Version: 2021.3
Language : English
Call C/C++/C# functions from Unity C# scripts
Create callbacks between Unity C#, JavaScript, and C/C++/C# code

Compile a static library as a Unity plug-in

You can compile libraries with Emscripten and use the libraries in Unity. It can be more beneficial to call functions from libraries that encapsulate C++ code rather than C++ code directly from the plug-inA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
See in Glossary
directory. The benefits include:

  • Your code is easier to integrate with your Web Unity project.
  • Your code can perform better than if you call functions from C++ code, especially for larger libraries.
  • You can reuse the code in various projects.

Steps to use a static library in Unity

To compile a static library that you can use as a Unity plug-in:

  1. Download the Emscripten SDK
  2. Configure any existing project scripts
  3. Update your compiler options
  4. Compile and import your static library files
  5. Call your static library functions from C# scripts

1. Download the Emscripten SDK

You must download the Emscripten SDK that matches your version of Unity.

To find the appropriate version of Emscripten for your Unity version, refer to Web native plug-ins for Emscripten.

For download links and more information about how to install the Emscripten SDK, refer to Download and install (Emscripten).

2. Configure any existing project scripts

Emscripten works as a replacement for the gcc or clang compiler. If you have existing C/C++ code, you need to make the following changes in your C++ project:

  • Use “emcc” as the C/C++ compiler
  • Use “emar” as the static linker

For more information, refer to the Emscripten documentation on Compiling and Running Projects.

3. Update your compiler options

You might need to add some compiler options to your C/C++ project if your Unity project has the following Player settings (menu: Edit > Project Settings > Player).

Property Description
Enable Exceptions If this property is set to None, add the compiler option “-fno-exceptions”.
Enable Native C/C++ Multithreading If this property is enabled, include the compiler option “-pthread”.
Enable WebAssembly 2023 If this property is enabled, include the following compiler options:
  • “-fwasm-exceptions”
  • “-sSUPPORT_LONGJMP=wasm”
  • “-mbulk-memory”
  • “-mnontrapping-fptoint”
  • “-msimd128”
  • “-msse4.2”

4. Compile and import your static library files

Compile your static library files and then import your files into your Unity project in the Assets/Plugins folder.

Note: If you don’t have a Plugins folder, you need to create your own.

5. Call your static library functions from Unity C# scripts

You can call your static library functions from your Unity C# scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary
. The way to call the functions is the same as if you call a C or C++ function from C# scripts. For an example, refer to Call C/C++/C# functions from Unity C# scripts.

Additional resources

Call C/C++/C# functions from Unity C# scripts
Create callbacks between Unity C#, JavaScript, and C/C++/C# code