[WinUI3] Viewport3DX crash to a white background after nagivating to another page

[noudavinci]

Hi, I'm having a trouble with my WinUI 3 application: I have a <hx:Viewport3DX> inside one of my pages. At the first time navigating to that page, things work well. But after I switch to another page, then switch back, the viewport becomes white, and I can't react to the viewport anymore until I restart the program.
Before switching to another page:

After switching to another page:

the code I used to display the viewport:

<hx:Viewport3DX x:Name="ViveTracker_Viewport"
                Grid.Column="0" Grid.Row="0"
                Margin="0,0,11,0"
                Camera="{x:Bind MainVM.Camera}"
                EffectsManager="{x:Bind MainVM.EffectsManager}"
                BackgroundColor="#1d1d1d"
                EnableDeferredRendering="True"
                FXAALevel="Medium"
                EnableDpiScale="True">
    <hx:DirectionalLight3D Direction="{x:Bind MainVM.Camera.LookDirection}" Color="White" />
    <hx:Element3DPresenter x:Name="Preview_RootElements" Content="{x:Bind MainVM._root}" />
</hx:Viewport3DX>

That page has been cached using NavigationCacheMode="Required". All the content of the Viewport is delivered from an instance of class TrackingSpaceViewport containing camera, effectsmanager,...
I tried to turn off page caching with NavigationCacheMode="Disabled" but everytime I reopen that page, the memory keeps increasing and I think there is a memory leak in Viewport3DX (tested by commenting the viewport3dx code and it's gone).
Can anyone suggest me how to fix this?

[holance]

Check whether an new effect manager being created every time page is switched.

[noudavinci]

Thanks for your answer, but no Effect Manager being created. The Effect Manager is created once the instance of TrackingSpaceViewport is created, when the program starts. That instance lives with the program until the user closes them. I suspect that the render engine of the Viewport3DX will be terminated when the page switched, but does not being started when I switch back to the viewport page, don't know whether it's true or not. I tried searching online for the concept of interacting between WinUI and the HelixToolkit in terms of UI rendering, couldn't find anything in detail.
Temporarily, I put the Viewport3DX in another indenpendent window, so it will not be useless after switching to another page. But I really want to put it inside the navigation page.

[holance]

Could you create a sample project for me to debug?

[isenbergd]

Hi, I ran into the same issue. I was able to "solve" it by listening to the SizeChanged Event of the control and setting the width of the viewport to a fixed value and immediately back to "double.NaN".
This somehow forces a correct refresh.

InitializeComponent();
SizeChanged += (sender, args) =>
{
    PositioningViewport.Width = 800;
    DispatcherQueue.TryEnqueue(() => PositioningViewport.Width = double.NaN);
};

In your case PositioningViewport is ViveTracker_Viewport