You can stream it. Here’s an example using Unity: https://appmana.com/watch/virtualtestdrive

For runtime loading in such an architecture, you can using an asset like TriLib.

There are many streaming ideas. Most were poorly executed. I wouldn’t generalize based on those. It is definitely the future of delivery for many reasons besides technology.

Yes. I'd love to load and re-use existing js libs as well as add code to a project and rules at runtime. I'd have loved to see WebXR being an extension of HTML instead of it being an extension to the canvas.

Not sure what you're asking, exactly?

Unity (and I presume Unreal) can do the same procedural generation stuff today your can do in js. There's many libraries/tutorials etc

Basically i'd like to add, edit, store and load code during runtime.

Oh, code? I assumed you meant geometry and/or materials.

Yes, it's possible. I can think of several ways to approach it. Not quite as cleanly as with javaScript, mind.

Heh. What would be your favourite thoughts/combo here?

Sorry for not being clear on the code part. I assumed USD and the like would be the norm now. "Complex objects" is not really helpful in this context, though.

USD is fairly widely used. But it's not "code" in the sense that I mean it. It's (mostly) declarative (like HTML) so I lump it in with obj, fbx and gltf.

I am assuming code means "executable code" - I know the boundaries are fuzzy here and some file formats are Turing complete - but I guess what I'm saying is that I'm still not sure what you're asking!

Code that I can create during runtime. Ideally interactively.

Just a heads up, when folks say “complex 3d objects”, it’s usually assumed that they’re talking about things like GLTF files, which contain geometry, materials, lighting elements, animations, etc, and which Unity/Unreal can absolutely load/unload at runtime or even stream from a media server online (so they don’t have to be in the binary).

However, once you cross over into scripting code, you are in fact crossing a barrier, and it does become harder to hot-reload the way you can in a JS app. Like, the fact that Unity scripts are written in C# and have to be compiled and linked is a pretty huge impediment that you don’t face when loading almost any other kind of asset.

I’m right there with you: Hot-reloading and 3D is a thrilling combination, and tools like react-three-fiber are miles ahead of anything I’ve seen in Unity-land in terms of laying foundations for stuff like this. I’d recommend emphasizing “hot-reloading code” when drawing this distinction with Unity/Unreal folks to better get across the magnitude of what you’re looking for.

Thanks for both hints.

I recently had more contact with gaming engines than I originally wanted and there's always this kind of community-specific vocabulary whenever you cross borders. Oh no,like in real life.

I wrote up a post on my R3F based WebXR hot reloading setup here:

https://github.com/gregfagan/blog/blob/main/xr-remote-displa...

You don’t actually need this if you’re just working on graphics, as usually a flat projection is fine, but it is quite nice to work inside your own XR app while iterating on the interaction.

Nice. I also started looking into possible WebRTC sources and servers since at least this could be integrated quite well into WebXR.

Unfortunately I find myself cycling thru needed components for interactivity these day and being stuck between competing SW and HW constraints.

Will give it a closer read next week.

IMO, the main impedance towards scripted graphics facilitating hot reloading is that they are generally coded in object hierarchies whose nested is difficult to serialise. I have found using the 2d canvas context as an immediate mode renderer alongside a single global store allows me to create workflows more similar to what one would expect with React.

Is hot-reloading code useful past the development stage? In what way? (I'm not familiar with 3D development at all).

For me it's about allowing more than plain UI interaction and about interactively building immersive working enviroments and tool-spaces.

Ah, that's an interesting option, thanks!

CSS supports many 3D transforms, I wonder if VR browsers implement that in any sort of 3D plane.

Cool.

If I could xr-dive into a css-3d-transformed world of objects instead of having them projected onto the 2d window right away, that would be what I was looking for in the second part of the comment above. Not sure if WebXR perspective and a 3d space is provided right now at the same level these css transforms are used.

you can calculate 2D CSS transforms which match the equivalent transforms of your WebGL scene in WebXR - as an efficient but hacky way to (for instance) do live video overlays in 3D without having to mess around importing the video texture into WebGL (assuming you don’t need occlusion or environmental effects etc).

we’re toying with this as an approach for video overlays in https://thirdroom.io, especially for underpowered devices.

Yes, I've seen similar examples. Reminded me of HW video card overlays and I hoped we would have a better solution soon.

But currently probably it what's there. Would this work as well for other HTML content, like dynamically projecting a whole DIV into/over a canvas scene that I would then be able to have positioned over some surface in VR?

Love the product/concept, btw.

I don't think people realize how dog shit slow the DOM is. There is a reason webXR uses the canvas.

For Unity, I think you can just dynamically load DLLs as long as you're not on a plane form that requires AOT (iOS). Even then, for both Unreal and Unity there are many options to use scripting languages like js or lua or what have you.

Ok. will look into scripting plugins then for now, probably bridging some introspected interfaces. Would be nice if one could add/integrate existing JS libs but that's outside the Unity context.

I'm keeping a close eye on WASM as a way to hotload code in Unity and as a way to access libraries from a variety of ecosystems.

Good point.

So many great exec environments already for WASM. Is there already something available for Unity? Maybe even with a source language and compiler built in?

My focus currently is on creating code inside a running app (by the user) with references to selected Unity objects and their methods. While WebXR is great for this, the first (and sometimes only) SDK implementations for certain devices are usually in Unity.

WASM probably ist great for hotloading but would need a more complex toolset available at runtime to edit and create. Interactivity and incremental code creation would also be better in a scripting envirnment.

I went with Lua personally. I have mixed feelings about some aspects of the language but the ease of integration was hard to fault.

I'm using Moonsharp which is interpreted rather than jitted but Blua looks promising if performance on the Lua side is critical.

Will have a look at Moonsharp. Thanks.

I got around lua so far, but bindigs seemed easy and a friend just chose it over integrating python just recently, so it seems to be getting some traction again, especially in tools and such to get a first step beyond a purely graphical UI.

Unity support for WebXR has been at the back of thier roadmap Under Consideration [1] for years and the valiant community driven efforts (@DePanther) are just too hard to keep current so lot of key Unity release improvements are missing.

[1] https://unity.com/roadmap/unity-platform/arvr