4 ms·

I had a nice comparison because I first tried to do a native implementation in C++ and - wanting to do some custom low-level "stuff" for my simulation actor sys

I had a nice comparison because I first tried to do a native implementation in C++ and - wanting to do some custom low-level "stuff" for my simulation actor system (related to allocation and networking) - I ran into so many footguns that it slowed me tremendously. As soon as I tried to do the same with Rust, it was a breeze and I was able to write a lot of unsafe code that does very particular things that I need, while exposing a completely safe API for the rest of the engine and game. Being then able to also use Rust in the browser quite seamlessly with WASM allowed me to have a super straightforward and high-perf communication channel between the simulation backend and browser UI. The only real Rust disadvantage that hurts a lot is compile times. Sometimes I do fight types/the borrow checker, but only when I try to do weird things, in general I perceive it as a huge help in scaffolding things.

segmondy 8y ago
Very nice, how did you decide on your simulation? did you build a generic simulation engine you can reuse, or is your simulation tightly coupled to the objects you are simulating? It's fun seeing this, I have been recently thinking of a simulation game and wondering if to use a generic simulation library such as SimPy
- theanzelm 8y ago
  I build a simulation engine, based on a high performance distributed actor system library I wrote for just this purpose. It is generic, but a lot of the performance trade-offs are with Citybound's needs as the main driver.
  - izend 8y ago
    I see you didn't use Actix or even Tokio, could you please explain why?
    - theanzelm 8y ago
      Their actor implementation / event loop works on a higher level than mine. Mine is super simplistic intentionally to offer high performance. Being optimised for cache locality, processing similar actors in batches, using custom allocators and having encoding-free communication, it has many parallels to data-driven game engine design or even entity component systems.
      - izend 8y ago
        cargo +nightly run of the examples in your Kay project appears to be broken, I'd love to explore using it in a future project.
384028345 8y ago
First time I hear about compile times being an issue with Rust. Is that a general problem with bigger projects or can you identify language features that add specifically to the problem?
- felipellrocha 8y ago
  First compilation is slow. After that it’s much better during development times. This can mean that ci can take a ton of time if you don’t do even the smallest bit of optimization. Otherwise, it’s a solid language choice. L
  - theanzelm 8y ago
    As a point of reference "warmed up" compilation for me still takes ~1minute. Bearable for general work, horrible for quick tweaks or UI-related work.
    - infogulch 8y ago
      I've heard that long warm compilation times can be mitigated by breaking up code into separate modules so it doesn't recompile e.g. the actor system every time you adjust a layout. Basically caching works best on the module boundary. Is this something you've explored?
      - z0mbie42 8y ago
        +1 I've splitted a 20k+LOC Rust project into multiple crates and compilation time improved a lot (still slow compared to other languages) but it's now manageable.
      - theanzelm 8y ago
        Yes, I factored out quite a bit of generic parts of the engine into libraries and took some steps to cut down on number of generics being instanced (which was one of the main drivers of compile time). Now I'm left with pretty much the game core, which is highly interdependent and thus nearly impossible to break up into crates (they can't mutually depend on each other). And it's still kinda slow.
taneq 8y ago
Thanks for your answers here, I'm definitely going to look more closely at Rust for my next project!

segmondy 8y ago

Very nice, how did you decide on your simulation? did you build a generic simulation engine you can reuse, or is your simulation tightly coupled to the objects you are simulating? It's fun seeing this, I have been recently thinking of a simulation game and wondering if to use a generic simulation library such as SimPy

theanzelm 8y ago
I build a simulation engine, based on a high performance distributed actor system library I wrote for just this purpose. It is generic, but a lot of the performance trade-offs are with Citybound's needs as the main driver.
- izend 8y ago
  I see you didn't use Actix or even Tokio, could you please explain why?
  - theanzelm 8y ago
    Their actor implementation / event loop works on a higher level than mine. Mine is super simplistic intentionally to offer high performance. Being optimised for cache locality, processing similar actors in batches, using custom allocators and having encoding-free communication, it has many parallels to data-driven game engine design or even entity component systems.
    - izend 8y ago
      cargo +nightly run of the examples in your Kay project appears to be broken, I'd love to explore using it in a future project.

384028345 8y ago

First time I hear about compile times being an issue with Rust. Is that a general problem with bigger projects or can you identify language features that add specifically to the problem?

felipellrocha 8y ago
First compilation is slow. After that it’s much better during development times. This can mean that ci can take a ton of time if you don’t do even the smallest bit of optimization. Otherwise, it’s a solid language choice. L
- theanzelm 8y ago
  As a point of reference "warmed up" compilation for me still takes ~1minute. Bearable for general work, horrible for quick tweaks or UI-related work.
  - infogulch 8y ago
    I've heard that long warm compilation times can be mitigated by breaking up code into separate modules so it doesn't recompile e.g. the actor system every time you adjust a layout. Basically caching works best on the module boundary. Is this something you've explored?
    - z0mbie42 8y ago
      +1 I've splitted a 20k+LOC Rust project into multiple crates and compilation time improved a lot (still slow compared to other languages) but it's now manageable.
    - theanzelm 8y ago
      Yes, I factored out quite a bit of generic parts of the engine into libraries and took some steps to cut down on number of generics being instanced (which was one of the main drivers of compile time). Now I'm left with pretty much the game core, which is highly interdependent and thus nearly impossible to break up into crates (they can't mutually depend on each other). And it's still kinda slow.

taneq 8y ago

Thanks for your answers here, I'm definitely going to look more closely at Rust for my next project!