Deep dive: Tips & tricks for porting games from other platforms to Windows 8Randy SpongField EngineerUnity Technologies

The GoalUnderstand the work needed to bring your existing Unity project over to Microsoft’s Windows Store for Windows 8 and Windows RT devices

The GoalUnderstand the work needed to bring your existing Unity project over to Microsoft’s Windows Store for Windows 8 and Windows RT devicesKnowing the unique features & behaviors of Windows 8/RT and Unity for Windows Store Apps, you’ll be better prepared to estimate the amount of work required to port your project

The GoalUnderstand the work needed to bring your existing Unity project over to Microsoft’s Windows Store for Windows 8 and Windows RT devicesKnowing the unique features & behaviors of Windows 8/RT and Unity for Windows Store Apps, you’ll be better prepared to estimate the amount of work required to port your projectYour knowledge of the changes to the runtime APIs for Windows Store Apps will make your porting work go more quickly

The GoalUnderstand the work needed to bring your existing Unity project over to Microsoft’s Windows Store for Windows 8 and Windows RT devicesKnowing the unique features & behaviors of Windows 8/RT and Unity for Windows Store Apps, you’ll be better prepared to estimate the amount of work required to port your projectYour knowledge of the changes to the runtime APIs for Windows Store Apps will make your porting work go more quicklyYour understanding of performance hotspots and optimization techniques will help you extract maximum performance from Windows 8 and Windows RT devices

The GoalUnderstand the work needed to bring your existing Unity project over to Microsoft’s Windows Store for Windows 8 and Windows RT devicesKnowing the unique features & behaviors of Windows 8/RT and Unity for Windows Store Apps, you’ll be better prepared to estimate the amount of work required to port your projectYour knowledge of the changes to the runtime APIs for Windows Store Apps will make your porting work go more quicklyYour understanding of performance hotspots and optimization techniques will help you extract maximum performance from Windows 8 and Windows RT devices

AgendaOverview of Windows 8 and Windows RTOverview of Unity’s Windows Store add-onPorting Existing CodeOptimizing PerformanceBest Practices for porting your Unity project

Windows 8 and Windows RT

Hardware Landscape

(Slide provided courtesy of Microsoft, 2012)

New Category of Windows PCs New design point

Always on, always connected System on a chip Battery is primary power source Focus on low power

Both x86/x64 and ARM-based systems Covers a range of form factors

(Slide provided courtesy of Microsoft, 2012)

Range of Performance

NVIDIA GeForce 650 NVIDIA GeForce 650M NVIDIA Tegra 3 Qualcomm Adreno 2250

100

200

300

400

500

600

700

800

900

GPU Performance Comparison

GigaFLOPS

Windows 8/RT Device Capabilities Windows 8 & RT devices scale in performance from

phone-equivalent all the way to high-end multi-GPU gaming desktop

Touch is a first-class citizen Minimum device resolution is 1366x768 Windows RT has a minimum DirectX feature level of

9_1 May not have 4k texture support May not have simultaneous render targets

Unity for Windows Store

Differences Unity’s Windows Store runtime is built on .NET Unity apps for Windows Store can only consume WinRT Components (no unmanaged DLLS)

Many new Windows devices have a trackpad and touchscreen that can be used simultaneously

Other Things to Watch Out For No 64-bit Windows Store Apps just yet Boo, JavaScript not fully implemented Network classes not supported (WWW is fully implemented, though)

Cloth not supported Microphone not implemented

Other Things to Watch Out For, Continued

Animation of script variables is not allowed AnimationEvent callback functions with arguments

(Supported: a function with no arguments or with AnimationEvent argument)

GameObject.SendMessage - The function argument types the message receiver must exactly match the message (we don’t have type conversion)

No fog for devices with DX feature level less than 9.3 Example workaround at http://files.unity3d.com/tomas/Metro/Examples/MyCustomFog.shader

Things to Get Excited About C# debugging in Visual Studio Building the Unity project generates a tweakable Visual Studio project Simplifies native code plugin integration

Your ported code pretty much ‘just works’ on Windows Phone 8

Porting Existing Code

Overview Disallowed Windows APIs Sharing plugin code between the Editor and your Windows Store App

Disallowed Windows APIs HashTable ArrayList System.Xml.XmlDocument System.Threading.Thread And a few thousand Win32 functions

Disallowed Windows APIsHashTable

Use a Dictionary Better performance for value types Not necessarily thread-safe Type-constrained

Disallowed Windows APIsArrayList

Use a Dictionary or a List<T> Possibly a small loss of performance

Disallowed Windows APIsSystem.Xml.XmlDocument

Don’t use XML But if you have to… use System.Xml.Linq Better is to use JSON or YAML

Disallowed Windows APIsSystem.Threading.Thread

Use ThreadPoolshttp://msdn.microsoft.com/en-us/library/windows/apps/windows.system.threading.threadpool

Disallowed Windows APIsWin32 APIs

Winsock2, CreateThread, HeapCreate, Sleep, etc.

