Wiki Code Tutorials

[FONT=Comic Sans MS]USTRUCTS, UE4 C++ Structs

UE4 C++ Structs

[FONT=Comic Sans MS]I love UStructs!



New Wiki Section, Getting Nav Polys!

I’ve added a section showing you how to get the Nav Polys, the actual individual units of the nav mesh system, so you can do completely custom calculations like I do in this video below!

Wiki: Custom UE4 C++ AI Coding



Added a second tutorial, how to get the screen-size of any actor :slight_smile: Useful for scaling widgets like the image below:

Get Screen-Size Bounds of An Actor

Hope it helps people!

@The Jamsh

Thanks for your awesome wiki contribution, wohooo! Really useful!

**Use C++ Operator New Instead of Malloc**

Using Malloc does not initialize the Vtable! So virtual functions will crash!

I recommend that you use C++ operator **new** to get around this, which both

a. calls the constructor of the data type
b. properly initializes the VTable (virtual function table)

I updated my wiki with this information

**UE4 Dynamic Memory Management**



Dear Community,

I recently wrote a wiki on how to add to the UE4 C++ AI path following system, to add in custom pathing coding!

UE4 Wiki Link: Writing Custom C++ AI Code

Well I now have my best demo yet of the effectiveness of this coding structure!

I prove to you in the video that I am using just multi-threaded C++ to dynamically calculate AI Jump paths for my AI units to follow the player through many complex jumping sequences!

  1. I am using just C++ coding, no helpers in the editor!

2.** In this thread I share my own UE4 C++ code with you** for how to get all the nav polys, the actual portions of the nav mesh so that you can do your own fancy custom UE4 C++ AI pathing code!

  1. In this thread I also show you how I know when the UE4 pathing system can’t find a way to the player without doing jumps!

**Video: Rama's Multi-Threaded C++ AI Jump Pathing**

Once again, I am doing all the jumping calculations **dynamically via C++** using the nav areas and my custom path following component!


The code I use in this video is multi-threaded using the UE4 C++ Task Graph system:

UE4 Wiki Link: UE4 Multi-threading

**C++ Code For You**

I inject my custom AI jump pathing code in this way:


        Custom UE4 C++ AI Path Follow Component

	By Rama


#pragma once

#include "Navigation/PathFollowingComponent.h"		

class UJoyPathFollowComp : public UPathFollowingComponent
	UJoyPathFollowComp(const FObjectInitializer& ObjectInitializer);

/** follow current path segment */
virtual void FollowPathSegment(float DeltaTime) override;




void UJoyPathFollowComp::FollowPathSegment(float DeltaTime)
	//Pointer Safety Checks
	if (MovementComp == NULL || !Path.IsValid())
	//Use Jump/Fall Pathing?
	if(Path->IsPartial()) //AI could not reach player, try using jump pathing!
                //I send out instructions to my custom character class here
	//Proceed normally (no jump pathing)



FollowPathSegment is the main UE4 Path Follow tick function, and so when you want to add completely custom coding you can use this function as your starting point to adjust normal UE4 pathing behavior!

Path is Partial

The way I tell whether I need to try using custom jump pathing code is whether or not the UE4 Pathing system has detected a partial path!

Then my AI jump code runs and teaches the AI to get to the player using C++ calculated Jumps!

if(Path->IsPartial()) //AI could not reach player, try using jump pathing!

**How to Get all the UE4 Nav Polys**

In the video above you will see I get all the UE4 Nav Polys in order to do all my C++ AI Jump calculations!

Here's the function I wrote to do this, just for you!


