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Unity Engine

Introduction to native plug-in API

Locate the native plug-in API files and import them into your native plug-in.
Read time 2 minutesLast updated 12 days ago
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-ins.

Plugin API folder

The native interfaces are a set of C or C++ compatible header (.h) files included as part of the Unity Editor installation. The files are located in the 
PluginAPI
folder, which varies depending on the operating systems you're using:
  • Windows: 
    <UnityInstallPath>\Editor\Data\PluginAPI
    .
  • macOS: Right-click the Unity application, and select Show Package Contents. The headers are located in the 
    Contents/Resources/PluginAPI
    folder.
  • Linux: 
    <UnityInstallPath>/Editor/Data/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
.

Interface compatibility

All Unity native plug-in 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

Interface registry

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 eventextern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API    UnityPluginLoad(IUnityInterfaces* unityInterfaces){    IUnityGraphics* graphics = unityInterfaces->Get<IUnityGraphics>();}

Additional resources