {
+    constructor(scene: Scene, size: number | { width: number, height: number } | { ratio: number } = 512) {
         super("multiview rtt", size, scene, false, true, InternalTexture.DATASOURCE_UNKNOWN, false, undefined, false, false, true, undefined, true);
         var internalTexture = scene.getEngine().createMultiviewRenderTargetTexture(this.getRenderWidth(), this.getRenderHeight());
         internalTexture.isMultiview = true;
@@ -1028,7 +1028,7 @@ export class MultiviewRenderTarget extends RenderTargetTexture {
         if (!this._texture) {
             return;
         }
-        this.scene.getEngine().bindMultiviewFramebuffer(this._texture);
+        this.getScene()!.getEngine().bindMultiviewFramebuffer(this._texture);
     }
 
     /**