**// Rama UE4 C++ AI Code for you!
//     add this to your custom path follow component!**

**//Nav Data Main**
FORCEINLINE const ANavigationData* **GetMainNavData**(FNavigationSystem::ECreateIfEmpty CreateNewIfNoneFound)
	UNavigationSystem* NavSys = GetWorld()->GetNavigationSystem();
	if(!NavSys) return NULL; 
	return NavSys->GetMainNavData(CreateNewIfNoneFound);

**//Choose Which Nav Data To Use**
FORCEINLINE const ANavigationData* **JoyGetNavData()** const
              return GetMainNavData();

	const FNavAgentProperties& AgentProperties = MovementComp->GetNavAgentPropertiesRef() ;
	const ANavigationData* NavData = GetNavDataForProps(AgentProperties) ;
	if (NavData == NULL)
		NavData = GetMainNavData();
	return NavData;

FORCEINLINE bool **TileIsValid**(const ARecastNavMesh* NavMesh,int32 TileIndex) const
	if(!NavMesh) return false;
	const FBox TileBounds = NavMesh->GetNavMeshTileBounds(TileIndex);
	return TileBounds.IsValid != 0;

bool **NavPoly_GetAllPolys**(TArray<NavNodeRef>& Polys);



**//Rama's UE4 Nav code to get all the nav polys!**

bool UJoyPathFollowComp::****NavPoly_GetAllPolys****(TArray<NavNodeRef>& Polys)
	if(!MovementComp) return false;
	//Get Nav Data
	const ANavigationData* NavData = JoyGetNavData();
	const ARecastNavMesh* NavMesh = Cast<ARecastNavMesh>(NavData);
		return false;
	TArray<FNavPoly> EachPolys;
	for(int32 v = 0; v < NavMesh->GetNavMeshTilesCount(); v++)
                //CHECK IS VALID FIRST OR WILL CRASH!!! 
               //     256 entries but only few are valid!
               // using continue in case the valid polys are not stored sequentially!
	//Add them all!
	for(int32 v = 0; v < EachPolys.Num(); v++)



Have fun writing custom UE4 AI C++ code and getting all the nav polys so you can truly do whatever you want with UE4’s awesome navigation system!


**New Wiki Section

Shorthand Forward Declaration**

I added a new section and also polished up my Forward Declaration Wiki!

Forward Declaration ~ Shorthand Forward Declaration



Just added another tutorial of my own, Spawning different Pawns for different Players in Multiplayer!

Hope this helps people :slight_smile:

Thanks for sharing TheJamsh!



Tutorial: How to use UPhysicsConstraintComponent inside OnConstruction(FTransform) override function

I wanted to try contributing to the wiki with a tutorial. I noticed that Rama had already made an article here in regards to Physics Constraint Components and creating them dynamically. All I wanted to do is to just extend that article, so it also touches on ObjectInitializer, why we shouldn’t initialize physics constraint components in OnConstruction(Transform) function (which I really don’t know), and other ways to dynamically create physics constraint components.

If I edit Rama’s article, it will easily get reverted because I do not have a polished code at the moment. Therefore, I will be posting my extension here, and hopefully someone could give me tips. Feedback is welcomed.


I wanted to be able to spawn actors and constrain the actors in a given space like a chain or a line from my base class to the end. I know that to spawn actors, I need to call on SpawnActor() any function that is not going to be called in the constructor. However, I am having trouble with the UPhysicsConstraintComponent where it would fail to be created when I call on CreateDefaultSubobject() in the OnConstruction(Transform) override function of my base class. The only thing I know that will allow me to set UPhysicsConstraintComponent successfully is by initializing it in the constructor.

I did another alternate method where I would store three TArrays in the base class, with each of them representing the subclass, physics constraint component, and the constraint names. The following code is placed in the base class’ header file. I use APawn because, frankly, everything is in APawn.

class TUTORIAL_API ABaseClass : public APawn
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category=CustomProperties) TArray<ASubClass*> SubClassArray;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category=CustomProperties) TArray<UPhysicsConstraintComponent*> PhysicsConstraintArray;
	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category=CustomProperties) TArray<FName> ConstraintNameArray;

Then to initialize the arrays, first you need to create the following components for the PhysicsConstraintArray and the ConstraintNameArray.

