public void setCurrentSceneIndex(int index) {
        mSelectedSceneIndex = index;
        if (index < 0 || index >= mSceneArray.size()){
            // Scene object may not yet have been initialized, so return here.
            return;
        }

        setViroContext();
        mViroView.setScene(mSceneArray.get(mSelectedSceneIndex).getNativeScene());
        mSceneArray.get(mSelectedSceneIndex).parentDidAppear();
    }
We may need to reload the materials if the renderer was destroyed, but the app was not
and the user resumed.
android/viro_bridge/src/main/java/com/viromedia/bridge/component/VRT3DSceneNavigator.java