Plugins (Pro/Mobile-Only Feature)

Unity has extensive support for Plugins, which are libraries of native code written in C, C++, Objective-C, etc. Plugins allow your game code (written in Javascript, C# or Boo) to call functions from these libraries. This feature allows Unity to integrate with middleware libraries or existing C/C++ game code.

Note: On the desktop platforms, plugins are a pro-only feature. For security reasons, plugins are not usable with webplayers.

In order to use a plugin you need to do two things:-

• Write functions in a C-based language and compile them into a library.
• Create a C# script which calls functions in the library.

The plugin should provide a simple C interface which the C# script then exposes to other user scripts. It is also possible for Unity to call functions exported by the plugin when certain low-level rendering events happen (for example, when a graphics device is created), see the Native Plugin Interface page for details.

Here is a very simple example:

C File of a Minimal Plugin:

float FooPluginFunction () { return 5.0F; }

C# Script that Uses the Plugin:

using UnityEngine;using System.Runtime.InteropServices;class SomeScript : MonoBehaviour {   #if UNITY_IPHONE || UNITY_XBOX360   // On iOS and Xbox 360 plugins are statically linked into   // the executable, so we have to use __Internal as the   // library name.   [DllImport ("__Internal")]   #else   // Other platforms load plugins dynamically, so pass the name   // of the plugin's dynamic library.   [DllImport ("PluginName")]   #endif   private static extern float FooPluginFunction ();   void Awake () {      // Calls the FooPluginFunction inside the plugin      // And prints 5 to the console      print (FooPluginFunction ());   }} 

Note that when using Javascript you will need to use the following syntax, where DLLName is the name of the plugin you have written, or "__Internal" if you are writing statically linked native code:

@DllImport (DLLName)static private function FooPluginFunction () : float {};

Creating a Plugin

In general, plugins are built with native code compilers on the target platform. Since plugin functions use a C-based call interface, you must avoid name mangling issues when using C++ or Objective-C.

For further details and examples, see the following pages:-

• Building Plugins for Desktop Platforms

• Building Plugins for iOS

• Building Plugins for Android

Further Information

• Native Plugin Interface - this is needed if you want to do rendering in your plugin.
• Mono Interop with native libraries.
• P-invoke documentation on MSDN.

Page last updated: 2012-02-02