Export 3D models or scenes

[sunjay]

Thanks for such an excellent library!

Since three provides a way to load gltf files (among other formats), could it also be possible to save/export objects/scenes to those formats as well? I want to use three to make a program that can load models, make specific types of edits, and then save the entire scene as a gltf file.

[kvark]

So you want to basically write a scene editor in with three? That sounds like an interesting project!

Writing the GLTF export would be quite a heavy undertaking, so it requires a dedicated volunteer ;)

[sunjay]

Since we already import GLTF, is there a way to "reverse" that code and get GLTF out. I don't know all the details of how this works, so I thought I would ask. :)

[kvark]

Well, neither do I :) Summining @alteous and @randomPoison in case they are interested to answer.

[randomPoison]

As far as I know it should be possible, though it may require some functionality be added to three-rs. three-rs already has functionality for walking the contents of the scene, which means you can construct the graph of nodes for the glTF document. I imagine the harder part would be to get the mesh and texture data from three-rs so that you can export it again, but it should be possible to add that functionality (assuming it hasn't already been added since I last worked on this project).

That said, I think @kvark is right to note that the glTF exporter is the harder part here. A cursory glance at crates.io doesn't turn up any crates for writing glTF files (only reading them). If someone could put together a crate for constructing glTF data in memory and writing it out, that would be a big first step towards being able to generate a glTF file from a three-rs scene!

[alteous]

This is a sensible suggestion and it should not be difficult to implement; however, it would require a fair amount of work. You could leverage the gltf-json crate to build the metadata. Writing the buffer and image data would be a custom implementation.

The reason why the gltf crate doesn't support export is because coming up with a generic export API is a non-trivial task. It is however a known issue, see gltf-rs/gltf#187.

[anderejd]

Here's an initial attempt with a minimal export example (triangle): gltf-rs/gltf#193

I haven't improved on that code since, so we could re-open the PR or pick the good parts and create something different.