Question How to use a header-only C++ library in Unity WITHOUT using a dll?

Hello, I have a very specific problem. I need to implement a header-only C++ library named Eigen for my WebGL unity build. I have found this solution https://longqian.me/2017/02/24/eigen-in-unity/. Which does not apply to my case, as dynamic library is not supported with WebGL.
I have also attempted to use the whole Eigen library as a plugin, and reference it in another native plugin cpp file, then calling the cpp functions from c#. However attempting to compile with the library in Unity caused an error of "Plugins colliding with each other" Can anyone give me some ideas or solutions for similar problems? Thanks a lot!

 

I think for WebGL you would need to compile the C++ code with something like Emscripten, then include the resulting javascript into your app and call it from Unity.

 

WHAAAAAT!!!!? Are you serious?! This didn't use to be a thing for WebGL.

Time to see if I can get my old MS-DOS, PalmOS native C/C++ project (KurtMaster2D) to build for WebGL.

I already have all games 100% operational on PC, Mac, iOS and Android and Android TV thanks to Unity's awesomeness... if I can stand this up in WebGL my target circle will be complete.

 

Thanks a lot for the speedy reply! Indeed that was what I have been trying to do, I managed to get it working after trimming the files which are intended for different platforms. However this manually trimming seems somewhat problematic since I will be working with others in this project in the future, is there a cleaner way for me to pack them into something like a .lib? Again, thanks a lot!

 

Sorry, scratch my previous question. I have found a simpler way to present my problem. Since Unity somehow compiles my cpp files, is there anyway to interface this process? Via perhaps a cmake file or something of the sort to solve the dependency problem without placing everything in the Unity folder.

 

If this is a header-only library, it can't be directly compiled into a dll. Headers aren't compiled by themselves, they must be included into C/CPP files which call the functions in the header.

You need to create a .cpp file with exported functions that wrap the header library functions you want to call from C#. These wrapper functions also must be exported as C functions, you cannot pass C++ classes through the interop layer. If the library API is C++ (using templates, inheritance, etc), you need to wrap a C API on top of it too.

 

Could you speak more to this process? Is a .bc simply another form of .lib or .a file?

I actually would prefer to combine all my C/C++ files into a library (the way I do for Mac, PC, Android and iOS presently) rather than restructuring to include the files directly.

Is it this process: ?

https://groups.google.com/g/llvm-dev/c/Jl_SXbgXcWk

Or could you perhaps point me to whatever it actually is?