科技版本課件PPT

1、Adam SchaefferMicrosoft CorporationSESSION CODE: WPH308Consistent sets of hardware capabilities defined by MicrosoftResolutionTouch InputCPU / GPURAMHardware keyboard is optionalLow level controlStraight to the metalRaw performance tuningHigh level abstractionRely on compiler and runtimeDeveloper pr

2、oductivityPowerful and expressiveType safety reduces hard-to-track-down bugsReflectionInitializer syntaxGreat tooling (IntelliSense)Similar enough to C that learning and porting are easyBlazingly fast compilesC#Usually within a few percent of native performanceAwesome generational garbage collection

3、Performance shootout: Raymond Chen vs. Rico Marianihttp:/ delta between managed and native.NET Compact FrameworkSimplistic mark-and-sweep garbage collectionXbox is not a general purpose computerUnforgiving in-order CPU architectureRequires custom VMX instructions for optimal math perfSecurity archit

4、ecture poses challenges for jitted codeIn between Windows and Xbox 360.NET Compact FrameworkKeep an eye on garbage collection!ARMv7 CPUMore forgiving toward jitted codeARM jitter is more mature than PPCInstance methodInterfaceDelegate / eventReflectionVirtual methodC+ allows independent choice of.NE

5、T types dictate their allocation and usage semanticsData typeThe memory in which a type lives (placement new)How a type instance is referenced (T, T*, T&, const T&)Value typesint, bool, struct, Vector3Reference typesclass, array, string, delegate, boxed value typesOft-repeated wisdomValue ty

6、pes live on the stackReference types live on the heapValue types live wherever they are declaredReference types have two piecesMemory allocated from the heapA pointer to this heap memoryThat is subtly incorrectBy default, prefer class over structureUse struct for things that areSmall (= 16 bytes)Sho

7、rt livedPass large structures by referenceMatrix a, b, c;c = Matrix.Multiply(a, b); / copies 192 bytes!Matrix.Multiply(ref a, ref b, out c);C+.NETAllocateInitially fast, becoming slower as fragmentation increasesVery fast, apart from periodic garbage collectionsFreeFastInstantaneousFragmentationIncr

8、eases over timeNoneCache coherencyRequires custom allocatorsThings allocated close in time are also close in physical locationGarbage collection is not optionalCant have type safety without automatic memory managementTriggered per megabyte of allocation1Starts with root references (stack variables,

9、statics)2Recursively follows all references to see what other objects can be reached3Anything we didnt reach must be garbage4Compacts the heap, sliding live objects down to fill holes5Frameworks designed for performanceFrameworks designed for performanceMake it run Less OftenIf you never allocate, G

10、C will never runMake it Finish QuicklyCollection time is proportional to how many object references must be traversedUse object poolsSimple heap = fast collectionUse value types and integer handlesExplicitly forces a garbage collectionUse wisely to give yourself more headroomAfter loadingDuring paus

11、es in gameplayDont call every frame!Beware of boxingstring vs. StringBuilderUse WeakReference to track GC frequencyhttp:/ CLR Profiler on WindowsSee MIX10 talk: “Development and Debugging Tools for Windows Phone 7 Series”Use .NET Reflector to peek behind the curtainhttp:/www.red- hardware accelerate

12、d 2D sprite drawingBasicEffectSkinnedEffectEnvironmentMapEffectAlphaTestEffectDualTextureEffect0-3 directional lightsBlinn-Phong shadingOptional textureOptional fogOptional vertex colorBasicEffectVertex CostPixel CostNo lighting51One vertex light401Three vertex lights601Three pixel lights1850+ Textu

13、re+1+2+ Fog+4+2DualTextureEffectFor lightmaps, detail textures, decalsBlends two texturesSeparate texture coordinatesModulate 2X combine mode (A*B*2)Good visuals at low pixel costVertex CostPixel CostTwo Textures76+ Fog+4+2For billboards and impostersAdds alpha test operations (pixel kill)Standard b

14、lending is free with all effectsOnly need alpha test if you want to disable depth/stencil writesAlphaTestEffectVertex CostPixel Cost, =, 66=, !=610+ Fog+4+2SkinnedEffectFor animated models and instancingGame code animates bones on CPUVertex skinning performed by GPUUp to 72 bonesOne, two, or four we

15、ights per vertexVertex CostPixel CostOne vertex light554Three vertex lights754Three pixel lights3351+ Two bones+7+0+ Four bones+13+0+ Fog+0+2EnvironmentMapEffectOooh, shiny!Diffuse texture + cube environment mapCheap way to fake many complex lightsFresnel term simulates behavior when light reaches a

16、 surface and some reflects, some penetratesVertex CostPixel CostOne light326Three lights366+ Fresnel+7+0+ Specular+0+2+ Fog+0+2FramerateNumberof PixelsPixel CostFramerate 30 hz refresh rate No point updating faster than the display! Game.TargetElapsedTime = TimeSpan.FromSeconds(1f / 30);Pixel Cost P

17、refer cheaper effects Minimize overdrawMany known algorithms:Distance, frustum, BSP, sort front to backImplement “overdraw x-ray mode” Draw untextured with additive blendingBrighter areas indicate overdrawNumberof Pixels 800 x480 is 25% more pixels than Xbox 1Great for textToo many pixels for intens

18、ive games800 x480 = 384,000 pixels600 x360 = 216,000 pixels (56%) Dedicated hardware scaler Does not consume any GPU Higher quality than bilinear upsamplingAvoidPreferRenderTargetUsage.PreserveContentsRenderTargetUsage.DiscardContentsdevice.BlendState = new BlendState .;/ At startupstatic BlendState myState = new BlendState .;/ Per frameDevice.BlendState = myState;VertexBuffer.SetData(.)device.DrawUserPrimitives(.);/ orDynamicVertexBuffer.SetData(., SetDataOptions.NoOverwrite);Great