ABaseClass::ABaseClass(const FObjectInitializer& ObjectInitializer) : Super(ObjectInitializer)
	for (int32 i = 0; i < 4; i++){
		FString Name = "Frame_" + FString::FromInt(i);

		//Physics Constraints
		UPhysicsConstraintComponent* PhysicsConstraint = ObjectInitializer.CreateDefaultSubobject<UPhysicsConstraintComponent>(this, this->ConstraintNameArray*);

Then in the OnConstruction(Transform) override function, you would then start initializing the subclass array. Note that the ConstraintNameArray.Num() is then used as an array size counter, so you don’t have to define constants here and there.

void ABaseClass::OnConstruction(const FTransform& Transform){

	//First loop needs initial values passed in, so successive calls can then be swapped for last initialized actors.
	FVector Height(0.0f, 0.0f, 100.0f); //How high from the initial world origin. Since the default floor mesh in a blank level is 80 UE4 units high, I set it to 100.
	FActorSpawnParameters Params;
	Params.Owner = this; //Setting the owner as the base class. When spawning actors, actors will have the owner as their parents.
	USceneComponent* Scene = this->GetRootComponent();
	UPrimitiveComponent* Primitive = this->BoxCollider;

	//Initializing Subclass array.
	for (int32 i = 0; i < ConstraintNameArray.Num(); i++){
		ASubClass* Class = this->GetWorld()->SpawnActor<ASubClass>(ASubClass::StaticClass(), Height, this->GetActorRotation(), Params);
		//Set whatever constraining limits you need here
		UPhysicsConstraintComponent* Physics = this->PhysicsConstraintArray*;
		Physics->AttachTo(Scene, NAME_None, EAttachLocation::KeepWorldPosition);
		Physics->SetConstrainedComponents(Primitive, NAME_None, Class->BoxCollider, NAME_None);
		Physics->SetAngularSwing1Limit(EAngularConstraintMotion::ACM_Locked, 0.0f);
		Physics->SetAngularSwing2Limit(EAngularConstraintMotion::ACM_Locked, 0.0f);
		Physics->SetAngularTwistLimit(EAngularConstraintMotion::ACM_Locked, 0.0f);
		//Prepare for next iteration.
		Params = {};
		Params.Owner = Class;
		Scene = Class->GetRootComponent();
		Primitive = Class->BoxCollider;

That is all.

Hi All,

I just created a tutorial on making an editor module A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums. I hope someone finds it useful!

This is my first tutorial so let me know if there is anything I should be doing differently in terms of style.

I’ve got another one coming up on component visualizers and then maybe one on custom editor modes if I’ve still got the energy.

Hi All Again,

As promised I’ve made another tutorial on using component visualizers: A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums. Please feel free to give me some feedback on it!

These are awesome! Nice work :slight_smile:

New Tutorial, how to clear UMG Widgets between opening/closing levels.

Note: This is probably a workaround for a bug. I would Submit a Pull Request, but I’m not sure how!

**New Wiki

How to Use a Custom Skeletal Mesh Component Class with your ACharacter Extending Class!**

In this tutorial I show you how you can easily change your ACharacter class to use a custom USkeletalMeshComponent at any time during your project’s development cycle!

No custom APawn class tree required! Just a simple change to your ACharacter constructor!


Class and Line Number for your Screen and Log Messages!

Dear Community,

I am giving you easy-to-use pre-processor commands to get a UE4 String that tells you the Class Name, Function Name, and Line Number of the calling code!

Logs, Printing the Class Name, Function Name, and Line Number of your Calling Code!



After you get my .h file below, the code for the above picture is this!


//~~~ Tick ~~~
void AEVCoreDefense::Tick(float DeltaTime)

	VSCREENMSG("Got Here!");  //Class and line number get printed for you! ♥ Rama


UE_LOG Versions

I’ve also added several macros to support adding class and line number information to UE_LOG messages!

