Two scenes created in simple example.

[mission-minnow]

Here's the code sandbox: https://codesandbox.io/s/quiet-haze-xyodgq?file=/src/App.tsx

In this simple example, I'm just creating a scene with a non-default clear color. If I log when the scene gets mounted, I get two different scenes.

Check the console output.

onSceneMount={(args)=>console.log(args)}

{scene: Scene, canvas: HTMLCanvasElement} {scene: Scene, canvas: HTMLCanvasElement}

[AJamesPhillips]

Looks like it's reusing the canvas but creating a second scene: https://codesandbox.io/s/morning-star-etwzsr?file=/src/App.tsx

However I run the following code locally and it does not seem to call the onSceneMount twice. I am running react-babylonjs @ 3.1.3.

[brianzinn]

I think it's because you are in Strict mode -- and thank-you for the helpful sandbox to reproduce.

Yes, confirmed with this snippet:

// in index.tsx
root.render(
    <App />
);

[mz8i]

Somewhat related I think - I just encountered a problem after upgrading to React 18 (which in strict mode runs each effect twice to check for proper clean-up). My problem is with enabling physics. When strict mode is enabled, I get an error from the AmmoJS plugin (this.world is null) . Removing strict mode removes the problem, but it suggests that there should be some fixes to the main useEffect in Scene.tsx?

[brianzinn]

I gotta look more into this… The irony is that it was changed not long ago to use hooks!!

[brianzinn]

I have done some React 18.0-18.2 compatibility changes this week. It's working in StrictMode on the sandboxes I have tried. If you can share a reproduction then I will be happy to look at solutions. AmmoJS should allow re-creating scenes - so perhaps something in your code has made assumptions otherwise?

[brianzinn]

closing from inactivity. looks resolved and due to strict mode. thanks for your contribution.