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Practical Guide for Optimizing Unity on Mobiles

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This is a presentation from GIC Poland 2015 conference on mobile optimization techniques.

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Practical Guide for Optimizing Unity on Mobiles

  1. 1. COPYRIGHT 2014 @ UNITY TECHNOLOGIES PRACTICAL GUIDE TO OPTIMIZATION ON MOBILES Valentin Simonov Field Engineer @ Unity Technologies E-mail: val@unity3d.com Skype: simonov.valentin Comment: additional comments were added to slides. Content shown in live demos is obviously missing.
  2. 2. COPYRIGHT 2014 @ UNITY TECHNOLOGIES Valentin Simonov Field Engineer @ Unity Technologies • Work with Unity customers to get maximum performance from their games • Teach Unity • Translated a book about Unity • Maintain a few open source projects: • https://github.com/TouchScript/TouchScript E-mail: val@unity3d.com Skype: simonov.valentin
  3. 3. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES OPTIMIZATION
  4. 4. COPYRIGHT 2014 @ UNITY TECHNOLOGIES while (true) { var stuff = FindStuffToOptimize(); if (stuff == null) break; Optimize(stuff); } Comment: in theory optimization loop is that simple. In practice we have such annoying concepts like TIME and MONEY, so FindStuffToOptimize() function must also consider impact and business value of issues it returns.
  5. 5. COPYRIGHT 2014 @ UNITY TECHNOLOGIES Stuff FindStuffToOptimize() { var stuff = …; // ??? return stuff; } Comment: so, how should the FindStuffToOptimize function work?
  6. 6. COPYRIGHT 2014 @ UNITY TECHNOLOGIES Every developer knows where issues in his code are.
  7. 7. COPYRIGHT 2014 @ UNITY TECHNOLOGIES Every developer knows where issues in his code are. Comment: LOL! Of course not. Developers usually know where the code they’d LIKE to optimize is, but without actual profiling it is impossible to say if this makes sense.
  8. 8. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES SET THE TARGET DEVICE
  9. 9. COPYRIGHT 2014 @ UNITY TECHNOLOGIES “How do I optimize my game on iOS?” Random Unity Developer Comment: All phones are very different. The first step must be figuring out what your target device is. The question “How do I optimize my game on iOS” doesn’t make sense, instead you should ask “How do I make my game run 30 fps on iPhone 4s?”.
  10. 10. COPYRIGHT 2014 @ UNITY TECHNOLOGIES TEST SCENE Chinese pool simulator Comment: next you need a reference scene to base your tests on. This scene must contain 1.5-2x all assets that is possible to create in your game. For example if you are making a pool simulator game, this is how your test scene should look.
  11. 11. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES TEST AND MEASURE
  12. 12. COPYRIGHT 2014 @ UNITY TECHNOLOGIES DON’T WASTE TIME! You must: 1. Know how to use tools to get data from the target device, 2. Have enough knowledge to interpret this data. Comment: this must be the most important slide. If you are not following this procedure you most likely just wasting time. This is probably one of the fundamental differences between senior and junior developers. When junior developers encounter an issue they run around in panic, while senior developers seem to know what they are doing.
  13. 13. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES 1. Set the target device 2. Test and measure 3. Know your platform 4. Know your tools 5. Profile on device 6. CPU 7. GPU 8. Memory 9. Project structure
  14. 14. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES KNOW YOUR PLATFORM
  15. 15. COPYRIGHT 2014 @ UNITY TECHNOLOGIES “Nothing is black and white…” * Except black and white. Comment: nothing is ever black and white. You should not blindly do (or not do) things because you were told that they were bad. Usually it depends…
  16. 16. COPYRIGHT 2014 @ UNITY TECHNOLOGIES “The trouble with quotes on the Internet is that you can never know if they are genuine.” Abraham Lincoln
  17. 17. COPYRIGHT 2014 @ UNITY TECHNOLOGIES DRAW CALLS ARE NOT THE WORST Comment: static batching in Unity is implemented with several draw calls with no state changes which are fast.
  18. 18. COPYRIGHT 2014 @ UNITY TECHNOLOGIES OVERDRAW IS YOUR ENEMY Comment: all mobile devices have a maximum number of pixels they can draw a second. Divided by 60 fps and retina resolution you’ll get a relatively low number. This means that you should really try to avoid drawing fully transparent pixels which get alpha blended.
  19. 19. COPYRIGHT 2014 @ UNITY TECHNOLOGIES Comment: to avoid overdraw you can use more complex geometry effectively cutting empty space.