//This will print the class and line number along with the character name!
V_LOG2(YourLogCat, "Hit Character Name is",Hit.GetActor()->GetName());


**Here is the entire file you can #include in your code base!**

I made this a file called JoyCurrentClassFuncLine.h

So you would then do this somewhere at the top of one of your core classes:


// Joy Class Func Line
**#include "JoyCurrentClassFuncLine.h"**



	Joy String 
		Current Class, File, and Line Number!
			by Rama
	PreProcessor commands to get 
		a. Class name
		b. Function Name
		c. Line number 
		d. Function Signature (including parameters)
	Gives you a UE4 FString anywhere in your code that these macros are used!
		You can use JOYSTR_CUR_CLASS anywhere to get a UE4 FString back telling you 
		what the current class is where you called this macro!
		This macro prints the class and line along with the message of your choosing!
		VSCREENMSG("Have fun today!");
	<3  Rama
#pragma once
//Current Class Name + Function Name where this is called!
//Current Class where this is called!
#define JOYSTR_CUR_CLASS (FString(__FUNCTION__).Left(FString(__FUNCTION__).Find(TEXT(":"))) )
//Current Function Name where this is called!
#define JOYSTR_CUR_FUNC (FString(__FUNCTION__).Right(FString(__FUNCTION__).Len() - FString(__FUNCTION__).Find(TEXT("::")) - 2 ))
//Current Line Number in the code where this is called!
#define JOYSTR_CUR_LINE  (FString::FromInt(__LINE__))
//Current Class and Line Number where this is called!
//Current Function Signature where this is called!
//Victory Screen Message
// 	Gives you the Class name and exact line number where you print a message to yourself!
#define VSCREENMSG(Param1) (GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *(JOYSTR_CUR_CLASS_LINE + ": " + Param1)) )
#define VSCREENMSG2(Param1,Param2) (GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *(JOYSTR_CUR_CLASS_LINE + ": " + Param1 + " " + Param2)) )
#define VSCREENMSGF(Param1,Param2) (GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, *(JOYSTR_CUR_CLASS_LINE + ": " + Param1 + " " + FString::SanitizeFloat(Param2))) )
#define V_LOG(LogCat, Param1) 		UE_LOG(LogCat,Warning,TEXT("%s: %s"), *JOYSTR_CUR_CLASS_LINE, *FString(Param1))
#define V_LOG2(LogCat, Param1,Param2) 	UE_LOG(LogCat,Warning,TEXT("%s: %s %s"), *JOYSTR_CUR_CLASS_LINE, *FString(Param1),*FString(Param2))
#define V_LOGF(LogCat, Param1,Param2) 	UE_LOG(LogCat,Warning,TEXT("%s: %s %f"), *JOYSTR_CUR_CLASS_LINE, *FString(Param1),Param2)
#define V_LOGM(LogCat, FormatString , ...) UE_LOG(LogCat,Warning,TEXT("%s: %s"), 	*JOYSTR_CUR_CLASS_LINE, *FString::Printf(TEXT(FormatString), ##__VA_ARGS__ ) )





Get Float As String With Precision Using Epic’s FText Helpers

Dear Community,

I’ve updated my Get Float As String With Precision C++ wiki to use Epic’s FText helpers!

Now I am leveraging all of their awesome work to get a float as a string with any precision of your choosing, encapsulatd into an easy to use static library function.

My function also now gives you an option as to whether you want to include a leading zero for fractional numbers!

UE4 Wiki Link




**Featured Wiki

Read and Write to Config Files in UE4 C++!**

In this wiki I give you code that lets you read and write to config files any time you want, more so than just using UPROPERTY(config)

You can read and write any value you want, any time, directly in UE4 C++!

End result: a Human-readible, Human-editable file that your players can tweak to adjust your game’s settings after release!

Wiki Link
A new, community-hosted Unreal Engine Wiki - Announcements and Releases - Unreal Engine Forums,Read%26_Write_to_Config_Files



How To Do Custom C++ Logic in Animation Blueprints, Every Tick!

In this wiki I show you how you can add custom project-level C++ code to your Animation Blueprints!

This is code that you can run every animation tick!

This allows you as the C++ programmer to support your entire time by doing intense math calculations in C++, which is much faster than in BP!

This also lets you utiilze your entire C++ code base and custom data structures without having to expose it all to BP so that the animation blueprint can use it in the event graph!

Custom C++ Logic for Animation Blueprints




Thank you Rama for your great work! :slight_smile:

Hee hee!

You’re welcome!

Have fun today!