Using The New Flash Stage3D Web Technology To Build Your Own Next 3D Browser MMOG

1. Using The New Flash Stage3D Web Technology To Build Your Own Next 3D Browser MMOG Daosheng Mu, Lead Programmer Eric Chang, CTO XPEC Entertainment Inc.
2. Outline • Brief of Speakers • Introduction of Adobe Flash Stage3D API • XPEC Flash 3D Engine • Optimization for Flash Program • Future Works • Conclusion • Q & A
3. Brief of Speakers • Eric Chang – 19 Years of Game Industry Experiences – Cross-platform 3D Game Engine Development – PC/Console/Web
4. Brief of Speakers • Daosheng Mu – 4.5 Years of Cross-platform 3D Game Engine Development Experiences – PC/Console/Web
5. Why Flash? Native C/C++ vs. Unity vs. Flash Native C/C++ Unity Flash Development Difficulty High Low Mid Ease of Cross Platform Low High High Performance High Mid Low Market Popularity Low Mid High (>95%)
6. Project C4 Demo Video
7. Introduction of Adobe Flash Stage3D API
8. Stage3D • Support all browsers
9. Stage3D • Stage3D includes with GPU-accelerated 3D APIs – Z-buffering – Stencil/Color buffer – Vertex shaders – Fragment shaders – Cube textures – More…
10. Stage3D • Pros: – GPU accelerated API – Relies on DirectX, OpenGL, OpenGL ES – Programmable pipeline • Cons: – No support of alpha test – No support of high-precision texture format
11. Stage3D ResourceNumber allowedTotal memory Vertex buffers 4096 256 MB Index buffers 4096 128 MB Programs 4096 16 MB Textures 4096 128 MB* Cube textures 4096 256 MB Draw call limits 32,768 *350 MB is absolute limit for textures, 340 MB is the result we gather
12. AGAL • Adobe Graphics Assembly Language – No support of ‘if-else’ statements – No support of ‘constants’
13. XPEC Flash 3D Engine
14. Model Pipeline • Action Message Format (AMF): – Native ByteArray compression – Native object serialization 3DS Max Engine Loader Exporter Collada Binary Converter AMF AMF Engine Render
15. XPEC Flash 3D Engine • Application: update/render on CPU • Command buffer: store graphics API instruction Application Command buffer Driver GPU CPU
16. XPEC Flash 3D Engine: Application Object3D • Material • Geometry Update • UpdateDeltaTime • UpdateTransform Scene management • Scene partition • Frustum culling Update • UpdateHierarchy Draw • SetMaterial • SetGeometry Stage3D • Set Stage3D APIs
17. Scene Management • Goal: Minimize draw calls as possible • Indoor Scene – BSP tree • Outdoor Scene – Octree/Quad tree – Cell – Grid
18. Scene Management: Project C4 • Grid partition • Object3D: (MinX, MaxX), (MinY, MaxY) (0, 0) (2, 2) (4, 4) y x
19. Scene Management: Project C4 • Frustum: (MinX, MaxX), (MinY, MaxY) (0, 0) (2, 2) (4, 4) (1,4),(0,4) y x
20. XPEC Flash 3D Engine: Command Buffer Initialize • createVertex/Index Buffer • createTexture • createProgram Begin • clear • setRenderToTexture Draw • setVertex/Index Buffer • setProgram • setProgramConstants • setRenderState • setTextureAt • drawTriangles End • present • Avoid user/kernel mode transition • Decrease shader patching – “Material sorting” • Reduce draw call – “Shared buffers” – “Dynamic batching”
21. Material Sorting • Opaque/Translucent
22. Material Sorting • State management • 1047/2598 draw calls
23. 0 10 20 30 40 50 60 NVIDIA 8800GT - 1047 draw calls NVIDIA 8800GT - 1047 draw calls with material sorting NVIDIA 8800GT - 2598 draw calls NVIDIA 8800GT - 2598 draw calls with material sorting Elapsedtime(ms) CPU waiting GPU Render loop
24. 0 10 20 30 40 50 60 70 80 90 100 NVIDIA 6600GT - 1047 draw calls NVIDIA 6600GT - 1047 draw calls with material sorting NVIDIA 6600GT - 2598 draw calls NVIDIA 6600GT - 2598 draw calls with material sorting Elapsedtime(ms) CPU waiting GPU Render loop
25. Before sorting(ms) After sorting(ms) NVIDIA 8800 GT - 1047 draw calls Render loop elapsed time 16 16 Total elapsed time 41 40 NVIDIA 8800 GT - 2598 draw calls Render loop elapsed time 36 36 Total elapsed time 50 50 Before sorting(ms) After sorting(ms) NVIDIA 6600 GT - 1047 draw calls Render loop elapsed time 34 31 Total elapsed time 53 48 NVIDIA 6600 GT - 2598 draw calls Render loop elapsed time 81 64 Total elapsed time 89 89
26. Shared Buffers • Problem: – Numbers of buffers are limited ResourceNumber allowedTotal memory Vertex buffers 4096 256 MB Index buffers 4096 128 MB Programs 4096 16 MB
27. Shared Buffers Vertex Buffer Index Buffer Vertex Buffer Index Buffer Vertex Buffer Index Buffer
