【Unite 2017 Tokyo】Unity最適化講座 ~スペシャリストが教えるメモリとCPU使用率の負担最小化テクニック~

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May 08, 17

スライド概要

講演者:イアン・ダンドア(Unity Technologies)

こんな人におすすめ
・メモリ使用を削減したいプログラマー、開発者全般

受講者が得られる知見
・メモリ、GPU、CPUのリソースの無駄使いを発見し、削減するテクニック

講演動画:https://youtu.be/jHpkoJAMDGE

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リアルタイム3Dコンテンツを制作・運用するための世界的にリードするプラットフォームである「Unity」の日本国内における販売、サポート、コミュニティ活動、研究開発、教育支援を行っています。ゲーム開発者からアーティスト、建築家、自動車デザイナー、映画製作者など、さまざまなクリエイターがUnityを使い想像力を発揮しています。

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Ian Dundore Lead Developer Relations Engineer, Unity

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Optimizing Unity Saving CPU & Memory, because you can.

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What’ll we cover today? • • • • Primary focus will be CPU optimization. Transform component Animator Physics • Finish with some tips for saving memory.

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Always, always profile!

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Transforms! Not as simple as they look.

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Transforms? • Every GameObject has one. • When they change, they send out messages. • C++: “OnTransformChanged” • When reparented, they send out MORE messages! • C#: “OnBeforeTransformParentChanged” • C#: “OnTransformParentChanged” • Used by many internal Unity Components. • Physics, Renderers, UnityUI…

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OnTransformChanged? • Sent every time a Transform changes. • Three ways to cause these messages: • Changing position, rotation or scale in C# • Moved by Animators • Moved by Physics • 1 change = 1 message!

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Why is this expensive? • Message is sent to all Components on Transform & all Children • Yes, ALL. • Physics components will update the Physics scene. • Renderers will recalculate their bounding boxes. • Particle systems will update their bounding boxes.

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void Update() { transform.position += new Vector3(1f, 1f, 1f); transform.rotation += Quaternion.Euler(45f, 45f, 45f); }

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X void Update() { transform.position += new Vector3(1f, 1f, 1f); transform.rotation += Quaternion.Euler(45f, 45f, 45f); }

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void Update() { transform.SetPositionAndRotation( transform.position + new Vector3(1f, 1f, 1f), transform.rotation + Quaternion.Euler(45f, 45f, 45f) ); }

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Collect your transform updates! • Many systems moving a Transform around? • Add up all the changes, apply them once. • If changing both position & rotation, use SetPositionAndRotation • New API, added in 5.6 • Eliminates duplicate messages

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What system has lots of moving Transforms?

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100 Unity-chans! • Over 15,000 Transforms! • How will it perform?

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Performance Test (Unity 5.6) times in ms iPad Air 2 Macbook Pro, 2017 Unoptimized 33.35 6.06 Optimized 26.96 3.37 Timings are only from Animators

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“Optimized”?

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What does it do? • Reorders animation data for better multithreading. • Eliminates extra transforms in the model’s Transform hierarchy. • Need some, but not all? Add them to the “Extra Transforms” list! • Allows Mesh Skinning to be multithreaded.

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“Optimized”?

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Physics!

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What affects the cost of Physics? • Two major operations that cost time: • Physics simulation • Updating Rigidbodies • Physics queries • Raycast, SphereCast, etc.

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Scene complexity is important! • All physics costs are affected by the complexity and density of a scene. • The type of Colliders used has a big impact on cost. • Box colliders & sphere colliders are cheapest • Mesh colliders are very expensive • Simple setup: Create some number of colliders, cast rays.

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Cost of 1000 Raycasts times in ms 10 Colliders 100 Colliders 1000 Colliders Sphere 0.27 0.48 1.53 Box 0.34 0.42 1.67 Mesh 0.37 0.53 2.27 Objects created in a 25-meter sphere

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Density is important! times in ms 10 meters 25 meters 50 meters 100 meters Sphere 2.13 1.28 1.08 0.78 1000 Raycasts through 1000 Spheres

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Why is complexity important? • Physics queries occur in three steps. • 1: Gather list of potential collisions, based on world-space. • 2: Cull list of potential collisions, based on layers. • 3: Test each potential collision to find actual collisions.

