Unreal Engine4 学习笔记

坐标系

• unreal: x 前，y 右, z 上

编程入门

• https://docs.unrealengine.com/en-US/Programming/QuickStart/index.html
• https://docs.unrealengine.com/en-US/Programming/Introduction/index.html
• https://unrealcpp.com/line-trace-on-tick
• https://forums.unrealengine.com/community/community-content-tools-and-tutorials/101-victor-s-use-system-tutorial?43-Victor-s-Use-System-Tutorial=

Visual Studio Code

用 code 替换 vc 效果不错

• https://easycomplex-tech.com/blog/Usage-UE4-VScode/
• 在 code 中安装以下插件：C/C++, UnrealEngine 4 Snippets, vscode-epics
• 使用 Visual Studio Installer 安装 Visual C++ build tools 和 .Net Core build tools
• 修改 ue4 的设置： Editor Preferences - General - Source Code - Source Code Editor: Visual Studio Code
• 重启 unreal editor，File 菜单中选择 Generate / Refresh Visual Studio Code Project
• 编译时，在 vscode 中按 ctrl+shift+b，选择 win64 development editor build
• 修改 .vscode/c_cpp_properties.json，添加 "${workspaceFolder}/Intermediate/Build/Win64/UE4Editor/Inc/[project]" 到 includePath

Qt creator

没有尝试

• https://docs.unrealengine.com/zh-CN/Platforms/Linux/BeginnerLinuxDeveloper/SettingUpQtCreator/index.html?
• https://www.ue4community.wiki/legacy/qtcreator-in-windows-jc6qs4pv

文档

• https://docs.unrealengine.com/en-US/API/Runtime/Engine/GameFramework/AActor/index.html
• https://blog.csdn.net/yangxuan0261/article/details/52078303 TArray and TMap
• https://docs.unrealengine.com/zh-CN/Gameplay/HowTo/UsingCameras/SwitchingCameras/index.html 场景中多个摄像机的切换
• https://forums.unrealengine.com/development-discussion/c-gameplay-programming/1638743-reading-anim-curve-float-values-at-all-time
• https://docs.unrealengine.com/en-US/Engine/Rendering/Materials/HowTo/RadialMotionBlur/index.html
• https://docs.unrealengine.com/en-US/API/Runtime/Engine/Components/USceneComponent/index.html
• https://docs.unrealengine.com/en-US/API/Runtime/Core/Math/FVector/index.html
• https://docs.unrealengine.com/en-US/API/Runtime/Core/Math/FRotator/index.html
• https://docs.unrealengine.com/en-US/API/Runtime/Core/Math/FQuat/index.html

父子层级

meshComponent->SetUpAttachment(rootComponent) 将一个组件绑定在另一个组件下面

获取所有组件

	TArray<UStaticMeshComponent*> comps;
	GetComponents< UStaticMeshComponent>(comps);	//包含根组件

debug

UE_LOG(LogTemp, Warning, TEXT("count comps: %d"), comps.Num());
UE_LOG(LogTemp, Warning, TEXT("comp: %s"), *c->GetName());	// FString

获取组件（物体）的变换

• GetActorLocation, GetComponentLocation, GetComponentTransform 返回世界坐标
• GetRelativeLocation, GetRelativeTransform 返回相对坐标
• SetRelativeLocation, SetRelativeRotation 设置相对变换
• AddActorLocalOffset, AddActorLocalRotation 增加本地空间的位移和旋转
• AddActorWorldOffset, AddActorWorldRotation 增加世界空间的位移与旋转

自定义类

• 没有任何继承的类不会出现在编辑器的内容浏览器中，虽然可以正常编译和运行，但会有一大推错误提示，也不出现书写提示
• 这种类可以修改为继承 UObject，不再使用 new xx 来创建实例，而是改用 NewObject<xx>()来创建，不需要手动 delete
• "xx.generated.h" 头文件必须是最后一个 include

添加类之后出现一堆错误

1. Go to a VS solution folder. Delete following folders : ".vs", "Intermediate", "Saved"
2. Delete solution (*.sln file). Keep *.uproject
3. Right click on *.uproject in explorer, click "switch unreal engine versoin" and select your current engine version. Project files and solutions will get regenerated.
4. Open your vs solution. Your generated files will be missing, so hit "build" button.
5. Go to Tools->Options->Text editor->Advanced, set "Recreate Database" to "true" and restart visual studio
6. Wait and pray for it to work (worked for me tho)