28. Particle System • Each particle property is computed on the CPU at each frame – Alpha, Color, LinearForce, Size, Speed, UV – Facing
29. Particle System • Index buffer – Indices will not be changed • Vertex buffer – Problem: • Particle amount depends on frame • Upload data to vertex buffer frequently
30. Particle System Static Index Buffer Dynamic Vertex Buffer Vertex Data
31. Skinned Model • Problem: – Lesser vertex constants allowed • 128 constants per vertex program – Global vertex constants • Lighting, Fog, Const
32. Skinned Model • 4x3 Matrix • Bone count per geometry is limited to 29 – “Split mesh” 128 constants / 3 = 42.6666 bones 3 * 29 bones = 87 constants
33. Shadow Map
34. Shadow Map present() End frame setRenderToBackBuffer() Set shadow map setRenderToTexture() Clear shadow map Draw to shadow map clear() Clear back buffer
35. Shadow Map • Problem: – Texture format: RGBA8 – Artifact • Aliasing • Popping while moving
36. • Size: 1024x1024 • RGBA8  R32 Shadow Map
37. Shadow Map • Percentage Closer Filtering (PCF) solution: – Hard shadow – Aliasing – Popping while moving
38. Shadow Map • PCF pw = 1/mapWidth ph = 1/mapHeight • Result = 0.5 * texel( 0, 0) + 0.125 * texel( -pw, +ph) + 0.125 * texel(-pw, -ph) + 0.125 * texel( +pw, +ph) + 0.125 * texel(+pw, -ph) (-pw , +ph) (+pw , +ph) (0, 0) (+pw , -ph)(-pw , -ph)
39. Shadow Map • PCF based solution: 0 20 40 60 80 100 NVIDIA 6600GT - 1047 draw calls NVIDIA 6600GT - 1047 draw calls with PCF NVIDIA 8800GT - 1047 draw calls NVIDIA 8800GT - 1047 draw calls with PCF Elapsedtime(ms) CPU waiting GPU Render loop
40. Toon Shading • Single pass – Problem: Dependent on no. of face • Two passes – Scale vertex position following the vertex normal – Not dependent on no. of face 𝑣 ∶ 𝑣𝑖𝑒𝑤 𝑣𝑒𝑐𝑡𝑜𝑟 𝜃 𝑖𝑓 𝜃 > 𝑡ℎ𝑟𝑒𝑠ℎ𝑜𝑙𝑑, 𝑑𝑟𝑎𝑤 𝑡𝑜𝑜𝑛 𝑐𝑜𝑙𝑜𝑟 𝑁 : 𝑣𝑒𝑟𝑡𝑒𝑥 𝑛𝑜𝑟𝑚𝑎𝑙
41. Toon Shading • Enable back face • Scale vertex position • Draw color Toon • Enable front face • Draw material General Result
42. Alpha Test • Problem: – Stage3D without alpha test – “kil opcode in AGAL” • Performance penalty on mobile device
43. Alpha Test • Solution: Render loop time(ms) Total time(ms) 6600GT alpha test 17~19 47 6600GT alpha blend 18~19 65~67 8800GT alpha test 0.16 37 8800GT alpha blend 0.3 36 •304 draw calls •Alpha-test performance is better on desktop Replace alpha-test with alpha-blend
44. Post Effect OriginGlowDOFColor Filter
45. Static Lightmap • Pros: – Pre-computation – Global illumination • Cons: – More textures
46. Optimization for Flash Program
47. Optimization for Flash Program • Problem: – For Each is slow • “Use for-loop to replace it” – Memory management • “Recycle manager” • “Strengthen garbage collection”
48. Optimization for Flash Program • Solution: – Recycle manager • Reduce garbage collection loading • Save objects initial time • public function recycleObject3D( obj:IObject3D ):void • public function requestObject3D( classType:int , searchKey:*, renderHandle:int = 0 ):*
49. Optimization for Flash Program • Solution: – Strengthen garbage collection • Avoid inner function • Force to dereference function pointer • Dereference attribute in object destructor
50. • Avoid inner function • Force to dereference function pointer Without inner function Use inner function
51. Optimization for Flash Program • Experiment: before vs. after – Switching among levels Before improvement: After improvement :
52. Rapid loading
53. Rapid loading • Streaming – Data compression • PNG: swf compression: 20%~55% • Package: zip compression: 25~30% – Batch loading • Separate resource to several packages • Download what you really need
54. Rapid loading Enter to avatar stage Enter to game stage After loading picture finished 5Mb/s Elapsed time (sec) 15 6 12 • game code • ui • game scene • scene textures
55. Future Works • Adobe Texture Format (ATF) – Support for compressed/mipmap textures on the different GPU chipset • FlasCC – C++  AS3 Compilation • AS3 Workers – Multi-thread support • MovieClip – Replace with Stage3D UI framework, ex: Starling
56. Conclusion • Cross-Device/Cross-OS/Cross-Browser – Browser + Cloud Computing – Write Once, Run Anywhere • Flash vs. HTML5 • Cross-Compiling Technology Trend – C/C++ + Flash/ActionScript – C/C++ + HTML5/JavaScript
57. Acknowledgements • XPEC - Project C4 Team • XPEC - RDO Team
58. Q & A Ellison_Mu@xpec.com Eric_Chang@xpec.com

