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:-
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.