In addition to the public C# APIs for writing managed code, Unity provides a smaller native interface, which you can use to access Unity Editor and Engine functionality from your native plug-insA 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.
The native interfaces are a set of C or C++ compatible header (.h) files incuded as part of an Editor installation. The files are in the PluginAPI folder, which you can find in the following locations:
<UnityInstallPath>\Editor\Data\PluginAPI
Contents\PluginAPI
Each header file contains additional documentation as code comments within it. For more information on getting started with implementing the native interfaces, refer to the code comments in the main header file IUnityInterface.h.
All Unity native plug-inA platform-specific native code library that is created outside of Unity for use in Unity. Allows you can access features like OS calls and third-party code libraries that would otherwise not be available to Unity. More info
See in Glossary API header files are compatible with plug-ins written in C++, but only some are compatible with plug-ins written in C.
Files that aren’t C-compatible report the error "This file cannot be compiled in a C environment" if you attempt to compile them as C. You’ll also find the corresponding check in the header file source:
#ifndef __cplusplus
#error "This file cannot be compiled in a C environment"
#endif
To handle main Unity events, a plug-in must export UnityPluginLoad and UnityPluginUnload functions. IUnityInterfaces enables the plug-in to access these functions, which you can find in IUnityInterface.h in the plug-in API.
The following example uses IUnityInterfaces to load the IUnityGraphics interface into a pointer. This is a standard method you can repeat to load other interfaces from the native plug-in API:
#include "IUnityInterface.h"
#include "IUnityGraphics.h"
// Unity plugin load event
extern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API
UnityPluginLoad(IUnityInterfaces* unityInterfaces)
{
IUnityGraphics* graphics = unityInterfaces->Get<IUnityGraphics>();
}