Okay, I think I almost did the same in Rust what Alon described. vanger-rs
now compiles as static library (.a) with emscripten triple. I use this
static library to link with original C++ game. So I have *.o files from
vangers, and librusty_vangers.a (which provides rendering on wgpu). I link
them with emcc, and it produce wasm without any error!
Also I do the same with native build - it works fine.
However, when I tries to run it fails with assertion.
On RUST side I have the following code:
#[no_mangle]
pub static rv_api_1: i32 = 1;
On C++ side I have the following code:
extern int32_t rv_api_1;
// ...
if(rv_api_1 != 1){
printf("Invalid libvangers_ffi version expected 1, actual %d\n",
rv_api_1);
// abort();
}
When I run it, I have following output:
Invalid libvangers_ffi version expected 1, actual 0
For me it looks like static initializer from RUST didn't run. Because if I
comment the abort(); seems integration works fine. Native build works
correctly...
Do you have any idea why so?
ср, 19 янв. 2022 г. в 00:36, Alon Zakai <[email protected]>:
>
>
> On Fri, Jan 14, 2022 at 11:08 AM Александр Гурьянов <[email protected]>
> wrote:
>
>> Let's look closer to my case. I ported C++ game Vangers to the web (
>> https://www.gamepix.com/play/vangers). Vangers community did big work to
>> integrate vange-rs (rust 3d render, based on wgpu) and Vangers game. It
>> works as follow:
>> 1. Vange-rs provide c ffi interface
>> 2. Vange-rs compiled with rust to static library
>> 3. Vangers linked with Vanger-rs to executable
>>
>> Now I want to port vangers + (vange-rs render) to the web. wgpu didn't
>> support wasm32-unknown-emscripten, I added experimental support for
>> emscripten and it works. BUT, wgpu is developing to fast, so my changes
>> become outdated very fast :)
>>
>> When I implement support for emscripten, I only disabling wasm32-unknown
>> rules and uses native code paths everywhere. So, it's little bit strange,
>> to work with emscripten you need to disable workarounds for wasm32.
>> emscripten emulates native platform, so code that correctly uses posix
>> system should work also in emscripten.
>>
>> Maybe there is any way to just use native static library and link it with
>> emscripten? Like this:
>> 1. Compile vange-rs static library (with native triple)
>> 2. Compile vangers project with emscripten
>> 3. Link 1+2 with emscripten
>>
>>
> (1) would compile to x86, though, I think? We have to have wasm to link
> with emscripten.
>
>
>> for (1.) I can't use emscripten triple because of #[cfg] rules for wasm32
>> target, they select wrong code path (non-native).
>>
>>
> Hmm, I don't know enough rust to know what fixing that would mean...
>
> Overall for an emscripten port I think we would want to use a native build
> as much as possible? That is, ideally you would *not* use vange-rs/WebGPU,
> but one of the native rendering paths (OpenGL of some flavor? Or perhaps
> they have Dawn/WebGPU support?). And you would need to tell rust to use the
> emscripten triple while doing so.
>
> That should work, in theory. If it doesn't and Rust has some issues with
> how it invokes emcc to link, then the workaround could be what I mentioned
> for Zig and C before: get Rust to link to a static library, and then run
> emcc manually on that.
>
> (Alternatively, in theory someone could look into supporting wasm-bindgen
> + emscripten.)
>
> - Alon
>
>
>> пт, 14 янв. 2022 г. в 07:54, Alon Zakai <[email protected]>:
>>
>>> Thanks, good to know at least 2 people would read a post about this :)
>>> I'll try to find time for it.
>>>
>>> About Rust, I haven't had time to look into it yet. My general hope is
>>> that the same model as for C and Zig could work:
>>>
>>> 1. Tell Rust to use the emscripten wasm triple.
>>> 2. Tell Rust to compile to object files (or a static library,
>>> basically), and *not* to link them.
>>> 3. The user runs emcc on those object files, linking them.
>>>
>>> The nice thing in this model is that C/Zig/Rust does not need to be
>>> aware of emcc at all here (aside from telling LLVM to use the emscripten
>>> triple). And it's easy to do this, at least in C and Zig (although there
>>> are some subtle ABI questions).
