Unreal Engine: Difference between revisions
(→C++) |
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= C++ = |
= C++ = |
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== Variable names == |
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If you want to use real variable names but have nice names in the UE editor too, then use meta/DisplayName |
If you want to use real variable names but have nice names in the UE editor too, then use meta/DisplayName |
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UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Camera, Meta = (DisplayName = "First Person Camera Component") ) |
UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Camera, Meta = (DisplayName = "First Person Camera Component") ) |
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UCameraComponent* m_pFirstPersonCameraComponent; |
UCameraComponent* m_pFirstPersonCameraComponent; |
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== owner / client /server == |
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The instance that spawned the class is always ROLE_Authority. If an Actor is spawned on the client, the client is the authority. |
The instance that spawned the class is always ROLE_Authority. If an Actor is spawned on the client, the client is the authority. |
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-- OmaManfred |
-- OmaManfred |
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</pre> |
</pre> |
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== Logging == |
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The following is just a copy/paste/change from the UE4 wiki and was really done from different persons, I am just using the work of different people here. |
The following is just a copy/paste/change from the UE4 wiki and was really done from different persons, I am just using the work of different people here. |
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</pre> |
</pre> |
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=== Example Usage === |
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#include "Log.h" |
#include "Log.h" |
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PLOG("I am telling you: %s", *sPssst); |
PLOG("I am telling you: %s", *sPssst); |
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=== Custom Log === |
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If you want your own selectable category in the log filter to be able to only show your log messages, then you have to |
If you want your own selectable category in the log filter to be able to only show your log messages, then you have to |
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* add this line in the Log.h above any defines: |
* add this line in the Log.h above any defines: |
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You will - in most cases - remove (nearly) all log messages when your code is running well. So... do this only if you need this, not because you think this is the "better" way to use it. |
You will - in most cases - remove (nearly) all log messages when your code is running well. So... do this only if you need this, not because you think this is the "better" way to use it. |
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== Am I client or server ? == |
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https://answers.unrealengine.com/questions/416305/how-to-know-if-listenserverclient-owner-for-rpc.html |
https://answers.unrealengine.com/questions/416305/how-to-know-if-listenserverclient-owner-for-rpc.html |
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</pre> |
</pre> |
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== UMG with C++ base class == |
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* create a normal UMG widget |
* create a normal UMG widget |
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* create a C++ class with base class UserWidget (UUserWidget) |
* create a C++ class with base class UserWidget (UUserWidget) |
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</pre> |
</pre> |
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== SLATE == |
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The "canvas" in UMG is "SConstraintCanvas" in Slate. |
The "canvas" in UMG is "SConstraintCanvas" in Slate. |
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== Multiplayer / Sessions == |
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Do not search for "multiplayer", search for "sessions". |
Do not search for "multiplayer", search for "sessions". |
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This is a Youtube video I found which gives you an overview, so you already have an idea how it works before you start learning the details: [https://www.youtube.com/watch?v=JOJP0CvpB8w Multiplayer in Unreal Engine: How to Understand Network Replication]. |
This is a Youtube video I found which gives you an overview, so you already have an idea how it works before you start learning the details: [https://www.youtube.com/watch?v=JOJP0CvpB8w Multiplayer in Unreal Engine: How to Understand Network Replication]. |
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== String conversions == |
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from: https://docs.unrealengine.com/en-us/Programming/UnrealArchitecture/StringHandling/FString |
from: https://docs.unrealengine.com/en-us/Programming/UnrealArchitecture/StringHandling/FString |
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FString TestHUDString = FString(TEXT("This is my test FString.")); |
FString TestHUDString = FString(TEXT("This is my test FString.")); |
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FText TestHUDText = FText::FromString(TestHUDString); |
FText TestHUDText = FText::FromString(TestHUDString); |
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== Classes == |
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* You can create and use normal C++, like, create a normal C++ class and use new and delete with it. |
* You can create and use normal C++, like, create a normal C++ class and use new and delete with it. |
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* But if you want to use UE stuff, you must use UE stuff and be sure to not mix it with normal C++ handling. This sounds complicated, but it is just a reminder to for example never use "new" for an actor. |
* But if you want to use UE stuff, you must use UE stuff and be sure to not mix it with normal C++ handling. This sounds complicated, but it is just a reminder to for example never use "new" for an actor. |
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** create them manually (I still have to modify the properties of the created .cpp files, not funny) |
** create them manually (I still have to modify the properties of the created .cpp files, not funny) |
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=== UE classes === |