(SuspendThread, GetThreadContext, SetUnhandledExceptionFilter are the ones that really threw us for a loop)

Find Windows 8/RT -compatible alternatives at http://msdn.microsoft.com/en-us/library/windows/apps/hh464945.aspx

Plugins in Windows Store AppsWindows Store Apps can only consume WinRT Components Unmanaged legacy native code DLLs aren’t allowed

Check out the details athttp://msdn.microsoft.com/en-us/library/windows/apps/hh441569.aspx

The Unity Editor is still based on Mono Make sure your WinRT Component can also be built as a legacy

native code DLL (Windows Store functionality can be stubbed out)

Optimizing Performance

Component CachingInterop in Unity for Windows Store Apps is expensive

Minimize the Unity APIs you call each frame, including Component references

Component CachingBad

public class example : MonoBehaviour { void Update() { transform.Translate(0, 0, 5); }}

Component CachingGood

public class example : MonoBehaviour { private Transform myTransform;

void Awake() { myTransform = transform; } void Update() { myTransform.Translate(0, 0, 5); }}

Component CachingTerrible

public class example : MonoBehaviour { void Update() { for (int i = 0; i < 1000; ++i) { transform.Translate(0, 0, transform.position.z + 0.005f); } }}

GameObject PoolingInstantiating and Destroying GameObjects is expensive Reuse when possible!

GameObject PoolingInstantiating and Destroying GameObjects is expensive Reuse when possible!

Instead of Destroying:gameObject.SetActive(false);MyPoolManager.AddToFreePool(gameObject);

Instead of Instantiating:GameObject gameObject = MyPoolManager.GetFreeObject();SetupObjectDefaults(gameObject);gameObject.SetActive(true);

Draw Calls - Dynamic Batching Works automatically Maximum of 900 vertex attributes per mesh Differently scaled objects won’t batch together Dynamic Batching incurs some CPU overhead at runtime

Draw Calls - Static Batching Supports arbitrarily complex geometry Can significantly reduce CPU usage at runtime for setting up draw

calls

Objects cannot move, rotate, or scale Objects must be marked as static in Unity Uses lots of device memory

Draw Calls - Texture Atlasing Batching only works when objects share materials

Combine object textures into a Texture Atlas

Draw Calls - Texture Atlasing

Draw Calls - Texture Atlasing

Unity Features on Windows RTDon’t Use Desktop shaders Terrains Realtime shadows Dense particles Non-tessellated sprites

Sprite Meshes

(Images provided courtesy of Bento Studio [Uni2D], 2013)

Use Our Documentation

Use Our DocumentationThe Unity documentation is full of concise and useful optimization advicePractical Guide to Optimization for MobilesOptimizing Graphics PerformanceMobile Developer Checklist – Optimizations

Best Practices

Animated Loading Screen Camouflages your loading times Gives the user a sense of progress

Target Device Testing Regularly use different devices for development testing Including the crappy ones

Stay Compliant Run the WACK tool regularly

Aim for daily runs when you’re refactoring for Windows 8 support or laying down new .NET code

Recap

Recap - Windows 8 and Windows RT Windows 8 and RT are mobile operating systems

Touch is a first-class citizen Broad range of form factors Broad range of performance capabilities

Recap – Unity for Windows Store Need to handle both trackpad and mouse input in the same app

Native code plugins have to be rewritten as WinRT Components

The Editor can’t consume WinRT Components (need to use a version of the com

Recap – Porting Existing Code Convert usage of HashTable and ArrayList to Dictionary

Rewrite native code plugins as WinRT Components Keep a native code version (which stubs Windows Store

functionality) for using in the Editor’s Play Mode

Recap – Optimizing Performance Cache Component references Pool GameObjects Batch draw calls Use texture atlases to increase batch sizes Avoid expensive “do it all” features like terrain Use Unity’s extensive optimization resources

http://docs.unity3d.com/Documentation/Manual/MobileOptimisation.html http://docs.unity3d.com/Documentation/Manual/iphone-PracticalGuide.html http://docs.unity3d.com/Documentation/Manual/OptimizingGraphicsPerformance.html

Recap – Best Practices Test on low-end devices more than high-end devices

Run the WACK toolkit regularly Finds coding errors and use of disallowed APIs Informs you about potential certification failures

Resources for Windows 8 & RTDisallowed .NET APIshttp://msdn.microsoft.com/en-us/library/windows/apps/xaml/br230302.aspx

Allowed win32 APIshttp://msdn.microsoft.com/en-us/library/windows/apps/br205757.aspx

Replacing disallowed win32 APIshttp://msdn.microsoft.com/en-us/library/windows/apps/hh464945.aspx

Windows 8 & RT Hardware Compatibility FAQhttp://www.microsoft.com/en-us/windows/compatibility/win8/compatcenter/faq

Resources for UnityWindows 8 and Windows RT Open Beta Sign-Uphttp://unity3d.com/beta/windowsstoreapps

Windows 8/RT Help In the Editor: “Help -> Unity Manual (Metro)”

Mobile Optimization Tipshttp://docs.unity3d.com/Documentation/Manual/MobileOptimisation.html

Optimizing Graphics Performancehttp://docs.unity3d.com/Documentation/Manual/OptimizingGraphicsPerformance.html

Practical Guide to Optimization for Mobileshttp://docs.unity3d.com/Documentation/Manual/iphone-PracticalGuide.html