UE4 Pak打包、挂载、加载

首先，必须得明确的一点就是如果想要加载Pak内资源，那么这些资源必须是经过Cook的。如果打包的是未Cook的资源，那么即使Pak挂载成功，也不可能会成功加载Pak内资源。

不知道怎么生成Cook资源，可以看我前一篇 ​​​​​​UE4 Cook指定平台资源_来梦学长i的博客-CSDN博客

打包Pak

首先，将引擎目录下"Engine\Binaries\Win64"添加到系统环境变量中

方式一：使用命令行方式打包

打包Pak的命令行格式

UnrealPak “存储Pak的路径+Pak包名” -create="Cook好的资源的路径"

打开CMD键入打包命令，执行打包Pak

示例一：打包整个Content文件

UnrealPak "E:\ProjectName\Pak\ContentPak.pak" -create="E:\ProjectName\Saved\Cooked\Content"

示例二：打包单个指定文件

UnrealPak "E:\ProjectName\Pak\SiglePak.pak" -create="E:\ProjectName\Saved\Cooked\Content\FileName\FileName.uasset"

方式二：使用批处理方式打包

@ECHO OFF
ECHO ---------------------------------------------------------------
ECHO		UnrealPak Strart Create Pak
ECHO ---------------------------------------------------------------set PakFilename="E:\AndroidVR\Pak\ContentPak.pak"
set CookedFileName="E:\AndroidVR\Saved\Cooked\Newfile"
set UnrealPak="E:\UE4.26\Engine\Binaries\Win64\UnrealPak.exe"
CALL %UnrealPak% %PakFilename%  -create=%CookedFileName%ECHO ---------------------------------------------------------------
ECHO		UnrealPak Finished
ECHO ---------------------------------------------------------------
PAUSE

  打包完成，即可在你自己指定的目录下找到打包好的Pak文件

挂载Pak

如果手动将Pak放在以下这些项目路径中，引擎将会自动加载Pak

• [ProjectName]/Content/Paks
• [ProjectName]/Saved/Paks
• Engine/Content/Paks

也可以使用以下方法，手动挂载Pak

挂载Pak的功能需要C++代码实现，项目Build.cs中加入"PakFile"模块

包含必要头文件

#include "HAL/PlatformFilemanager.h"
#include "IPlatformFilePak.h"

创建函数，用于获取平台文件

FPakPlatformFile* FSimpleHotPakModule::GetPakPlatformFile()
{if (!PakPlatformFile){if (IPlatformFile* InPlatformFile = FPlatformFileManager::Get().FindPlatformFile(TEXT("PakFile"))){PakPlatformFile = static_cast<FPakPlatformFile*>(InPlatformFile);}else{PakPlatformFile = new FPakPlatformFile();if (PakPlatformFile->Initialize(&FPlatformFileManager::Get().GetPlatformFile(), TEXT(""))){FPlatformFileManager::Get().SetPlatformFile(*PakPlatformFile);}}}return PakPlatformFile;
}

创建函数，用于判断是否已经挂载指定Pak，防止重复挂载

@PakFilename       Pak包名bool USimpleHotPakBPLibrary::IsMounted(const FString& PakFilename)
{if (FPakPlatformFile* InPakFile = GetPakPlatformFile()){TArray<FString> PakFilenames;//获取已经挂载的Pak数组容器InPakFile->GetMountedPakFilenames(PakFilenames);//判断其中是否已经包含Pakreturn PakFilenames.Contains(PakFilename);}return false;
}

 创建函数，用于挂载Pak

@PakFilename       Pak包名
@PakOrder          Pak加载优先级
@MountPoint        Pak挂载到哪个路径bool AHotUpdateTestCharacter::MountPak(const FString& PakFilename, int32 PakOrder, const FString& MountPoint)
{if (FPakPlatformFile *InPakFile = GetPakPlatformFile()){if (!IsMounted(PakFilename)){//返回挂载结果return InPakFile->Mount(*PakFilename, PakOrder, *MountPoint);}}return false;
}

创建函数，用于卸载Pak

@PakFilename       Pak包名bool AHotUpdateTestCharacter::UnmountPak(const FString& PakFilename)
{if (FPakPlatformFile* InPakFile = GetPakPlatformFile()){return InPakFile->Unmount(*PakFilename);}return false;
}

方法都准备好了，开始挂载Pak

值得说明的是，MountPoint路径是你所打包的Cook资源的相对路径

例如打包了一个"ProjectName/Saved/Cooked/Content/Asseset"路径下的资源，那么这个资源的挂载点则是"ProjectName/Content/Asseset"

//Pak文件路径
FString PakFileName = FPaths::ProjectDir() / TEXT("Pak/Asset.pak");
//Pak挂载点
FString PakMountPoint = FPaths::ProjectContentDir() / TEXT("Asset/");if(MountPak(*PakFileName,3,*PakMountPoint))
{}

这样就已经将Pak挂载到引擎中了，接下来则是加载Pak中的资源

资源加载

动态加载资源

//Pak文件路径
FString PakFileName = FPaths::ProjectDir() / TEXT("Pak/Asset.pak");
//Pak挂载点
FString PakMountPoint = FPaths::ProjectContentDir() / TEXT("Asset/");if(MountPak(*PakFileName,3,*PakMountPoint))
{FString AssetPath = "'Blueprint'/Gmae/Asseset/AssetName.AssetName_C'";if(AActor *TheActor = Cast<AActor>(StaticLoadObject(UObject::StaticClass(),nullptr,*AssetPath))){GetWorld()->SpawnActor(TheActor,FVector(),FRotator());}
}

异步加载资源

//Pak文件路径FString PakFileName = FPaths::ProjectDir() / TEXT("Pak/Asset.pak");//Pak挂载点FString PakMountPoint = FPaths::ProjectContentDir() / TEXT("Asset/");if(MountPak(*PakFileName,3,*PakMountPoint)){if (FPakPlatformFile*InPakPlatformFile = GetPakPlatformFile()){FPakFile*InPakFile = new FPakFile(InPakPlatformFile,*PakFileName,false);TArray<FSoftObjectPath> AllReourcePath;TArray<FString> Files;InPakFile->FindFilesAtPath(Files,*InPakFile->GetMountPoint(),true,false,true);for (auto &InPak : Files){AllReourcePath.AddUnique(InPak);}UAssetManager::GetStreamableManager().RequestAsyncLoad(AllReourcePath,FStreamableDelegate::CreateLambda([&](){FString FileName = "'Blueprint'/Gmae/Asseset/AssesetName.AssesetName'";AActor*TheActor = FindObject<AActor>(nullptr,*FileName);}));}}