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Please keep in mind that my information might be wrong. |
Please keep in mind that my information might be wrong. |
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About categories, there seem to be some ... reserved? ones. Whatever the reason, they don't work. I never got the category "Test" to show, there should be others. So, do not use "Test" as category if you have the same effect, just change the category name instead of trying to force it. |
About categories, there seem to be some ... reserved? ones. Whatever the reason, they don't work. I never got the category "Test" to show, there should be others. So, do not use "Test" as category if you have the same effect, just change the category name instead of trying to force it. |
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==== DLLEXPORT ==== |
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Your classes will be inside a DLL and have to be exported to be usable. If you use UE to create a class you will see something like this: |
Your classes will be inside a DLL and have to be exported to be usable. If you use UE to create a class you will see something like this: |
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class P01_TEST_API AMyFirstActor : public AActor |
class P01_TEST_API AMyFirstActor : public AActor |
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If you want to use the same header files but without "DLLEXPORT", then you just change the define. And that has - of course - to be done per project. So, yes, it does make sense. |
If you want to use the same header files but without "DLLEXPORT", then you just change the define. And that has - of course - to be done per project. So, yes, it does make sense. |
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==== minimum ==== |
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The minimum of a UE class would be like this: |
The minimum of a UE class would be like this: |
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===== header file ===== |
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<pre> |
<pre> |
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#pragma once |
#pragma once |
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</pre> |
</pre> |
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===== Source file ===== |
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<pre> |
<pre> |
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#include "MyFirstActor.h" |
#include "MyFirstActor.h" |
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</pre> |
</pre> |
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===== *.generated.h ===== |
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#include "MyFirstActor.generated.h" |
#include "MyFirstActor.generated.h" |
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Write it just like that, you don't create it, you don't look into it, you don't really care about it. BUT you have to include it as LAST include file in your header file. |
Write it just like that, you don't create it, you don't look into it, you don't really care about it. BUT you have to include it as LAST include file in your header file. |
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===== UCLASS() ===== |
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This has just to be there. For certain things to work you have to add words inside the brackets. |
This has just to be there. For certain things to work you have to add words inside the brackets. |
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An example would be: |
An example would be: |
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These words do what they say. You can use the class as a type in a blueprint or you can create a blueprint from this class. |
These words do what they say. You can use the class as a type in a blueprint or you can create a blueprint from this class. |
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===== GENERATED_BODY() ===== |
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The default for a struct is public and the default for a class is private. |
The default for a struct is public and the default for a class is private. |
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That means "GENERATED_BODY()" in this code |
That means "GENERATED_BODY()" in this code |
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Don't think, just put it before any access specifiers, it works. |
Don't think, just put it before any access specifiers, it works. |
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==== Variables and the like ==== |
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You might want certain functionality from UE for certain enums, member variables or methods. Like.. it should work as expected and not be cleared by the system which seems to be able to be happen to certain UE container classes if you don't make them UE properties. |
You might want certain functionality from UE for certain enums, member variables or methods. Like.. it should work as expected and not be cleared by the system which seems to be able to be happen to certain UE container classes if you don't make them UE properties. |
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* UPROPERTY(BlueprintReadWrite, EditAnywhere, Category = "Misc", Meta=(DisplayName="Cool Name")) |
* UPROPERTY(BlueprintReadWrite, EditAnywhere, Category = "Misc", Meta=(DisplayName="Cool Name")) |
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===== Enums ===== |
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UE enums must be outside of classes (since 4.12). This means you have to be creative with your naming or will slap yourself if you have two enum types which you called EStatus. (This might not even be possible now.) |
UE enums must be outside of classes (since 4.12). This means you have to be creative with your naming or will slap yourself if you have two enum types which you called EStatus. (This might not even be possible now.) |
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* DisplayName: The name which is used to show this data's label (instead of the variable name) |
* DisplayName: The name which is used to show this data's label (instead of the variable name) |
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===== Variables ===== |
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You can of course do the same things you did with the enums with variables |
You can of course do the same things you did with the enums with variables |
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UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Stats, Meta = (DisplayName = "Armor")) |
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Stats, Meta = (DisplayName = "Armor")) |
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Sounds sweet? It is! |
Sounds sweet? It is! |
