function2
flecs
function2 | flecs | |
---|---|---|
7 | 48 | |
530 | 5,530 | |
- | - | |
4.7 | 9.6 | |
2 months ago | 5 days ago | |
C++ | C | |
Boost Software License 1.0 | MIT License |
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function2
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Callbacks in embedded | heapless environment
Fixed size function wrappers are not only limited and also a waste of space. Use a configurable function wrapper like fu2 with a stack allocator and set small object optimizer capacity to 0.
- Scriptable Headless Player Bots and independent ECS in a Custom UE C++ Server for MMO(RPG)s.
- A custom C++ server for the Unreal Engine 5, optimized for MMO(RPG)s.
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A simple std::function alternative that never allocates
std::function wasn't cutting it for me, but I ended up going with fu2::function. It comes with a lot of features (almost too many), but the header size and compile times are comparable to , and it fit my needs pretty well.
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Idle: an asynchronous and hot-reloadable C++ dynamic component framework
Thank you, function2 is also used heavily in Idle as a type-erasure backend for continuable that is the primary asynchronous task abstraction.
- Should std::function's move assignment operation be noexcept?
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Orthodox C++
You can write your own std::function, too, nor is it the only STL type that can take a capturing lambda (std::packaged_task for example).
A capturing lambda is just a class with an operator(). It's complicated to do what std::function does, but fully possible.
In fact, custom std::function replacements have better lambda support than std::function itself. Such as unique_function in https://github.com/Naios/function2 which can handle non-copyable lambdas.
flecs
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ECS, Finally
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
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Databases are the endgame for data-oriented design
Flecs does just that: https://ajmmertens.medium.com/why-it-is-time-to-start-thinking-of-games-as-databases-e7971da33ac3
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What's your way to create an ECS?
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.
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Introducing Ecsact
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.
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Prolog for future AI
Repository: https://github.com/SanderMertens/flecs
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An in-game query engine heavily inspired by prolog
This is the project: https://github.com/SanderMertens/flecs (query engine implementation lives here: https://github.com/SanderMertens/flecs/tree/master/src/addons/rules)
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What are the limits of blueprints?
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.
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What's the hot tech stack these days?
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.
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Bevy and WebGPU
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...
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any resources for expanding on ECS?
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 are some alternatives?
Inja - A Template Engine for Modern C++
entt - Gaming meets modern C++ - a fast and reliable entity component system (ECS) and much more
FunctionalPlus - Functional Programming Library for C++. Write concise and readable C++ code.
JUCE - JUCE is an open-source cross-platform C++ application framework for desktop and mobile applications, including VST, VST3, AU, AUv3, LV2 and AAX audio plug-ins.
LSHBOX - A c++ toolbox of locality-sensitive hashing (LSH), provides several popular LSH algorithms, also support python and matlab.
Boost - Super-project for modularized Boost
stx-btree - OBSOLETE, contained in https://github.com/tlx/tlx - STX B+ Tree C++ Template Classes -
SDL - DEPRECATED: Official development moved to GitHub
Hashmaps - Various open addressing hashmap algorithms in C++
Folly - An open-source C++ library developed and used at Facebook.
Learn Project - go study
Seastar - High performance server-side application framework