Editor's Notes

2011.2 release
Based on flash player benefit: 市佔高、用戶多、商業行為市場大
3D API: 並且跨平台( browsers, mobile devices )，叫做stage3D。一個Flash Player最多可以使用到4個stage3D，所以可以做同時四個視窗的應用。

One codebase 跨所有的瀏覽器。所有使用flash player開發的應用都可以橫跨所有瀏覽器，並且效能差距也不大。
如果現在要用Html5 WebGL來做遊戲最常被討論的就是在哪個瀏覽器上效能差距如何，因為它是被不同瀏覽器所來處理
而Flash的所有程式都是在一個flash player內被執行，因此在 stage3D上作3D遊戲效能並不會差距很大。

Stage3d 提供了一般3d api該要有的功能:

Alpha test: 不支援一般desktop 3d api理應提供的render state，需要我們在pixel shader額外加上指令
RGBA: 對於高精確度的圖檔格式並沒有提供，每個channel只能存入8bit資料。我們在開發shadow map時，必須要特殊儲存方式的貼圖來存放深度資訊。

最大公約數texture 128 MB for mobile device，PC大約是340 MB。
MMOG仍然不夠用

Assembly -> ByteArray -> Program3D
不能使用branching, if…, 常數一定要透過shader constant傳入，不能直接在shader內被宣告
Pixelbender3D is readable and high-level, but AGAL is a good way to have good performance

以上是stage3D的介紹
接下來我想要分享我們如何使用Stage3D來打造一個適合Web MMORPG引擎的經驗

一個遊戲引擎都會需要適合自己的binary format。AMF: AMF是Adobe獨家開發出来的通信協議，主要用於Flash/Server溝通
可以使用原生的壓縮方式。
使用原生的序列化讀取，資料讀入方便。