>>>
>>> This is actually the main thing I wanted to do before writing the post -
>>> ideally I'd have a Rust demo alongside C and Zig - so if someone figures
>>> that out, let me know!
>>>
>>> - Alon
>>>
>>>
>>> On Thu, Jan 13, 2022 at 2:06 AM Александр Гурьянов <[email protected]>
>>> wrote:
>>>
>>>> +1 for blog post. Not clear how I can use it with rust, e.g. can I
>>>> compile static lib with target --wasm32-unknown-unknown and then link using
>>>> emscripten? The main problem with RUST is that it even can't compile with
>>>> --wasm32-unknown-emscipten (because of lib dependencies that not support
>>>> emscripten)
>>>>
>>>> чт, 13 янв. 2022 г. в 16:46, Floh <[email protected]>:
>>>>
>>>>> That's a very useful gist, Alon! I think that blog post would be much
>>>>> appreciated by a lot of people who like to tinker with other languages :)
>>>>>
>>>>> On Wednesday, 12 January 2022 at 19:32:04 UTC+1 [email protected]
>>>>> wrote:
>>>>>
>>>>>> On Sat, Dec 25, 2021 at 6:02 AM Floh <[email protected]> wrote:
>>>>>>
>>>>>>> Ah, language and toolchain interoperability, one of my favourite
>>>>>>> topics ;)
>>>>>>>
>>>>>>> Zig has nearly the same problems as Rust: it allows to compile to
>>>>>>> WASM, it has both a WASI and Emscripten target, with the WASI target
>>>>>>> working out of the box, but I gave up on the Emscripten target because I
>>>>>>> just couldn't get it to work.
>>>>>>>
>>>>>>
>>>>>> I wrote up a demo of Zig + Emscripten here:
>>>>>>
>>>>>> https://gist.github.com/kripken/58c0e640227fe5bac9e7b30100a2a1d3
>>>>>>
>>>>>> That uses GLES3 and Asyncify from Emscripten, so it's a small program
>>>>>> but it uses interesting features.
>>>>>>
>>>>>> The gist also shows using C in the same way, where Emscripten is just
>>>>>> the linker, not the frontend.
>>>>>>
>>>>>> I've been meaning to do the same with Rust and write a blogpost about
>>>>>> all 3 but haven't found the time...
>>>>>>
>>>>>> - Alon
>>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> IMHO it would be great if the Javascript shims and interop could be
>>>>>>> somehow split out of the Emscripten SDK into a separate, smaller
>>>>>>> "webapi-wasm-tools" SDK which could be better integrated with other
>>>>>>> language toolchains. The goal should be that other programming languages
>>>>>>> can benefit from the work that went into the Emscripten SDK to access
>>>>>>> web
>>>>>>> APIs like WebGL, WebGPU, WebAudio etc... up to "EM_JS()" functionality,
>>>>>>> instead of having to duplicate this work, or requiring a separate
>>>>>>> installation of the whole Emscripten SDK.
>>>>>>>
>>>>>>> There's a very promising project https://github.com/schellingb/wajic
>>>>>>> by Bernhard Schelling which has the same goals and which was used to
>>>>>>> port
>>>>>>> Mattias Gustavsson's DOS-like library to the web:
>>>>>>> https://mattiasgustavsson.com/wasm/
>>>>>>>
>>>>>>> Anyway... just my 2 cents :)
>>>>>>> -Floh.
>>>>>>> On Friday, 24 December 2021 at 15:16:23 UTC+1 caiiiycuk wrote:
>>>>>>>
>>>>>>>> Hi! Just want to share my experiment with using Rust and
>>>>>>>> WebAssembly. I tried to port Vange-rs project (rust + wgpu) to
>>>>>>>> browser. I
>>>>>>>> used emscripten and unknown platforms. Both finally works, but have
>>>>>>>> lot of
>>>>>>>> obstacles. I am very sad about support level of emscripten in Rust,
>>>>>>>> hope it
>>>>>>>> will change at some day.
>>>>>>>>
>>>>>>>>
>>>>>>>> https://caiiiycuk.medium.com/vange-rs-webassembly-in-rust-498e2f960a04
>>>>>>>>
>>>>>>> --
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