  20. 20. COPYRIGHT 2014 @ UNITY TECHNOLOGIES Comment: when you import sprites Unity automatically does this for you. But it doesn’t do it very smart. There are plugins on Asset Store which do much better job.
  21. 21. COPYRIGHT 2014 @ UNITY TECHNOLOGIES DON’T USE CUTOUT SHADERS Comment: cutout shaders are bad on mobile GPUs. Here’s a test where I was rendering a fullscreen transparent checkerboard. Left: transparent shader, right: cutout shader.
  22. 22. COPYRIGHT 2014 @ UNITY TECHNOLOGIES DON’T MOVE 2D COLLIDERS • Box2D can’t change colliders, it has to recreate them • Don’t move 2d colliders • Only move transforms with Rigidbody2D
  23. 23. COPYRIGHT 2014 @ UNITY TECHNOLOGIES KNOW WHERE ASSETS LIVE • There’s native (c++) and managed (c#) memory • Assets live in native memory • Managed memory has light wrappers for assets • myTexture = null; — wrapper is GCd, texture data is stuck • Destroy(myTexture); — wrapper is stuck, texture data is freed • Resources.UnloadUnusedAssets(); — destroys stuck assets
  24. 24. COPYRIGHT 2014 @ UNITY TECHNOLOGIES EXAMPLE: WWW • WWW www = new WWW(…) -> allocate buffers • www.Dispose() -> release buffers • GC(?)-> www.~WWW() -> release buffers WWW wrapper WWW data Managed
  25. 25. COPYRIGHT 2014 @ UNITY TECHNOLOGIES READ THIS: • Unity iOS and Android - cross-platform challenges and solutions http://www.realtimerendering.com/downloads/MobileCrossPlatformChallenges_siggraph.pdf • Tuning your OpenGL ES app https://developer.apple.com/library/ios/documentation/3DDrawing/Conceptual/OpenGLES_Programming Guide/Performance/Performance.html • Squeezing performance out of your unity gear vr game https://developer.oculus.com/blog/squeezing-performance-out-of-your-unity-gear-vr-game/ https://developer.oculus.com/blog/squeezing-performance-out-of-your-unity-gear-vr-game-continued/ • Mobile performance tuning: poor man's tips and tricks http://www.slideshare.net/valentinsimonov/mobile-performance-tuning-48786822
  26. 26. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES KNOW YOUR TOOLS
  27. 27. COPYRIGHT 2014 @ UNITY TECHNOLOGIES KNOW YOUR TOOLS • Unity Profiler • Unity Frame Debugger • Xcode • Xcode Frame Debugger • Instruments Comment: here a sample game is shown and different tools are used to get relevant data while it’s running on an iPhone.
  28. 28. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES PROFILE ON DEVICE
  29. 29. COPYRIGHT 2014 @ UNITY TECHNOLOGIES PROFILE ON DEVICE • Hardware is very different • Editor uses a different player • Editor keeps more stuff in memory • It’s possible to do a lot of unnecessary work (GetComponent<T>() allocates???!)
  30. 30. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES CPU
  31. 31. COPYRIGHT 2014 @ UNITY TECHNOLOGIES CPU • Loading time: • Resources overhead • Parsing/loading JSON/XML • Building cached data • Downloading bundles • Instantiating stuff • Useless calculations: • Invisible objects • Empty cameras • Physics
  32. 32. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES GPU
  33. 33. COPYRIGHT 2014 @ UNITY TECHNOLOGIES GPU • Overdraw • Sprite geometry • Particle systems (super bad on iPhone4) • WTF geometry (wrong or totally useless) • Broken batching • Shader complexity
  34. 34. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES MEMORY
  35. 35. COPYRIGHT 2014 @ UNITY TECHNOLOGIES MEMORY • Garbage in managed memory -> GC lag spikes • instantiation • foreach allocates* 40 bytes • … all the other stuff • Resources in native memory
  36. 36. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES PROJECT
  37. 37. COPYRIGHT 2014 @ UNITY TECHNOLOGIES PROJECT • Multiple JSON/XML parsers • Multiple tween engines • Multiple loggers • Example code • All this stuff goes into generated IL2CPP code • Example: 72Mb vs. 64Mb generated code size on test game
  38. 38. COPYRIGHT 2014 @ UNITY TECHNOLOGIES STUFF WE FOUND • Loading time: • 2 seconds to parse JSON • 3 seconds to generate the list of images from the bundle • 2 seconds to fill pool of bots • WWW is not disposed • Resources overhead • Empty fullscreen quad • Broken batching, a lot of overdraw on sprites • 2D colliders are constantly rebuilt due to animation • Shaders are too complex • Text is constantly updated • Game Over window is very heavy • foreach loops allocate 40 bytes each • A lot of unnecessary code • …
  39. 39. COPYRIGHT 2014 @ UNITY TECHNOLOGIESCOPYRIGHT 2014 @ UNITY TECHNOLOGIES 1. Have you RTFM? 2. Do you know your target device? 3. Are you profiling on device? 4. Are you using the right tools? 5. Are you fixing the right issues? QUESTIONS?

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