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===== Functions ===== |
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You can expose functions like this: |
You can expose functions like this: |
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UFUNCTION(BlueprintCallable, Category = "Data Access") |
UFUNCTION(BlueprintCallable, Category = "Data Access") |
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int32 getArmor(); |
int32 getArmor(); |
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==== Instantiating UE classes ==== |
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===== Actors ===== |
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The most simple code that works is something like |
The most simple code that works is something like |
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GetWorld()->SpawnActor<AMyFirstActor>(); |
GetWorld()->SpawnActor<AMyFirstActor>(); |
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There are of course multiple ways to do it and just SpawnActor has like 7 or so overloads. |
There are of course multiple ways to do it and just SpawnActor has like 7 or so overloads. |
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===== UClass ===== |
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If you want to instantiate a U* class instead of an actor then you'll probably be using something like |
If you want to instantiate a U* class instead of an actor then you'll probably be using something like |
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UAcRandomScaleChange* pAcRandomScaleChange = CreateDefaultSubobject<UAcRandomScaleChange>("RandomScaleChange"); |
UAcRandomScaleChange* pAcRandomScaleChange = CreateDefaultSubobject<UAcRandomScaleChange>("RandomScaleChange"); |
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</blockquote> |
</blockquote> |
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===== Examples ===== |
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* [[Unreal Engine, from C++ spawn Blueprint inherited from C++ class, very small example]] |
* [[Unreal Engine, from C++ spawn Blueprint inherited from C++ class, very small example]] |
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* [[Unreal Engine, from C++ add an ActorComponent to an Actor, very small example]] |
* [[Unreal Engine, from C++ add an ActorComponent to an Actor, very small example]] |
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== Iterating == |
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The following code really works. No "GetWorld()", no fumbling and no idea if it has drawbacks. |
The following code really works. No "GetWorld()", no fumbling and no idea if it has drawbacks. |
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} |
} |
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== Delegates == |
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Methods for delegates seem to need to have the return type "void". So, if you need a return value, use some referenced parameter like |
Methods for delegates seem to need to have the return type "void". So, if you need a return value, use some referenced parameter like |
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bool& bOk |
bool& bOk |
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</blockquote> |
</blockquote> |
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=== Other types of Delegates === |
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==== One Parameter ==== |
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DECLARE_DELEGATE_OneParam(FParamDelegateSignature, int) |
DECLARE_DELEGATE_OneParam(FParamDelegateSignature, int) |
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.....->getDelegateWithParam02().ExecuteIfBound(42); |
.....->getDelegateWithParam02().ExecuteIfBound(42); |
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==== Multicast ==== |
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If you use "BindUObject" multiple times on the same delegate, only the last bind will be remembered. |
If you use "BindUObject" multiple times on the same delegate, only the last bind will be remembered. |
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If you want to have multiple listeners at once, you use the multicast delegate: |
If you want to have multiple listeners at once, you use the multicast delegate: |
Revision as of 19:15, 30 May 2024
Installation
- UE5: https://www.unrealengine.com
- Do NOT install 5.3 if you don't have VERY good reasons
- DO install 5.4+
- ASP.NET Core Runtime 3.1.32
https://dotnet.microsoft.com/en-us/download/dotnet/3.1 https://dotnet.microsoft.com/en-us/download/dotnet/thank-you/runtime-desktop-3.1.32-windows-x64-installer
- Visual Studio 2022: https://visualstudio.microsoft.com/downloads/
- Workloads / Desktop development with C++ (was suggested by Visual Studio when I loaded a UE5 project)
- Workloads / .NET desktop development (was suggested by Visual Studio when I loaded a UE5 project)
- Workloads / Game Development with C++
- don't unselect anything
- Windows 10 SDK (1.0.20*)
- Unreal Engine Test Adapter
- Unreal Engine uproject support
- Individual components / .NET 6.0 Runtime (Long Term Support) (was suggested by Visual Studio when I loaded a UE5 project)
- Individual components / .NET Framework 4.8.1 SDK (or higher)
- Individual components / .NET Framework 4.6.2 targeting pack (was suggested by Visual Studio when I loaded a UE5 project)
- Individual components / MSVC 143 - VS 2022 C++ x64/x86 build tools (v14.36-17.6 or newer?) (was suggested by Visual Studio when I loaded a UE5 project)
- After you install VS 2022, look in the VS Installer at the "Update" button. Enabled? UE5.4+? Yes, update... no problem.
- Unreal Engine Visual Studio Integration Tool plugin: https://aka.ms/vsituemarketplace (repeat after new engine installation, as of 2024-05-28: available for 5.4)
- naming convention checker: ".editorconfig" parallel to your .uproject file.
Content: https://raw.githubusercontent.com/microsoft/vc-ue-extensions/main/Source/.editorconfig - HLS configuration file: "shadertoolsconfig.json" parallel to your .uproject file.
Content: automatically created, defaults to:
{ "hlsl.preprocessorDefinitions": { }, " hlsl.additionalIncludeDirectories": [ ], "hlsl.virtualDirectoryMappings": { } }
Links
- The Unreal Engine Game Framework: From int main() to BeginPlay (video)
- Multiplayer in Unreal Engine: How to Understand Network Replication (video)
- Error compiling the Automation Tool after updating Visual Studio today (Unreal 5.3.2)
Unreal Engine
Blender
- Export Options (so that the object is not lying on the side after Export/Import):
- Forward: Y Forward
- Up: Z up
- Changing the object's origin to its bottom:
- Switch to Edit Mode if needed (Tab). With vertex selection on, choose the center vertex in the bottom. Press Shift+S and choose Cursor to Selected. The 3D cursor will move to the selected vertex. Deselect all and switch to Object Mode (Tab).