导入 fbx

blender 导出fbx时设置：Apply Scalings: All Local, Forward: X Forward, Up: Z Up 导入选项中勾选 Transform Vertex to Absolute，不要勾选：Convert Scene 可以自动调整模型单位

debug

• debug 显示找不到 ue4.exe，需要在项目管理中，在 games 项下的项目名上右击，选择 Set as startup project

物理

• AddImpulse 执行后，不会改变 GetPhysicsLinearVelocity 值。
• https://github.com/EpicGames/UnrealEngine/blob/release/Engine/Source/Runtime/Engine/Private/PrimitiveComponentPhysics.cpp
• https://github.com/EpicGames/UnrealEngine/blob/release/Engine/Source/Runtime/Engine/Private/PhysicsEngine/BodyInstance.cpp
• https://github.com/EpicGames/UnrealEngine/blob/release/Engine/Source/Runtime/Engine/Private/PhysicsEngine/PhysicsInterfacePhysX.cpp
• https://github.com/NVIDIAGameWorks/PhysX/blob/4050bbfdc2699dfab7edbf0393df8ff96bbe06c5/physx/source/physxextensions/src/ExtRigidBodyExt.cpp

physX

• https://github.com/NVIDIAGameWorks/PhysX/tree/ae80dede0546d652040ae6260a810e53e20a06fa/physx/source/physxvehicle/src

TickGroup

• https://blog.csdn.net/qq_37712328/article/details/106674150
• Actor默认tickgroup为TG_PrePhysics，所以在tick中AddImpulse是正常的，组件的tickgroup默认未知，物理会出现抖动。

场景切换

• Open Level 节点 + Level Name
• 延时节点 Delay
• Remove from Parent 节点可以将当前 ui 移除

动画

• Play Animation 节点控制动画播放

ui

• https://www.bilibili.com/video/BV12x41117bR?p=4
• https://zhuanlan.zhihu.com/p/135962214

修改图片属性

1. 在内容管理器中选择所有图片，右击 - Assets Actions - Bulk Edit via Property Matrix
2. Compression - Compression Settings: UserInterface2D
3. LevelOfDetail - Texture Group: UI
4. File菜单 - Save All

添加 ui 到场景

1. 打开 level blueprint
2. Event Begin Play - Create Widget 选择创建好的 ui 蓝图
3. 从 return value 拖出连线，选择 promote to variable，将新产生的 set 节点中的变量更名
4. 从 set 节点后引出 Add to Viewport 节点添加到视图 （需要移除时使用 Remove from parent 节点）

暂停游戏

Set game paused 节点

获取玩家实例

在 ui 类或其它类中可以通过 GetPlayerPawn 节点获取玩家 pawn，再添加 CastTo<MyPawnClass> 的节点转换成自己的 pawn类

组件的变换更新

• ComponentToWorld 世界空间变换，每帧更新这个在 USceneComponent::UpdateComponentToWorldWithParent 中
• AttachChildren 子组件
• GetComponentLocation, GetComponentTransform 组件的世界变换
• bComponentToWorldUpdated

技巧

• 在 .uproject 文件上点右键，菜单中有生成 .sln 工程文件的选项

禁止启动UE4的时候启动 steamvr

修改这个文件 Program Files\Epic Games\XXXX\Engine\Plugins\Runtime\Steam\SteamVR\SteamVR.uplugin 将 "EnabledByDefault" : true, 该为 "EnabledByDefault" : false,

禁止工程中的SteamVR

菜单中 编辑->插件 找到Vertual Reality中的SteamVR,禁止它

Use Aggressive Member List for Auto... True

读取目录中所有文件

UFUNCTION(BlueprintCallable) FString ReadFile(FString filename); 

FString UTextReaderComponent::ReadFile(FString filename)
{
	//Read file ini [project]/Content/Data/ 
        //you can change with other location
	FString directory = FPaths::Combine(FPaths::GameContentDir(), TEXT"Data");
	FString result;
	IPlatformFile& file = FPlatformFileManager::Get().GetPlatformFile();
	if (file.CreateDirectory(*directory)) {
		FString myFile = directory + "/" + filename;
		FFileHelper::LoadFileToString(result, *myFile);
	}
	return result;
}