Platform Dependent Compilation

Unity includes a feature named "Platform Dependent Compilation". This consists of some preprocessor directives that let you partition your scripts to compile and execute a section of code exclusively for one of the supported platforms.

Furthermore, you can run this code within the Editor, so you can compile the code specifically for your mobile/console and test it in the Editor!

Platform Defines

The platform defines that Unity supports for your scripts are:

UNITY_EDITOR	Define for calling Unity Editor scripts from your game code.
UNITY_STANDALONE_OSX	Platform define for compiling/executing code specifically for Mac OS (This includes Universal, PPC and Intel architectures).
UNITY_DASHBOARD_WIDGET	Platform define when creating code for Mac OS dashboard widgets.
UNITY_STANDALONE_WIN	Use this when you want to compile/execute code for Windows stand alone applications.
UNITY_WEBPLAYER	Platform define for web player content (this includes Windows and Mac Web player executables).
UNITY_WII	Platform define for compiling/executing code for the Wii console.
UNITY_IPHONE	Platform define for compiling/executing code for the iPhone platform.
UNITY_ANDROID	Platform define for the Android platform.
UNITY_PS3	Platform define for running PlayStation 3 code.
UNITY_XBOX360	Platform define for executing Xbox 360 code.
UNITY_NACL	Platform define when compiling code for Google native client (this will be set additionally to UNITY_WEBPLAYER).
UNITY_FLASH	Platform define when compiling code for Adobe Flash.

Note: These defines were introduced at version 3.0.

Also you can compile code selectively depending on the version of the engine you are working on. Currently the supported ones are:

UNITY_2_6	Platform define for the major version of Unity 2.6.
UNITY_2_6_1	Platform define for specific version 1 from the major release 2.6.
UNITY_3_0	Platform define for the major version of Unity 3.0.
UNITY_3_0_0	Platform define for the specific version 0 of Unity 3.0.
UNITY_3_1	Platform define for major version of Unity 3.1.
UNITY_3_2	Platform define for major version of Unity 3.2.
UNITY_3_3	Platform define for major version of Unity 3.3.
UNITY_3_4	Platform define for major version of Unity 3.4.
UNITY_3_5	Platform define for major version of Unity 3.5.

Note: For versions before 2.6.0 there are no platform defines as this feature was first introduced in that version.

Testing precompiled code.

We are going to show a small example of how to use the precompiled code. This will simply print a message that depends on the platform you have selected to build your target.

First of all, select the platform you want to test your code against by clicking on File -> Build Settings. This will bring the build settings window to select your target platform.

Select the platform you want to test your precompiled code against and press the Switch Editor button to tell Unity which platform you are targeting.

Create a script and copy/paste this code:

JavaScript Example:

function Awake() {
  #if UNITY_EDITOR
    Debug.Log("Unity Editor");
  #endif

  #if UNITY_IPHONE
    Debug.Log("Iphone");
  #endif

  #if UNITY_STANDALONE_OSX
    Debug.Log("Stand Alone OSX");
  #endif

  #if UNITY_STANDALONE_WIN
    Debug.Log("Stand Alone Windows");
  #endif	
}

C# Example:

using UnityEngine;
using System.Collections;

public class PlatformDefines : MonoBehaviour {
  void Start () {

    #if UNITY_EDITOR
      Debug.Log("Unity Editor");
    #endif

    #if UNITY_IPHONE
      Debug.Log("Iphone");
    #endif

    #if UNITY_STANDALONE_OSX
	Debug.Log("Stand Alone OSX");
    #endif

    #if UNITY_STANDALONE_WIN
      Debug.Log("Stand Alone Windows");
    #endif

  }			   
}

Boo Example:

import UnityEngine

class PlatformDefines (MonoBehaviour): 

	def Start ():
		ifdef UNITY_EDITOR:
			Debug.Log("Unity Editor")

		ifdef UNITY_IPHONE:
			Debug.Log("IPhone")

		ifdef UNITY_STANDALONE_OSX:
			Debug.Log("Stand Alone OSX")

		ifdef not UNITY_IPHONE:
			Debug.Log("not an iPhone")

Then, depending on which platform you selected, one of the messages will get printed on the Unity console when you press play.

In addition to the basic #if compiler directive, you can also use a multiway test in C# and JavaScript:-

#if UNITY_EDITOR
    Debug.Log("Unity Editor");
#elif UNITY_IPHONE
    Debug.Log("Unity iPhone");
#else
    Debug.Log("Any other platform");
#endif

However, Boo currently supports only the ifdef directive.

Custom Preprocessor Directives

It is also possible to define your own preprocessor directives to control which code gets included when compiling. To do this you must add in the "Assets/" folder a text file with the extra directives. The name of the file depends on the language you are using :

C#	<Project Path>/Assets/smcs.rsp
C# - Editor Scripts	<Project Path>/Assets/gmcs.rsp
UnityScript	<Project Path>/Assets/us.rsp
Boo	<Project Path>/Assets/boo.rsp

As an example, if you include the single line '-define:UNITY_DEBUG' in your smcs.rsp file the define UNITY_DEBUG will exist as a global define for C# scripts, except for Editor scripts.

Every time you make make changes to the .rsp files a recompilation needs to be done for them to be effective. You can do this by updating or reimporting a single script (.js, .cs or .boo) file.

The usage of the .rsp files is described in the help of the smcs application, included in the Editor installation folder. You can get more information by running : "smcs -help".

Page last updated: 2012-05-30