如何做出一個效能好的3d engine要了解CPU-driver-GPU
CPU會將3d api的指令傳給command buffer，當時機到了之後就會交給driver指派給GPU來做處理
我們可以努力的部分就是CPU的部分。

UpdateTransform: world transform
UpdateHierarchy: 更新角色骨架、或是particle的property
Scene management: 正常的選擇方法~~~ex: bsp, cell…

Mode transition: User mode – 不能存取hardware相關資源
Kernel mode – 可以透過driver存取hardware資源

如何使用這些stage3D APIs:
Initialize做的事不要在update的時候做Update執行的command越少越好 ---

這裡有五個model，三種不同material
1: 會要切換五次material。
2: 排序過後，只需要切換三次material，command buffer所存放的指令變少了，也就可以減少mode transition帶來的penalty

8800GT 效能上無明顯差距
CPU: Core2Duo E4500 2.2G

6600GT
CPU: Pentium4 3.0G
1047 draw calls
- CPU api call花費了許多時間
- GPU 處理也影響到最後的總時間
2598 draw calls
- CPU api call的時間差距更明顯
- 總時間沒有差距，整體上GPU已經到達瓶頸

雖然material sorting在6600GT才有明顯效能提升，但我們的引擎是提供給Web game的專案使用
Web game的進入門檻較低，此優化方法能讓低階硬體玩家，享受到優化後的效能提升。

MMOG的人物、配件數目很多容易遭遇到限制上限

Can put same model share the same buffer
可以減少buffer創建的份數

Facing to screen, facing up, facing to parent, facing view up未來應該要實作GPU particle，目前在CPU方面計算特效非常吃重

一條vertex buffer，在particle要被生成的時候再被加入這條buffer。
好處: 節省buffer數目，如果material是一樣的甚至可以一起發出draw call
隱憂: Stage3D並沒有一個flag可以指定這條buffer想用動態屬性，他們現在一律都是靜態屬性，修改buffer內容會比較傷害效能，好在我們一個frame只會做一次。

由於vertex constant不多，我們又固定幾條是用來當做全域設定，
Bone matrix 4x4

所以我們能給bone matrix使用的剩下不多考慮一個draw call…增加draw call 拆mesh

將深度的計算結果評分配到各個channel

PCF (percentage-closure filter)

Put on different with PCF and non-pcf
Vexel.depth result > shadowMapResult color is black
Vexel.depth result < shadowMapResult color is white

選shadow map的原因: 地形高低起伏，正確的深度投影、自投影可以視情況關閉

整體效能並沒有影響

Game is comic style
Two pass效能差
選two pass原因: 因為我們面數過低

選two pass原因: 因為我們面數過低

It can be removed, one mobile use alpha blend to replace
我們曾經為了將我們的demo放到iPad上，fps 從1x~2x，就是把所有用到alpha test的 material改成alpha blend

Alpha blend在desktop其實影響比較嚴重。

以下還有一些我們引擎擁有的效果，今天沒有時間一一細講

省去realtime光影的計算

Memory leak: 由於一些物件被認為是有reference到，造成GC機制不會去回收它，但我們其實認為他理應要被回收，所以造成記憶體被堆疊
Memory leak: inner function, dereference, recycle
For loop use for loop to replace for each

Memory leak: inner function, dereference, recycle
For loop use for loop to replace for each

GC不如開發者所想的理想化在適當的地方都要被正確回收
Inner function: 記憶體累積快速，並且GC的啟動很頻繁

一個不停創建含有 inner function物件的實驗，回收就自動交由flash vm的GC來處理

說明釋放跟載入

Web game最重要的部分就是能夠快速進入場景
資料量小
下載量少

第一次進入遊戲，cache清空狀態

以上，就是今天所分享的關於Stage3D製作web 3d MMOG engine心得，未來仍有許多需要加強優化的項目。

PNG: memory usage is large, no-size compression, mipmap
Alchemy: 70% native code performance
Starling 可以取代movieclip提供完整3d加速

Using The New Flash Stage3D Web Technology To Build Your Own Next 3D Browser MMOG

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Using The New Flash Stage3D Web Technology To Build Your Own Next 3D Browser MMOG

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