Unity和UE4开发VR的优劣

#/7轻量级，安装、调试和打包方便配置VR项目十分简单学习成本低，文档完善开发成本低UI系统在PS4上调试方便，有批处理文件可以一键运行AssetStore提供了一些VR下的Demo作为参考Unity的劣势：内建工具不够完善渲染差，光照系统糟糕，阴影bake有bug，只能勉强达到2A游戏入门水平对于控制器支持较差，一些如手柄震动、VR控制器空间定位的功能引擎未集成，需要第三方插件或额外代码没有材质编辑器，需要第三方插件Prefab不支持继承没有xx的LevelStream支持Unreal的优势：画面效果完全达到3A游戏水准光照和物理渲染即便在缩水的状况下也足以秒杀Unityxx系统，从此策划不用再写代码强大的材质编辑器各种官方插件xx对于手柄、VR控制器支持良好提供各种游戏模版，用来做原型配合Blueprint甚至比Unity更快Unreal的劣势：C++如果要开发PS4游戏需要重新编译引擎，12核服务器，24线程编译大概需要20-30分钟如果需要重新编译引擎，光拉代码就需要至少一个小时创建新项目大概又要编译十多分钟如果切换平台，要编译几千到上万个shaderPS4部署不方便，打包编译同样非常久学习成本高，各子模块功能强大但操作复杂部分功能没有任何文档，已有功能的文档同样不够完善，不如Unity开发成本高，某国内3A团队做了个10分钟的VRDemo，据说已经烧了一千多万UI设计器非常之难用VR下的一些bestpractice同样缺乏文档和例子，目前都在摸石头过河Buuuuuuuuuuug我觉得写了这么多结论已经很明显了：小团队没钱追求快速出效果，对画面要求不高的项目用Unity。中大团队不差钱，买得起Unreal技术支持，分工明确有专人填坑，对画面要求高的项目用Unreal。这里还有一篇老外写的关于Unity和Unreal的文章，建议阅读：ExtroForgeTheSwitchfromUnity3DtoUnrealEngineAHighLevelDecisionLetmestartoffbysayingthatI(andotherteammembers)arestillHUGEfansofUnity.SeveralofusontheteamhavebeenusingUnitysincev3.Xdays(includingProlicenses)andCONTINUEtouseitforvariousprojects.IfIwasstartingamobileprojecttoday,IwouldstillreachforUnity.WemadeaLOTofprogressonprotypingExtroForgewiththeUnityengine.Hugeswathsofgameplayelementswereengineeredandintegrated.WethrivedwiththerichvarietyofAssetStorepackagesavailabletousaswellastheYEARSofonlineposts,blogsandtutorials.Withatleasttwo15-yearsoftwareengineeringprofessionalsontheteam,wewereefficientandproficientunderUnity.image08Thefirstiterationwaslessthanimpressive.Extremelylimited(missing?)documentationandoddball(buggy?flaky?)performance.Simplereplicationofananimatedmodel(location/rotation)waseithernon-functionalorsuper-laggy.Weexperimented.Wereadforumposts.Wewaited.TherewerenoofficialUnitytutorials.SomeofthepeoplethatWEREmakingtutorialvideosthatwefollowedactuallygaveupanddecidedtowaituntilfuturereleases.ThentheUnityroadmapwaspublished.WiththeimplementationofthestandalonesimulationserverpushedouttoMarchof2016(plussomeotherelementsundefined),wedecidedtolookatotheroptions.WhatapleasantshockitwastofireupUnrealforthefirsttimewithastarterprojectandseethatlittlesidemenunexttothe“Play”buttonthatallowedyoutoauto-startnotjustadedicatedserver,butalsoasmany‘additional'playerclientsasyouwantedto.Itwasmultiplayernirvana.NotethatthiswasnotSOLELYadecisionbasedonmultiplayerfunctionalitybuiltintotheengine.Wehavestruggledforsometimetogettheworld/terrain/foliage/watertolookthewaywewanted.OurTeam/Studioleadwhowasresponsibleforthelookandfeeldecidedtolookatsomeothergameenginestoseehowquicklyhecouldachievethedesiredresults(ourUnityresultseitherlookedtoocartoonishortoo“claylike”).image09C#versusC++versusBlueprints...ohmy.Yeah-notsomuch.image02Oneseniorteammemberhadalreadystartedwiringupsomeblueprintfunctionality-addingtotheskeletonfirstpersoncharacterBPthatwastiedtotheC++classesIhadbeenworkingon.Creatinglittleboxes.dragginglittlewires..allthecolors!!!Iwasfascinated.Mostofitwasinput/controlsrelatedaswellasGUI/UIstuff-elementsIfiguredwereprobablythebestuseforBlueprints.IstartedmyforayintoblueprintsmyselfwasforMateriallogic.IwasAMAZEDatthestuffwecouldeasilydoinsecondsinamaterialblueprintthatwouldhavetaken..DAYSwritingshadercodeinUnity.Itwaseasy,itwasfast,anditwas(dareIsayit)satisfyinglyFUN.WhilemycoderemainedfirmlyinC++land,weslowlylearnedtoexposevariablesfromtheC++sidesotheycouldbeaccessedfromtheseinput/UIblueprintsasneed(stillhaven'tdeterminedifyoucanaccessaBPvariable/functionfromC++side-butitlookslikeitispainful).IlearnedthatIcouldcreatemycriticalsettingsandinitializearraysofimportantgameelementsinC++(whereitwassafeinanon-binary-corruptiblefile)andexposeitintobeusedasnecessaryinBlueprints.Sortof.Sointerestinglyenough..enumsarenowthebaneofmyexistence.Iloveenums.BeenahugefansincebeforethedawnoftimeandhaveusedthemineveryhighlevellanguagesinceIwasaweeengineer.AssetManagementUnityassetmanagementisaverymaturebeast.Dragafileintotheeditor,copyafiletotheAssetsfolder-itjustworked.Moveassetsaroundtodifferentdirectories-justdraganddrop.Thepackageimport/exportfunctionality(someflakydeterminationofdependenciesaside)wastopnotch.Therewereevenenginefunctionsexposed(througheditorscripts)thatallowedyoutocodeallsortsofneato-whizbangcustomlogictomanageyourimage05resources.OurexperienceswithUnreal,howeverweresomewhatpainful.Someofthiswasduetoignorance/inexperienceonourpart-butsomeisstillamystery.Tryingtomigratecontentfromoneprojecttoanother-withdifferentdirectorystructuresprovidedmanywastedhours.Tryingtomigrate(usingthetoolsUnrealprovided)BlueprintsbasedonC++classeswasanunmitigateddisaster.C++classescan'tbemigrated-youhavetocopyonyourown-butshouldyouneedtochangeclassnames(wemigratedfromaprojectwherethewewantedtorenametheautogeneratedcharactercontrollerclasses)themigratedblueprintsarepermanentlycrippleddotoun-changeablereferencestotheoriginalclass.Movingcontent(in-editor)betweenfolderswasalsoaseverepainpoint-Unrealwouldexplicitlyleavecopiesoffilesbehindoremptysubfoldersandallsortsofreferenceswouldgetbroken(someun-fixable).Wegotburnedsomuchbythatlastissue,wesimplytryNOTtomovecontentaround-beingextremelycarefulwhereweplaceitemsfromtheverybeginning.Tobefair,Unity'scritical‘assetdatabase'COULDgetcorruptedandwhenitdid,youwereinforaloongperiodofre-importingalltheassets.ButUnitydidthisallautomatically(detectingitsowncorruptionandfixingitself)-whereasanydetectionofissuesorfixingisdonemanuallyinUnreal.AsfarastheUnityAssetStoreversustheUnrealMarketplaceisconcerned-it'ssimplyamatterofmaturity.Unityhashadyearstobuildupalargeandthrivingstorefilledwithbothfree/inexpensiveandpricyassets(ofvaryingquality).AsanauthorofseveralUnitystoreassets,Iwashappywiththecontentcreationandsellingprocess(andmostimportantlypayout).FindingandimportingnewcontentinUnitywasfairlypainless.TheUnrealmarketplaceismostassuredlysmallerMuchsmaller.Tinyeven.Andthe‘average'priceforcontentishigher.Nodoubtaboutit.We'vehadnoexperienceyetwithselling(orevenbuying)assetsonthestore,usinginternallycreatedassetsorstartercontentasnecessary.ProceduralmeshmanipulationUnityprovidedtheabilitytomanipulatemeshdata(creatingfromscratchormanipulatingafterthefact)outofthebox.Vertices,vertexcolors,Uvs-itwasallaccessibleandwelldocumented.Overtheyears,Iuseditforcountlessreasons-terraindeformation,meshdestruction/fracturing,andinExtroForge,ourvoxelconstructionenginerequiredit.Itworkedwell,itwasfastanditwasubiquitous.LightingUnrealaddsanincrediblenumberofopenworldlightingtoolstoourarsenal.Yes,UnityrolledoutwithrealtimeglobalilluminationviatheEnlightenengine,butit'sstilllimitedforanopenworldwherestructuresarebeingaddedandremovedallthetime.Whatwereallybenefitedfromwasthedistancefieldambientocclusion,andtherealtimeindirectlightingvialightpropagationvolumes.Lookingintothedistance,thingsinUnitytendedtolookflat.Adistantmountainshouldcastashadowonthevalleybelow,butwithUnitywejustcouldn'tachievethatwithoutaninsaneshadowdistance.HighresScreenshot00218UnrealEnginehadasolutionforthatthat.Distancefieldshadowsandambientocclusionaredesignedtoshadefarawaythingsinanapproximatedkindofwaythatlooksperfectfromfaraway.Wereallywereabletogetthelushandwell-lit/wellshadedworldthatwewantedtowithUnrealEngine.Withlightpropagationvolumes,wewereabletocreateitemswithemissivematerialsthatwouldcastlightontonearbygeometry.Theresultinglookisfantastic.Again-thisislistedas‘experimental'(wehadtomakeasettingintheenginepropertyfilestoenableit),butsofar-sogood!OpenWorldToolsHighresScreenshot00280MiscellaneousFeaturesAndFunctionsOnefinalthing...image07IhavebeenonthereceivingendofseveralcriticalbugsinUnitythatpreventedsomemo