Unite11 – Exporting to Flash from Unity

Last week, four of the Mind Candy tech team ventured over to San Francisco for the Unite conference. One of the things I was most keen to learn about is the upcoming Flash export.

On the Tuesday, we attended the Flash afternoon where Lucas Meijer and Ralph Hauwert detailed the latest progress on Unity’s export to Flash. On first impressions, the games they’ve been working on look fantastic! One of the reasons I’ve been keen on working with Unity over Flash for 3D games dev is the awesome toolset, and these guys have really nailed the Flash export.

As long as your code isn’t doing anything too “exotic”, Unity will convert your code (c#, js (strict) and boo) to ActionScript. It will then compile this, along with your assets, into a swf using the mxmlc compiler. One thing to note here is that literally everything is compiled into that one swf. There was mention of them using asset bundles at a later date to generate individual swfs for content such as scenes. Since everything is in one swf, that means file sizes could get pretty large really quickly. One of the demo apps generating simple spheres compiled to a ~1.4mb (iirc) swf which is pretty chunky for something so simple.

The generated AS3 code is pretty readable although since there’s no method overloading in Flash, they’ve had to compromise on function names somewhat! That said, it should be pretty easy to debug your exported app.

The features currently supported in Flash are:

  • PhysX
  • Particle system
  • Custom and standard shaders

Things that won’t work in the first version include:

  • Anything needing depth textures
  • Advanced audio such as doppler and reverb
  • Dynamic shadows
  • Mouse lock
  • Unity networking (you’ll have to use a Flash networking solution for now)

Looking at the performance of the games, they seemed to run pretty well. They mentioned trying to push anything you can to the GPU rather than CPU. An example given would be to animate textures in a shader rather than scrolling it in a script, as well as the usual light baking and occlusion culling. Basically, as Lucas put it: “The best way to make your game go faster, is to have it not do stuff”.

So to summarise – from a first glance, the Flash export looks pretty awesome, and the Unity guys have done a great job getting it working. There are still a fair few features missing, but there should be enough there for most simple Unity games to be exported. Unfortunately, both the release date and the price were listed as “TBA”, so I guess you’ll have to wait a little longer before you can try it out.

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