flecs VS papers

I've also been enjoying building My First Game™ in Bevy using ECS. The community around Bevy really shines, but Flecs (https://github.com/SanderMertens/flecs) is arguably a more mature, open-source ECS implementation. You don't get to write in Rust, though, which makes it less cool in my book :)

I'm not very proud of the code I've written because I've found writing a game to be much more confusing than building websites + backends, but, as the author notes, it certainly feels more elegant than OOP or globals given the context.

I'm building for WASM and Bevy's parallelism isn't supported in that context (yet? https://github.com/bevyengine/bevy/issues/4078), so the performance wins are just so-so. Sharing a thread with UI rendering suuucks.

If anyone wants to browse some code or ask questions, feel free! https://github.com/MeoMix/symbiants

Flecs does just that: https://ajmmertens.medium.com/why-it-is-time-to-start-thinking-of-games-as-databases-e7971da33ac3

I'm trying to optimize my workflow as much as possible, and came across this thing called an ECS. After doing a little bit more digging I found some decent guides on how you would make one, I also found one premade called FLECS. FLECS is nice and all, but I was looking for something more simple that just has the bare bones of what I need and is also configurable. I haven't been able to really find anything like that, so I was wondering if anyone had an example of maybe their way of implementing an ECS. I know how to go about it, but I'm unsure of exactly what the code would look like.

Since we wanted a common game simulation that would be on both the server and the client we looked into a few libraries that would fit our ECS needs. It was decided we were going to write this common part of our game in C++, but rust was considered. C++ was a familiar language for us so naturally EnTT and flecs came up right away. I had used EnTT before, writing some small demo projects, so our choice was made based on familiarity. In order to integrate with Unity we created a small C interface to communicate between our simulation code and Unity’s C#. Here’s close to what it looked like. I removed some parts for brevity sake.

Repository: https://github.com/SanderMertens/flecs

This is the project: https://github.com/SanderMertens/flecs (query engine implementation lives here: https://github.com/SanderMertens/flecs/tree/master/src/addons/rules)

There's also a performance question. While we can now use Blueprint nativization to convert Blueprints to C++ the result will be a fairly naive version, fast enough for most purposes but not if you're trying to push every bit of performance. This is where you're looking at making sure you're hitting things such as using the CPU cache as well as possible for an ECS system (Look at ENTT or Flecs if you want to see what they're about and why you'd want one), or a system needing to process massive amounts of data quickly such as the Voxel Plugin.

If I knew C++ and I'd heard about it before I started my current project, I would have been tempted to use this https://github.com/SanderMertens/flecs which can be built to WASM. Of course you still need JavaScript in the front end to link to the WASM part. I've recently been using esbuild to bundle my front end code, which does a pretty similar job to webpack, but is a bit faster.

When do think bevy will support entity-entity relationships ? https://github.com/bevyengine/bevy/issues/3742.

Flecs ECS already supports this: https://github.com/SanderMertens/flecs/blob/master/docs/Rela...

For a modern engine you’re probably best looking at Unity’s DOTS. You may also want to check out some of the different open source ECS libraries such as flecs and EnTT are two popular ones for C++, but there’s lots of them. Largely you’ll see lots of different approaches taken, all with their own pros and cons. Not all of them will be performant (some focus more on the design benefits) while others will be optimised for certain use cases. What you should prioritise will depend on your specific needs.

What's fun is, because everything is decided in papers, we can find out why! https://github.com/cplusplus/papers/issues/884

Accepted paper here: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p20...

> The proposed std::print function improves usability, avoids allocating a temporary std::string object and calling operator<< which performs formatted I/O on text that is already formatted. The number of function calls is reduced to one which, together with std::vformat-like type erasure, results in much smaller binary code (see § 13 Binary code).

Additionally,

> Another problem is formatting of Unicode text:

> std::cout << "Привет, κόσμος!";

> If the source and execution encoding is UTF-8 this will produce the expected output on most GNU/Linux and macOS systems. Unfortunately on Windows it is almost guaranteed to produce mojibake despite the fact that the system is fully capable of printing Unicode

See https://github.com/cplusplus/papers/issues/557

Bringing editions to C++ failed, and I am not aware of anyone trying to tackle the issues https://github.com/cplusplus/papers/issues/631

(I could be wrong though! I follow the committee more than you may guess, but not as much as to think I know everything about what's going on.)

GitHub would not be relevant in this respect because:

* It's owned by a (single) commercial corporation, Microsoft.

* There is censorship both by content and in some respects by country of origin.

* The code is closed.

but otherwise it's an interesting idea.

The C++ standardization committee uses GitHub to track papers submitted to them, see:

https://github.com/cplusplus/papers

There was no non-approval. The facility needs more work, and the authors (and the committee) were focusing on getting print/format done first. I hope that the paper will be worked on again in the future. We will be happy to review it once there is a revision (see github for history)

For more details on what we did at the 2023-06 Varna meeting, the [GitHub issue](https://github.com/cplusplus/papers/issues/328) associated with the paper has a summary.

You subscribe to the Github issue of the proposal: https://github.com/cplusplus/papers/issues