bevy_mod_scripting VS bevy-inspector-egui

As someone who's become a core contributor to Bevy lately, while also doing contract work in Unity on the side, I obviously disagree with the idea that Rust isn't up to the task of game dev. The grass isn't greener on the Unity side, with a mountain of technical debt holding the engine back. (They're still using Boehm GC in 2024!) Bevy is a breath of fresh air just because it's relatively new and free of legacy. Using Rust instead of C++ is just one part of that. Bevy has a more modern design throughout: for instance, it has a relatively straightforward path to GPU-driven rendering in an integrated system, without having to deal with three incompatible render pipelines (BiRP, HDRP, URP).

What I find more interesting is the parts of the article that boil down to "Rust isn't the best language for rapid development and iteration speed". And that may well be true! I've long thought that the future of Bevy is an integrated Lua scripting layer [1]. You don't even need to get into arguments about the suitability of the borrow checker: it's clear that artists and designers aren't going to be learning Rust anytime soon. I'd like to see a world in which Rust is there for the low-to-mid-level parts that need performance and reliability, and Lua is there for the high-level logic that needs fast iteration, and it's all a nicely integrated whole.

Long-term, I think this world would actually put Bevy in a better place than the existing engines. Unity forces you into C# for basically everything, which is both too low-level for non-programmers to use and too high-level for performance-critical code (unless you have a source license, which no indie developer has). Unreal requires C++, which is even more difficult than Rust (IMO), or Blueprints, which as a visual programming language is way too high-level for anything but the simplest logic. Godot favors GDScript, which is idiosyncratic for questionable gain. I think Rust and Lua (or something similar) would put Bevy in a Goldilocks spot of having two languages that cover all the low-, mid-, and high-level needs well.

As for the other parts of the article, I disagree with the ECS criticism; ECS has some downsides, but the upsides outweigh the downsides in my view. I do agree that Bevy not having an official editor is an ongoing problem that desperately needs fixing. Personally, I would have prioritized the editor way higher earlier in Bevy's development. There is space_editor [2] now, which is something.

[1]: https://github.com/makspll/bevy_mod_scripting

[2]: https://github.com/rewin123/space_editor

So far, there are promising experiments like https://github.com/makspll/bevy_mod_scripting, but nothing's really caught fire in the community yet.

Interesting. Personally I find Rust-only pretty appealing, but people definitely have differing opinions: https://github.com/makspll/bevy_mod_scripting

With egui and some bevy related plugins you can get pretty close to a game engine editor, obviously missing a lot of things: https://github.com/jakobhellermann/bevy-inspector-egui

Like /u/tarkin25 already mentioned "egui" can be integrated into bevy. Bevy Inspector Egui is a plugin that not only provides a helpful way to inspect different entities in the world, but also re-exports "egui" for use.

Firstly, Bevy has an internal crate called bevy_reflect, and it can handle most of the things you would usually use reflection for. For example, https://github.com/jakobhellermann/bevy-inspector-egui exists which uses Bevy's internal reflect derive to make the values available via an egui-based UI. Changing simple values (like an f32, or a boolean) can be done at runtime, and if I remember correctly all you actually need to do is to add the plugin. Taking a look at the README https://github.com/bevyengine/bevy/tree/main/crates/bevy_reflect you can "patch" types with new values, iterate over struct fields, serialize + deserialize, and generally do stuff like that.

Yeah runtime editing is definitely a weakness at this point. An editor is definitely a part of our plans though! We'll likely break ground on it early this year. In the meantime https://github.com/jakobhellermann/bevy-inspector-egui provides some nice runtime editing / inspecting / editor-like tools.

Here is the example

Bevy-inspector-egui is a most have, I think this game would not have been possible without, abuse it,

What do you miss from scriptable objects that you don't get from a class that serializes to JSON? Global access (read only access shouldn't prevent this right)? The inspector (looks like egui can help there?

There are also some super interesting experiments with hot reloading, both with code and on the fly value modification.

The one in bevy is nowhere near the requirements of a desktop application-level editor. I don't plan to involve bevy there at all. egui looks quite usable for low-level debug UI, though, especially with this crate.