Introduction to Unreal Engine and C++ Programming

Distributed Programming

Lecture 04 - Introduction to Unreal Engine and

C++ Programming

Edirlei Soares de Lima

<edirlei.lima@universidadeeuropeia.pt>

Editor – Unity vs. Unreal

Recommended reading: Unreal Engine 4 For Unity Developers

https://docs.unrealengine.com/en-us/GettingStarted/FromUnity

Glossary – Unity vs. Unreal

Category

Effects

Game UI

Unity

Particle Effect

UI

Unreal Engine

Effect, Particle, Cascade

UMG

Skeletal Animation

System

Animation

2

D

Sprite Editor

C#

Script

Raycast

Rigid Body

Paper2D

C++

Blueprint

Line Trace, Shape Trace

Collision, Physics

Programming

Physics

Unreal Engine – Main Classes

UObject

AActor

UActorComponent

AGameModeBase

AController

ALight

APawn

USceneComponent

AAIController APlayerController

ADirectionalLight

ACharacter

UCameraComponent

First Game Tutorial

•

Concept: a game where the player must collect all coins and

then go to specific location to complete the level.

Gameplay elements:

–

Player character (walk and jump);

–

Collectible coins: after collecting all coins,

the player must go the “level complete” area

to finish the level.

–

Enemies (zombies): patrol the level and

attack the player. If the enemy touches the

player, is game over;

–

GUI messages: number of collected coins,

game over, and level completed messages;

First Game Tutorial

•

Create a new C++ Third Person Project:

First Game Tutorial

•

Base project:

•

Next step: create a collectible item (a coin).

First Game Tutorial

•

Low poly coin model:

–

http://www.inf.puc-rio.br/~elima/dp/coin.fbx

Importing the FBX model: drag and drop

Import Uniform Scale = 100.0

First Game Tutorial

•

Create a new C++ class: CollectibleCoin

CollectibleCoin.h

#pragma once

#

include "CoreMinimal.h"

include "GameFramework/Actor.h"

include "CollectibleCoin.generated.h"

UCLASS()

class MYFIRSTGAME_API ACollectibleCoin : public AActor

{

GENERATED_BODY()

public:

// Sets default values for this actor's properties

ACollectibleCoin();

protected:

/ Called when the game starts or when spawned

virtual void BeginPlay() override;

/

public:

// Called every frame

virtual void Tick(float DeltaTime) override;

};

CollectibleCoin.cpp

#include "CollectibleCoin.h"

// Sets default values

ACollectibleCoin::ACollectibleCoin()

{

// Set this actor to call Tick() every frame.

PrimaryActorTick.bCanEverTick = true;

}

/

/ Called when the game starts or when spawned

void ACollectibleCoin::BeginPlay()

{

Super::BeginPlay();

}

// Called every frame

void ACollectibleCoin::Tick(float DeltaTime)

{

Super::Tick(DeltaTime);

}

First Game Tutorial

•

Next step: define the structure of the collectible coin:

...

CollectibleCoin.h

#

include "Components/SphereComponent.h"

include "CollectibleCoin.generated.h"

...

protected:

UPROPERTY(VisibleAnywhere, Category = "Components")

UStaticMeshComponent* MeshComponent;

UPROPERTY(VisibleAnywhere, Category = "Components")

USphereComponent* SphereComponent;

virtual void BeginPlay() override;

...

First Game Tutorial

•

Next step: define the structure of the collectible coin:

...

CollectibleCoin.cpp

ACollectibleCoin::ACollectibleCoin()

{

PrimaryActorTick.bCanEverTick = true;

MeshComponent = CreateDefaultSubobject<UStaticMeshComponent>

("Mesh Component");

RootComponent = MeshComponent;

SphereComponent = CreateDefaultSubobject<USphereComponent>

("Sphere Component");

SphereComponent->SetupAttachment(MeshComponent);

}

.

..

First Game Tutorial

•

Next step: create a Blueprint Class for the collectible coin:

First Game Tutorial

•

In the Blueprint editor, select the mesh of the coin:

•

Then, compile the blueprint and place it in the level.

First Game Tutorial

•

Rotating the coin in the game:

...

CollectibleCoin.h

public:

UPROPERTY(EditAnywhere, Category = "Gameplay")

float RotationSpeed;

...

CollectibleCoin.cpp

void ACollectibleCoin::Tick(float DeltaTime)

{

Super::Tick(DeltaTime);

AddActorLocalRotation(FRotator(RotationSpeed * DeltaTime, 0, 0));

}

.

..

First Game Tutorial

•

Destroying the coin when the player collides:

...

CollectibleCoin.h

public:

..

virtual void NotifyActorBeginOverlap(AActor* OtherActor) override;

.

...

CollectibleCoin.cpp

void ACollectibleCoin::NotifyActorBeginOverlap(AActor* OtherActor)

{

Super::NotifyActorBeginOverlap(OtherActor);

Destroy(this);

}

...

First Game Tutorial

•

Setup the collision properties in the blueprint:

–

MeshComponent:

–

SphereComponent:

UProperty Specifiers

Property Tag

Effect

Indicates that this property is visible in all

property windows, but cannot be edited.

VisibleAnywhere

EditAnywhere

Indicates that this property can be edited

by property windows, on archetypes and

instances.

Indicates that this property can be edited

by property windows, but only on

archetypes.