- In Tools choose Set Origin and then Origin to 3D Cursor.
- Make sure the object's coordinates are set to 0,0,0. Now the object should be placed properly on the XY plane.
C++
Variable names
If you want to use real variable names but have nice names in the UE editor too, then use meta/DisplayName
UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Camera, Meta = (DisplayName = "First Person Camera Component") ) UCameraComponent* m_pFirstPersonCameraComponent;
owner / client /server
The instance that spawned the class is always ROLE_Authority. If an Actor is spawned on the client, the client is the authority. -- OmaManfred
OmaManfred::
And concerning the owner stuff: When you spawn an instance of a class on the server FOR Client A, you have to set him as the owner. FActorSpawnParameters params; params.Owner = PlayerAPlayerController; SpawnActor<Class>(Class:StaticClass(),params); Then on Client B you can say IsOwner(PlayerBPlayerController), which should return false.
Logging
The following is just a copy/paste/change from the UE4 wiki and was really done from different persons, I am just using the work of different people here.
Put it in a Log.h and include it in .cpp files where you want to use these macros.
#pragma once #include "CoreMinimal.h" // macros // - LOG_LINE; // - PLOG_LINE; // - LOG -> output log // -- LOG("text"); // -- LOG("textStatic %s %.2f %d", L"textDynamic", 1.2, 5); // - PRINT -> screen // -- PRINT("text"); // -- PRINT("textStatic %s %.2f %d", L"textDynamic", 1.2, 5); // - PLOG -> output log + screen // -- PLOG("textStatic %s %.2f %d", L"textDynamic", 1.2, 5); #if _MSC_VER #define FUNC_NAME TEXT(__FUNCTION__) #else // FIXME - GCC? #define FUNC_NAME TEXT(__func__) #endif #define LOG_LINE UE_LOG(LogTemp, Warning, TEXT("%s, file: %s, line %d"), FUNC_NAME, *FString(__FILE__), __LINE__); #define PLOG_LINE \ { \ LOG_LINE; \ PRINT("%s, file: %s, line %d", FUNC_NAME, *FString(__FILE__), __LINE__); \ } #define PRINT(format, ...) \ { \ const FString sFunc = FString::Printf(TEXT("%s"), FUNC_NAME); \ const FString sText = FString::Printf(TEXT(format), ##__VA_ARGS__); \ const FString sMsg = FString::Printf(TEXT("%s() : %s"), *sFunc, *sText); \ if (GEngine) GEngine->AddOnScreenDebugMessage(-1, 5, FColor::White, sMsg); \ } #define LOG(format, ...) \ { \ const FString sMsg = FString::Printf(TEXT(format), ##__VA_ARGS__); \ UE_LOG(LogTemp, Warning, TEXT("%s() : %s"), FUNC_NAME, *sMsg);\ } #define PLOG(format, ...) \ { \ LOG(format, ##__VA_ARGS__); \ PRINT(format, ##__VA_ARGS__); \ }
Example Usage
#include "Log.h"
LOG_LINE; PLOG_LINE; // still being tested LOG("I am a line of text in the log,"); PRINT("but me, I am a line of text on the display screen, so there!");
LOG("textStatic %s %.2f %d", L"textDynamic", 1.2, 5); PRINT("textStatic %s %.2f %d", L"textDynamic", 1.2, 5); PLOG("textStatic %s %.2f %d", L"textDynamic", 1.2, 5);
FString sPssst("a Secret"); PLOG("I am telling you: %s", *sPssst);
Custom Log
If you want your own selectable category in the log filter to be able to only show your log messages, then you have to
- add this line in the Log.h above any defines:
DECLARE_LOG_CATEGORY_EXTERN(aProjectLog, Log, All);
- replace all "LogTemp" with "aProjectLog"
- add this line to each .cpp where you want to use these macros:
DEFINE_LOG_CATEGORY(aProjectLog);
You will - in most cases - remove (nearly) all log messages when your code is running well. So... do this only if you need this, not because you think this is the "better" way to use it.
Am I client or server ?
To answer questions 1 and 2: you can use AActor::GetNetMode() which returns whether you are a listen server, dedicated server or network client. if (GetNetMode() == ENetMode::NM_ListenServer) { } The ENetMode values are: NM_Standalone = 0 NM_DedicatedServer = 1 NM_ListenServer = 2 NM_Client = 3 // is only when you are actually connected to a server The ordering of the ENetMode values allows you to check multiple things at once: GetNetMode() <= 2 means you are the server or standalone, so you have 'global authority'.
