feat: Add context menu item to export scene and nodes

[yuripourre]

Title

Export scene as .babylon

Summary

Export the current scene as a .babylon file

Changes Made

Added export scene (.babylonjs)

• In the File menu added an option to export the scene

Benefits

• The current scene can be exported as .babylon (which can be easily used outside the editor).
• The .babylon can be reimported in the editor as a composite object/prefab (like in Unity 3d)

Screencast.From.2025-09-01.19-26-04.mp4

Closes #601

[julien-moreau]

In order to prepare prefabs, I suggest that a portion of the scene should be exporable via a right-click on a node in the graph. Instead of the entire scene
What do you think?

[yuripourre]

@julien-moreau that's a really good idea. I will modify this PR.

[julien-moreau]

For the full scene export, it can be in the right-click menu of the scene node

[yuripourre]

@julien-moreau Updated!

[julien-moreau]

I thinking about assets, I forgot last time.
What is the usage if the assets (textures assigned to materials for meshes for example) are not exported. The .babylon is kind of corrupted as it'll try to load assets not available near it.

[yuripourre]

I thinking about assets, I forgot last time. What is the usage if the assets (textures assigned to materials for meshes for example) are not exported. The .babylon is kind of corrupted as it'll try to load assets not available near it.

That's true!
In that case, do you think the best way would be to export the texture in the .babylon file so the model can be loaded without issues? Even though it will not be available as asset when reloaded?

Or do you think when importing a .babylon file we could strip the assets from the file and import as separate assets?

We can also let the .babylon "prefab" break and let the user assign a different material.

[julien-moreau]

I just fixed an issue in the editor when importing meshes: the process that extracts textures in case they were embeded.
I think packing everything in the .babylon may work: the .babylon file works as standalone, allows to quickly drag'n'drop it in the sandbox or load it in any project not done with the editor. In case it's added later in the editor it'll be able to extract the textures so that's perfect.

I was think about prefabs and it'll require some huge work finally. I think this PR can be the "export as babylon" feature. It does only that. In the future we'll create kind of a "create prefab" menu that will manage way more things (such as prefab Ids to retrieve resources if they already exist etc.).

[yuripourre]

@julien-moreau that's great, then I will rebase and fix the comments somewhere this weekend.

For me that would be more than enough to use as prefabs while we don't have the proper feature.

Thanks for reviewing and the suggestions

[julien-moreau]

For me that would be more than enough to use as prefabs while we don't have the proper feature.

I totally agree! We'll just not call it prefab for instance ^^

[yuripourre]

@julien-moreau
I will try to test more later today but added particle systems and sound export

[julien-moreau]

I take it for the next release (as I'm releasing today some fixes). I'll probably merge it and rework it if needed. Thanks for the good base you provided!

[yuripourre]

@julien-moreau whoa! Thank you so much for reviewing.
This feature is one of those that will make my life much easier.

[julien-moreau]

I'm sorry, I took sprites support instead which took me more time than I have anticipated
I'll focus on this one after ^^

[b3nten]

This would be huge for composing scenes or parts of scenes and then loading them into a Babylon app that's written "manually" outside the editor. Hope it lands soon!

[julien-moreau]

This would be huge for composing scenes or parts of scenes and then loading them into a Babylon app that's written "manually" outside the editor. Hope it lands soon!

Totally agree! I'm reviewing it ASAP
@yuripourre do you think this PR is ready for review?

[yuripourre]

@julien-moreau, yes, please go ahead :)

Feel free to change if something can be better.