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Why is complexity important? • Physics queries occur in three steps. • 1: Gather list of potential collisions, based on world-space. • Done by PhysX (“broad phase”) • 2: Cull list of potential collisions, based on layers. • Done by Unity • 3: Test each potential collision to find actual collisions. • Done by PhysX (“midphase” & “narrow phase”) • Most expensive step

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Reduce number of potential collisions! • PhysX has an internal world-space partitioning system. • Divides world into smaller regions, which track contents. • Longer rays may require querying more regions in the world. • Benefit of limiting ray length depends on scene density! • Use maxDistance parameter of Raycast! • Limits the world-space involved in a query. • Physics.Raycast(myRay, 10f);

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Control maxDistance! times in ms 10 meters 25 meters 50 meters 100 meters 1 meter 1.85 1.02 0.49 0.50 10 meters 2.10 1.19 0.91 0.53 100 meters 2.11 1.36 1.07 0.77 Infinite 2.13 1.28 1.08 0.78 1000 Raycasts through 1000 Spheres

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Edit the physics layers! • Consider making special layers for special types of entities in your game • Help the system cull unwanted results.

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Trade accuracy for performance • Reduce the physics time-step. • Running at 30FPS? Don’t run physics at 50FPS! • Reduces accuracy of collisions, so test changes carefully. • Most games can accept timesteps of 0.04 or 0.08

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[RequireComponent(typeof(Rigidbody))] class MyMonoBehaviour : MonoBehaviour { void Update() { transform.SetPositionAndRotation(…); } }

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X [RequireComponent(typeof(Rigidbody))] class MyMonoBehaviour : MonoBehaviour { void Update() { transform.SetPositionAndRotation(…); } }

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[beta]
[RequireComponent(typeof(Rigidbody))]
class MyMonoBehaviour : MonoBehaviour
{
Rigidbody rb;
void Awake()
{
rb = GetComponent<Rigidbody>();
}
void Update()
{
rb.MovePosition(…);
rb.MoveRotation(…);
}
}

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Common errors: Rigidbody movement • Do not move GameObjects with Rigidbodies via their Transform • Use Rigidbody.MovePosition, Rigidbody.MoveRotation 500 objects MovePosition & MoveRotation Transform SetPositionAndRotation FixedUpdate 0.45 0.90

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Memory time!

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IL2CPP Platforms: Memory Profiler • Available on Bitbucket • https://bitbucket.org/Unity-Technologies/memoryprofiler • Requires IL2CPP to get accurate information. • Shows all UnityEngine.Objects and C# objects in memory. • Includes native allocations, such as the shadowmap

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Examining a memory snapshot

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Examining a memory snapshot

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Examining a memory snapshot ?!

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Examining a memory snapshot

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This is a shadowmap… do we need one?

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Look at the HideFlags

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HideAndDontSave? • Value in the HideFlags enum. • Includes 3 values: • HideInHierarchy • DontSave • DontUnloadUnusedAsset • Mistake: Setting in-game assets to use this HideFlag. • Assets loaded with HideAndDontSave flag will never be unloaded!

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Examining a memory snapshot

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Examining a memory snapshot

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Examining a memory snapshot

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Check your assets! • Common for artists to add assets in very high resolutions. • Does Unity-chan’s hair really need three 1024x1024 textures? • Reduce size? Achieve the same effect some other way?

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Beware of Asset Duplication • Common problem when placing Assets into Asset Bundles • Assets in Resources & an Asset Bundle will be included in both • Will be seen as separate Assets in Unity • Separate copies will be loaded into memory • Also happens when Asset Dependencies are not declared properly

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Asset Dependencies Material A Shader A Material B Texture (shared) Shader B

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Asset Dependencies Material A Shader A Material B Texture (shared) Shader B

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Asset Dependencies Material A Shader A Material B Texture (shared) Shader B

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Asset Dependencies Material A Shader A Material B Texture (shared) Texture (shared) Shader B

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Asset Dependencies Material A Shader A Material B Texture (shared) Shader B

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Runtime texture creation • Creating textures procedurally, or downloading via the web? • Make sure your textures are non-readable! • Read-write textures use twice as much memory! • Use UnityWebRequest — defaults to non-readable textures • Use WWW.textureNonReadable instead of WWW.texture

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Marking textures non-readable • Pass nonReadable as true when calling Texture2D.LoadImage • Texture2D.LoadImage(“/path/to/image”, true); • Call Texture2D.Apply when updates are done • Texture2D.Apply(true, true); • Updates mipmaps & marks as non-readable • Texture2D.Apply(false, true); • Does not update mipmaps, but does mark as non-readable

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Thank you!