UMG with C++ base class
- create a normal UMG widget
- create a C++ class with base class UserWidget (UUserWidget)
- build the project
- set the parent class of the UMG widget to your C++ class
- in <Project>.Build.cs add "UMG", "SLATE", "SLATECORE":
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "UMG" }); PrivateDependencyModuleNames.AddRange(new string[] { }); // Uncomment if you are using Slate UI PrivateDependencyModuleNames.AddRange(new string[] { "Slate", "SlateCore" });
- put into <Project>.h
#include "Runtime/UMG/Public/UMG.h" #include "Runtime/UMG/Public/UMGStyle.h" #include "Runtime/UMG/Public/Slate/SObjectWidget.h" #include "Runtime/UMG/Public/IUMGModule.h" #include "Runtime/UMG/Public/Blueprint/UserWidget.h"
SLATE
The "canvas" in UMG is "SConstraintCanvas" in Slate.
Multiplayer / Sessions
Do not search for "multiplayer", search for "sessions".
This is a Youtube video I found which gives you an overview, so you already have an idea how it works before you start learning the details: Multiplayer in Unreal Engine: How to Understand Network Replication.
String conversions
from: https://docs.unrealengine.com/en-us/Programming/UnrealArchitecture/StringHandling/FString
FString TestHUDString = FString(TEXT("This is my test FString.")); FName TestHUDName = FName(*TestHUDString); FText TestHUDText = FText::FromString(TestHUDString);
Classes
- You can create and use normal C++, like, create a normal C++ class and use new and delete with it.
- But if you want to use UE stuff, you must use UE stuff and be sure to not mix it with normal C++ handling. This sounds complicated, but it is just a reminder to for example never use "new" for an actor.
- You can create classes however you want:
- Get the UE editor to create them (Slow, but it just works. If you don't know better, use this!)
- Use the UI of your source editor (Visual Studio for example) to create them
- create them manually (I still have to modify the properties of the created .cpp files, not funny)
UE classes
Please keep in mind that my information might be wrong.
A very common error seems to be the naming of the files. You have to know that common UE classes have an 'U' in front of the class name and actors have an 'A' there. So, if you'd like a 'MyFirstActor', then
- the files are MyFirstActor.h and MyFirstActor.cpp
- the class is "AMyFirstActor"
- the generated file is "MyFirstActor.generated.h"
If you think you know what you are doing and use Visual Studio to create a new class "AMyFirstActor" it will default to the file names AMyFirstActor.h and AMyFirstActor.cpp which is wrong. I mean, it is not wrong, but it is not what you need here. :-)
About categories, there seem to be some ... reserved? ones. Whatever the reason, they don't work. I never got the category "Test" to show, there should be others. So, do not use "Test" as category if you have the same effect, just change the category name instead of trying to force it.
DLLEXPORT
Your classes will be inside a DLL and have to be exported to be usable. If you use UE to create a class you will see something like this:
class P01_TEST_API AMyFirstActor : public AActor
The "P01_TEST_API" between "class" and your class's name is probably just a define like
#define P01_TEST_API DLLEXPORT
Now you ask of course why there is a different define for each project if it is just "DLLEXPORT"? Good question. Next. Sorry. I just don't know (yet).
Update:
Ok, I have an idea.
If you want to use the same header files but without "DLLEXPORT", then you just change the define. And that has - of course - to be done per project. So, yes, it does make sense.
minimum
The minimum of a UE class would be like this:
header file
#pragma once #include "CoreMinimal.h" #include "GameFramework/Actor.h" #include "MyFirstActor.generated.h" UCLASS() class P01_TEST_API AMyFirstActor : public AActor { GENERATED_BODY() public:
Source file
#include "MyFirstActor.h"
*.generated.h
#include "MyFirstActor.generated.h"
Write it just like that, you don't create it, you don't look into it, you don't really care about it. BUT you have to include it as LAST include file in your header file.
UCLASS()
This has just to be there. For certain things to work you have to add words inside the brackets. An example would be:
UCLASS(BlueprintType, Blueprintable)
These words do what they say. You can use the class as a type in a blueprint or you can create a blueprint from this class.
GENERATED_BODY()
The default for a struct is public and the default for a class is private. That means "GENERATED_BODY()" in this code
class P01_TEST_API AMyFirstActor : public AActor { GENERATED_BODY()
is private.
Don't think, just put it before any access specifiers, it works.
Variables and the like
You might want certain functionality from UE for certain enums, member variables or methods. Like.. it should work as expected and not be cleared by the system which seems to be able to be happen to certain UE container classes if you don't make them UE properties.
If you don't see the changes from C++ in your blueprint, try "Asset Actions" / Reload
And if you don't see variables or stuff you would expect to see, right-click into the blueprint's graph and try "get<YourVariable>".
- UPROPERTY(BlueprintReadWrite, EditAnywhere, Category = "Misc", Meta=(DisplayName="Cool Name"))
Enums
UE enums must be outside of classes (since 4.12). This means you have to be creative with your naming or will slap yourself if you have two enum types which you called EStatus. (This might not even be possible now.)
