Add bevy_fbx, an FBX loader based on ufbx

[VitalyAnkh]

Objective

• Support FBX asset loading via ufbx
• Fixes Support FBX file loading #15705

Solution

• Add bevy_fbx, an FBX loader based on ufbx.
• Why using ufbx? It is a thoroughly tested, single-file FBX loader that now powers Godot’s native FBX importer and Blender’s new official importer; it also ships with first-party Rust bindings.

Testing

• example load_fbx, asset_loading.

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[github-actions]

The generated examples/README.md is out of sync with the example metadata in Cargo.toml or the example readme template. Please run cargo run -p build-templated-pages -- update examples to update it, and commit the file change.

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[mockersf]

as it uses a native dependency, I don't think it should be part of the default features

[pcwalton]

Agreed with @mockersf. FBX support would be very nice, but C++ dependencies add a lot of pain to the out-of-the-box experience in many cases, so let's make it opt-in.

[github-actions]

The generated examples/README.md is out of sync with the example metadata in Cargo.toml or the example readme template. Please run cargo run -p build-templated-pages -- update examples to update it, and commit the file change.

[VitalyAnkh]

ufbx is a self-contained FBX loader made up of just two files—ufbx.c and ufbx.h. It depends only on libc and has no other significant prerequisites, so it’s much simpler to build than most C++ or Rust libraries. That said, I’m happy to make FBX support an optional feature if that’s the community consensus.

[github-actions]

You added a new feature but didn't add a description for it. Please update the root Cargo.toml file.

[IceSentry]

I know it's still WIP, but it would be way easier to review if the main load() function was split into multiple functions. A bit like how bevy_gltf has load_materials, load_image, load_node, etc.

Also, once the PR is ready to merge I think it should only have one .fbx file in the asset folder. It's a good feature to have but we need to keep the size of the repo in check.

[VitalyAnkh]

I will refactor the main load() function following bevy_gltf. And there will be only one cube.fbx file in the repo, and I have already added a scene_viewer_fbx example to inspect other fbx files easily. Thanks for the nice advice!

[github-actions]

You added a new feature but didn't add a description for it. Please update the root Cargo.toml file.

[pcwalton]

Thought: if ufbx is just a C library, can we use c2rust on it so that users don't need a C compiler installed?

[BenjaminBrienen]

I suspect that major portions of this contribution are AI generated. Em dash, overcommenting, commenting about "in the actual implementation..." and some other points discussed on Discord with other members. Nominating to close as per bevyengine/bevy-website#2204

Please correct me if I'm wrong!

[VitalyAnkh]

I admit I made use of AI tools a lot to help me in this PR. I don't mean to deliberately violate community policies when I started in June 8, at that time Bevy Org's AI policy doesn't even exist, and I didn't know about it until today. I will close this in accordance with the AI policy, and I commit to adhering to the community code of conduct.

Anyway, the PR is in good shape now (especially good animation support) and if the AI policy is released earlier, I will follow the policy and won't use any AI tools.

[mholiv]

As someone who has been following this, but isn’t as familiar with the core workflow as I would like, what is happening?

Will this be merged, or is it dead, or does it need more feedback?

[BenjaminBrienen]

Many Bevy maintainers want a version of this, so someone can contribute a new PR that implements it in a similar way.

[mholiv]

@BenjaminBrienen Beyond this PR including AI work did you find and architectural flaws with the implementation? I might give this a shot in early October with this as a reference. Maybe with @VitalyAnkh support if they are up for it.

[BenjaminBrienen]

My review and opinion is not the most valuable, but I think basing it on ufbx like this is a good idea. It is a good direction.

[VitalyAnkh]

@mholiv I could help you with a new bevy_fbx crate based on ufbx, without the interverntion of AI. I'm still interested in fbx and passionated with bevy.

[mholiv]

Or it might make sense for you to take lead here @VitalyAnkh given you know the code base as it is. I am just a passionate dev. Who want's to see the engine improve. That and the 3D artist I am working with REALLY isn't a fan of gltf lol.

[james7132]

My review and opinion is not the most valuable, but I think basing it on ufbx like this is a good idea. It is a good direction.

I would be in support of this, provided this remains as a optional feature if it is using ufbx. We generally try to keep non-platform C/C++ build dependencies out of the default.