Flash: Building & Running

The following is a step-by-step guide to build and run a new project exported to Flash.

Create your Unity content.
Choose File->Build Settings to bring up the Build Settings dialog and add your scene(s).
Change the Platform to Flash Player
Target Player can be left as the default. This option enables you to change the target Flash Player based on the features you require (see http://www.adobe.com/support/documentation/en/flashplayer/releasenotes.html for details).
Tick Development Build. (This causes Unity to not compress the final SWF file. Not compressing will make the build faster, and also, the SWF file will not have to be decompressed before being run in the Flash Player. Note that an empty scene built using the Development Build option will be around 16M in size, compared to around 2M compressed.)
The Strip Physics Code option can be selected if you do not need the PhysX engine. If checked, the build will not compile the PhysX engine into the final SWF, resulting in a smaller file.
Press the Build button.

Unity will build a SWF file at the location you choose. Additionally it will create the following files:

an html file - Use this to view your Flash-built content.
a swfobject.js file - Handles checking for the Flash Player and browser integration.
a UnityShared.swc file.

To view your Flash-built content open the html file. Do not open the SWF file directly.

Build-and-run will create the same files, launch your default browser and load the generated html file.

The UnityShared.swc file created in the build allows you to load the SWF in your own project. Embedding the Unity content in a standard flash project allows you to do GUI in Flash. This type of Flash integration will of course not work in any of the other build targets.

As with the other build targets, there are Player settings that you can specify. Most of the Flash settings are shared with other platforms. Note that the resolution for the content is taken from the Standalone player settings.

We allow for a Flash API that gives you texture handles, which in combination with the swc embedding will give you means to do webcam, video, vector graphics from flash as textures.

Texture Support

We support jpeg textures, as well as RGBA / Truecolor. The compression ratio can be specified in the texture import under 'Override for FlashPlayer' setting. Compressed textures get converted to jpeg with the chosen compression ratio. The compression ratio is worth experimenting with since it can considerably reduce the size of the final SWF.

Texture quality ranges from 0 to 100, with 100 indicating no compression, and 0 the highest amount of compression possible.

The maximum supported texture resolution is 2048x2048.

Build Errors and Warnings

The Build Process

The Unity Flash Publisher attempts to convert scripts from C#/UnityScript into ActionScript. In this process, there can be two kinds of conversion errors:

errors during conversion of unity code to ActionScript
errors while compiling the converted code.

Errors during conversion will point to the original files and will have the familiar UnityScript error messages with file names and line numbers.

Errors during the compilation of the converted ActionScript will take you to the message in the generated ActionScript code (with filenames ending with .as).

Debugging Converted ActionScript Code

During a build, the converted ActionScript (.as) files are stored within your project folder in:

/Temp/StagingArea/Data/ConvertedDotNetCode/

If you encounter errors with your SWF (at runtime or during a build), it can be useful to look at this converted code.

It is possible that any ActionScript errors at compilation time will not be easily understood. Just remember that the ActionScript is generated from your game script code, so any changes you need to make will be in your original code and not the converted ActionScript files.

Specific Errors and Warnings

1. What does this error message mean? "Failed assemblies stripper ... Unhandled Exception: Mono.Linker.ResolutionException: Can not resolve reference: System.String UnityEngine.WWW::get_text()"

This means that you have a precompiled dll in your project that was not built with flash support in mind and references classes that Unity Flash does not support.

2. Why do I get:

'TerrainCollider' is not supported when building for FlashPlayer.
'TerrainData' is not supported when building for FlashPlayer.
Asset: 'Assets/New Terrain.asset'

The terrain feature is not supported when building for the FlashPlayer target. All un-supported features will generate a similar warning. Note that the build will continue, however, the unsupported feature will be missing from the final SWF.

3a. Why do I get: Error: Call to a possibly undefined method RuntimeServices_UnboxSingle_Object through a reference with static type Class.

This is likely because the conversion between types that is defined on the UnityScript side is not defined for our Flash Publisher. Any time you see an error that refers to Unbox it means a type conversion is required but cannot be found.

3b. What should I do about this?

Do not forget to use #pragma strict, and take care of all "implicit downcast" warning messages.

The rule of thumb is to avoid runtime casts from Object to primitive types (int, float, etc.). Also prefer containers with explicit types to generic ones, for example:

System.Collections.Generic.List.<float> instead of Array
Dictionary<string, float> instead of Hashtable

4. Why do I get Error building Player: UnauthorizedAccessException: Access to the path "Temp/StagingArea/Data/ConvertedDotNetCode/global" is denied.

If Unity-generated ActionScript files are open in a text editor, Unity may refuse to build issuing this error. To fix this, please close the ActionScript files and allow Unity to overwrite them.

Note: The Flash export feature is currently available as a developer preview. This feature is still in development and thus the above information is subject to change.

Page last updated: 2012-05-10