Example: Header, before the class:
UENUM() enum AMySuicideActor_EStatus { Task UMETA(DisplayName = "Task"), Idle UMETA(DisplayName = "Idle"), };
Inside the class:
protected: UPROPERTY() TEnumAsByte<AMySuicideActor_EStatus> m_eStatus;
Inside the .cpp
m_eStatus = AMySuicideActor_EStatus::Idle;
Now, that is nice and all but why would you want it? BECAUSE! No, really, you can now change
UPROPERTY() TEnumAsByte<AMySuicideActor_EStatus> m_eStatus;
to
UPROPERTY(BlueprintReadWrite, EditAnywhere, Category = "My Tests | Part 1", meta = (DisplayName = "Status") ) TEnumAsByte<AMySuicideActor_EStatus> m_eStatus;
and suddenly you fall in love with UE. This is an actor, so you can drag it into the world in the UE editor. And then you can see the category "My Tests" and below it the subcategory "Part 1" and inside you see a label "Status" and behind it a combo box with the two possible selections: "Idle" and "Task".
- BlueprintReadWrite: blueprints can read and write this thing/property/variable.
- EditAnywhere: Edit it in the "Details" and (sometimes) in the "class defaults" and .. oehm.. no idea if there are more places.
- Category: The area where this data is put when you look at an instance/class/blueprint of it
- DisplayName: The name which is used to show this data's label (instead of the variable name)
Variables
You can of course do the same things you did with the enums with variables
UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Stats, Meta = (DisplayName = "Armor")) float m_fArmor;
There you are. Now you can edit the m_fArmor variable of your instance directly in the editor, after you created an instance by dragging the class into the world, of course.
Sounds sweet? It is!
Functions
You can expose functions like this:
UFUNCTION(BlueprintCallable, Category = "Data Access") int32 getArmor();
Instantiating UE classes
Actors
The most simple code that works is something like
GetWorld()->SpawnActor<AMyFirstActor>();
There are of course multiple ways to do it and just SpawnActor has like 7 or so overloads.
UClass
If you want to instantiate a U* class instead of an actor then you'll probably be using something like
UAcRandomScaleChange* pAcRandomScaleChange = CreateDefaultSubobject<UAcRandomScaleChange>("RandomScaleChange");
but I can't say anything about it (yet). It works but ... understanding.... hehe.
I found the following sentence, I don't know yet if it is true. But if it is true, you really want to know it:
CreateDefaultSubobject works only in constructor. Everywhere else use NewObject.
Examples
- Unreal Engine, from C++ spawn Blueprint inherited from C++ class, very small example
- Unreal Engine, from C++ add an ActorComponent to an Actor, very small example
Iterating
The following code really works. No "GetWorld()", no fumbling and no idea if it has drawbacks.
#include "Components/PointLightComponent.h"
for (TObjectIterator<UPointLightComponent> it; it; ++it) { UPointLightComponent* pPlc = *it; pPlc->SetVisibility(false); }
Delegates
Methods for delegates seem to need to have the return type "void". So, if you need a return value, use some referenced parameter like
bool& bOk
The idea
If a class says, "I have delegates, and therefore I am super cool"
DECLARE_DELEGATE(FStandardDelegateSignature) UCLASS() class XY_API AWithDelegate : public ...
and then has members like
FStandardDelegateSignature m_standardDelegate01;
then another (or the same) class can say, "hey, I want you to execute some code of me if your delegate01 is activated":
AWithDelegate*......->m_standardDelegate01.BindUObject(this, &AThisIsMe::coolFunctionYouShouldCall);
and then a third class can say, "yo my man, if you have something connected to your delegate01, pretty please execute that stuff now":
AWithDelegate*......->m_standardDelegate01.ExecuteIfBound();
You would - of course - not give access to your member variable directly but instead use something like
public: FStandardDelegateSignature& getStandardDelegate01(); protected: FStandardDelegateSignature m_StandardDelegate01;
disconnect
->getDelegateWithParam02().Unbind();
Do the connecting in BeginPlay and the disconnecting in EndPlay if you don't know better.
Other types of Delegates
One Parameter
DECLARE_DELEGATE_OneParam(FParamDelegateSignature, int)
FParamDelegateSignature m_ParameterDelegate02;
FParamDelegateSignature& getDelegateWithParam02();
.....->getDelegateWithParam02().ExecuteIfBound(42);
Multicast
If you use "BindUObject" multiple times on the same delegate, only the last bind will be remembered. If you want to have multiple listeners at once, you use the multicast delegate:
DECLARE_MULTICAST_DELEGATE(FMulticastDelegateSignature)
FMulticastDelegateSignature& getMulticastDelegate03();
FMulticastDelegateSignature m_MulticastDelegate03;
m_DelegateHandle03 = .....->getMulticastDelegate03().AddUObject(this, &AMulticastDelegateListener::MyCoolFunction);
......->getMulticastDelegate03().Remove(m_DelegateHandle03);
.....->getMulticastDelegate03().Broadcast();
Custom Events
One class says it will have a custom event "CeBeginOverlap" which is a completely free too choose name at this moment:
DECLARE_EVENT(AMyTriggerVolume, CeBeginOverlap) UCLASS() class P02_API AMyTriggerVolume : public AActor
Then it has of course to have that event:
public: CeBeginOverlap OnBeginOverlap;
Now this class will tell you at some point in time that this event has happened:
void AMyTriggerVolume::NotifyActorBeginOverlap(AActor* OtherActor) { OnBeginOverlap.Broadcast();
This is nice and everything, but now we need someone who is interested in that stuff. There a multiple ways, one would be something like this:
Super::BeginPlay(); for (TObjectIterator<AMyTriggerVolume> it; it; ++it) { AMyTriggerVolume* pTrigger = *it; pTrigger->OnBeginOverlap.AddUObject(this, &AYourListenerClass::OnTriggerEvent); }
The advantage would be that you would connect to every source of this type.
Another way would be to have something like this in the header:
UPROPERTY(EditAnywhere) AMyTriggerVolume* m_pEventSource;
and then set the source in the UE-Editor and use code like this
if (m_pEventSource!= nullptr) { m_pEventSource->OnBeginOverlap.AddUObject(this, &AYourListenerClass::OnTriggerEvent); }
Enhanced Input
- An (U)InputAction is just a name. Like "action1", "jump" or "move". They have no meaning by itself.
- A character might have multiple of these.
- An (U)InputMappingContext has two reasons for existence:
- Map a key/mouse/control to an (U)InputAction
- Collect multiple InputActions
- A (A)PlayerController might manage one or more of these
- A character's "SetupPlayerInputComponent" will connect InputActions to methods.
So you have:
Input -> InputMappingContext -> InputAction -> Method
Example
- Unreal Engine, C++ Enhanced Input, very small example
- Tutorial for a different way to use it, by Kochab (not verified yet)
UE Editor
Escape key stops simulation in editor
If you want to change this behavior, open "Edit/Editor Preferences" and search for "stop". Then change under "Play World/Stop" the shortcut "Escape" to whatever you want, for example shift-Escape.
Details/Text/Line-Break
If you are shown a text in the Details tab, chances are you can use shift-return to create a line break.
Removing projects from "Project Open" dialog
Open (use the correct engine version)
%USERPROFILE%\AppData\Local\UnrealEngine\5.3\Saved\Config\WindowsEditor\EditorSettings.ini
and modify/remove
CreatedProjectPaths RecentlyOpenedProjectFiles
Volume of Sound after building in Visual Studio
- Content Drawer / Settings / Show Engine Content
- Engine / Content / EditorSounds / Notifications / *_Cue
- Volume Multiplier
Migrating Blueprint which has C++ class as parent
Variant that works for me and is a lot of work
c++
- copy the c++ *.h and *.cpp files to the other project
- right-click the DLLEXPORT macro (class bla_API YourClass, here bla_API is meant) in one of the copied header files
- select "rename"
- give the DLLEXPORT macro of your new project
- skip: yes
- scop: current project
- apply
- select "rename"
- compare the YourProject.Build.cs between the two projects, add modules as needed
- re-generate or refresh the c++-project from the UE-Editor (probably for the includes in .cpp/properties/nmake)
- make sure the project can compile and link before you do the next steps
Blueprints
- open "YourProject\Config\DefaultEngine.ini"
- add (or goto)
[/Script/Engine.Engine]
- add the following line for each of your classes (Do NOT give the prefix letters, like A or U)
+ActiveClassRedirects=(OldClassName="/Script/EI01.MyCharacter",NewClassName="/Script/P03.MyCharacter")
- Close the UE-Editor with the new project
- Open the UE-Editor with the old project
- Open the UE-Editor with the new project
- select the blueprints you want to migrate
- right-click
- asset actions
- migrate
- select the content folder of the new project
- in the UE-Editor with the new project
- open each of the migrated blueprints once
- compile
- save
- open each of the migrated blueprints once
Variants that don't work for me and would be so easy to use
There should be a better variant, I read you can add something like this
[CoreRedirects] +ClassRedirects=(MatchSubstring=True,OldName="MyOldProjectName",NewName="MyNewProjectName")
and it should work for the whole project without having to do it for every class.
I read another variant where you do something like
ClassRedirects=(MatchSubstring=True,OldName="/MyOldProjectName",NewName="/MyNewProjectName")
These two variants do either nothing or make my UE-Editor unable to load the project. Too bad, I'd like to have less work. :-(
But you can try them, maybe you are lucky. Or you understand what you are doing and do it right.
Source control
Don't use Mercurial (or git) for game development. That would be just plain stupid.
Use Subversion or something like that.
The minimum you have to put under source control:
/Config /Content /Source Project.uproject
Depending on your project:
/.editorconfig /shadertoolsconfig.json
For ignores, have a look at ignoring files with svn.
External Actors
Under "Content" you will probably after some time see "EXTERNAL_ACTOR" or stuff like that. These are your map's actors, so multiple people can work on different parts of the map at the same time. That is the theory I read. :-)
So, no, don't delete them.
Here is the documentation about it.
Developer Folder
If you have the developer folder(s) enabled "Content / View Options / Show Developers Content" then make sure to not reference it from outside when cooking a project.
Visual Studio
Show errors after build
Tools / Options / Projects and Solutions / Always show Error List if build finishes with errors
Generate Visual Studio Project file
To get a cleaner project you could create a "delete-temps.cmd" with content like the following (match it with your needs):
rmdir /s /q .vs rmdir /s /q Binaries rmdir /s /q Build rmdir /s /q DerivedDataCache rmdir /s /q Intermediate rmdir /s /q Releases rmdir /s /q Saved rmdir /s /q Intermediate del *.sln del .vsconfig
After you cleaned away the trash you can right-click your *.uproject file and select "Generate Visual Studio Project file". This might remove some problems. Or create new ones. So far it only helped me, but it IS a bit brutal, right?
Finding the include file for a class
- Select the class or just have your cursor inside the name
- Press ctrl+, (press ctrl and "comma" at the same time)
- Double-left-click the entry with the correct looking header file.
- Then you right-click the tab name and select "copy full path".
- Now you include that path and remove the beginning.
- How much to leave... "you much have to learn".
If the includes are correct and you want to see the header of something again:
- Press F12 with your cursor on the class you want to know about to go to the definition.
Just want to switch between header and source?
ctrl-k/-o
Meaning: hold ctrl, press 'k' once, after that press 'o' (letter, not digit) once while still holding ctrl.
Example 1
C:\ue\UE_5.4\Engine\Source\Runtime\Engine\Classes\Particles\ParticleSystemComponent.h
Correct include:
#include "Particles/ParticleSystemComponent.h"
Example 2
C:\ue\UE_5.4\Engine\Plugins\EnhancedInput\Source\EnhancedInput\Public\InputActionValue.h
Correct include:
#include "InputActionValue.h"
Misc
Other Licenses (examples)
not allowed
- GNU General Public License (GPL),
- Lesser GPL (LGPL) (unless you are merely dynamically linking a shared library), or
- Creative Commons Attribution-ShareAlike License.
Code or content under the following licenses, for example, are allowed
- BSD License,
- MIT License,
- Microsoft Public License, or
- Apache License.
Other
Black Screens or flickering/invisible new action popup
Errors
Visual Studio
cannot open source file "CoreMinimal.h"
Error List: "Build + Intelli Sense" => "Build Only"
(source)
I am pretty sure this is NOT a solution but a workaround.
Error MSB3073 [...] -WaitMutex -FromMsBuild" exited with code 6
If you want to build with Visual Studio and get something like
Error MSB3073 The command "C:\ue\UE_5.3\[...]ShowActor.uproject" -WaitMutex -FromMsBuild" exited with code 6.
then you can do this:
- UE-Editor
- Edit / Editor Preferences
- Live Coding
- Enable Live Coding: no
- Live Coding
- File / Save All
- Edit / Editor Preferences
Yes, you do this change in the EDITOR's preferences and YES, you have to do it for every project and YES, that makes absolutely NO sense at all.
IntelliSense Error: "can't open file" for includes or "red squiggles under my includes"
Make sure the .cpp-files have in Properties/NMake:
Include Search Path: $(ClCompile_AdditionalIncludeDirectories)
Copy it from other .cpp-files to be sure to get the correct value for your UE-Version/system.
Can't build Solution
- UE / Edit / Editor Preferences / Live Coding / Enable Life Coding: disable
- Use the context menu on your project and select "Set as Startup Project".
- Use "Build <project> (ctrl-B) to build.
This works for me but I am pretty sure there should be a way to have "Live Coding" enabled AND build from Visual Studio. I mean... the UE developers will themselves want to have both options, right? So it should be possible?
Update 1:
I found out that I have to fix the errors in the other (there are ca. 7) projects in the solution to be able to build the solution and to do that I'd have to get the source version of UE. Currently I am very unhappy with all this. A UE5 installation on top of a functioning UE4 installation works. But if you only install UE 5.3 onto a new system, not working :-(
Update 2:
UE 5.4 works pretty well. If you have 5.3, switch to 5.4+, if you are told by someone to install 5.3, ignore him and block him for like ever. And curse him!