EditDefaultsOnly

This property can be read by Blueprints,

but not modified.

BlueprintReadOnly

BlueprintReadWrite

This property can be read or written from

a Blueprint.

Indicates that this property can be edited

by property windows, but only on

instances, not on archetypes.

EditInstanceOnly

https://docs.unrealengine.com/en-US/Programming/UnrealArchitecture/Reference/Properties/Specifiers

UFunction Specifiers

Function Specifier

Effect

The function can be executed in a

Blueprint or Level Blueprint graph.

BlueprintCallable

The function can be implemented in a

Blueprint or Level Blueprint graph.

BlueprintImplementableEvent

The function is designed to be overridden

by a Blueprint, but also has a default

native implementation.

BlueprintNativeEvent

CallInEditor

The function can be called in the Editor on

selected instances via a button in the

Details Panel.

The function is an RPC (Remote Procedure

Call) service request.

ServiceRequest

ServiceResponse

This function is an RPC service response.

https://docs.unrealengine.com/en-US/Programming/UnrealArchitecture/Reference/Properties/Specifiers

First Game Tutorial

•

Spawning a particle system when the player collects the coin:

...

CollectibleCoin.h

protected:

...

UPROPERTY(EditDefaultsOnly, Category = "Effects")

UParticleSystem* CollectEffects;

void PlayEffects();

...

First Game Tutorial

•

Spawning a particle system when the player collects the coin:

#

include "Kismet/GameplayStatics.h"

..

CollectibleCoin.cpp

.

void ACollectibleCoin::NotifyActorBeginOverlap(AActor* OtherActor)

{

Super::NotifyActorBeginOverlap(OtherActor);

PlayEffects();

Destroy(this);

}

void ACollectibleCoin::PlayEffects()

{

UGameplayStatics::SpawnEmitterAtLocation(this, CollectEffects,

GetActorLocation());

}

First Game Tutorial

•

Counting the number of collected coins:

...

MyFirstGameCharacter.h

public:

void AddCoin();

..

.

protected:

UPROPERTY(BlueprintReadOnly, Category = "Gameplay")

int TotalCoins;

...

.

void AMyFirstGameCharacter::AddCoin()

..

MyFirstGameCharacter.cpp

{

TotalCoins++;

}

...

First Game Tutorial

•

Counting the number of collected coins:

...

CollectibleCoin.cpp

void ACollectibleCoin::NotifyActorBeginOverlap(AActor* OtherActor)

{

Super::NotifyActorBeginOverlap(OtherActor);

AMyFirstGameCharacter* character = Cast<AMyFirstGameCharacter>

(OtherActor);

if (character)

{

character->AddCoin();

PlayEffects();

Destroy(this);

}

.

..

First Game Tutorial

•

Quick way to see the result: blueprint

First Game Tutorial

•

Quick way to see the result: C++ code

...

void AMyFirstGameCharacter::Tick(float DeltaTime)

{

Super::Tick(DeltaTime);

if (GEngine)

{

GEngine->AddOnScreenDebugMessage(-1, 0.0f, FColor::Blue,

FString::Printf(TEXT("Total Coins: %d"), TotalCoins));

}

...

First Game Tutorial

•

Quick way to see the result: C++ code for console debug

...

void AMyFirstGameCharacter::AddCoin()

{

TotalCoins++;

UE_LOG(LogTemp, Log, TEXT("Total Coins: %d"), TotalCoins);

}

...

First Game Tutorial

•

Displaying the information in the game UI with a Widget

Blueprint:

1. First, show total number of coins collected by the player;

2

. After collecting all coins in the level, show the message “All coins

collected!!!”.

•

Step 1: create a Widget Blueprint

First Game Tutorial

•

Step 2: instantiate the Widget Blueprint in the BeginPlay

event of the ThirdPersonCharacter blueprint.

First Game Tutorial

•

Step 3: create a method to count the number of coins in the

level (Game Mode class) and a variable to store the information.

private:

int CountCoinsInLevel();

MyFirstGameGameMode.h

...

protected:

UPROPERTY(BlueprintReadOnly, Category = "Gameplay")

int TotalLevelCoins;

AMyFirstGameGameMode::AMyFirstGameGameMode(){

MyFirstGameGameMode.cpp

...

TotalLevelCoins = CountCoinsInLevel();

}

int AMyFirstGameGameMode::CountCoinsInLevel(){

TArray<AActor*> FoundCoins;

UGameplayStatics::GetAllActorsOfClass(GetWorld(),

ACollectibleCoin::StaticClass(), FoundCoins);

return FoundCoins.Num();

}

First Game Tutorial

•

Step 4: bind the text value and create the Widget Blueprint

logic.

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

LevelCompleteArea.h

UCLASS()

class MYFIRSTGAME_API ALevelCompleteArea : public AActor

{

...

protected:

UPROPERTY(VisibleAnywhere, Category = "Components")

class UBoxComponent* BoxComponent;

UFUNCTION()

void HandleBeginOverlap(UPrimitiveComponent* OverlappedComponent,

AActor* OtherActor, UPrimitiveComponent* OtherComp,

int32 OtherBodyIndex, bool bFromSweep, const

FHitResult & SweepResult);

};

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

LevelCompleteArea.cpp

ALevelCompleteArea::ALevelCompleteArea()

{

BoxComponent = CreateDefaultSubobject<UBoxComponent>("BoxComponent");

BoxComponent->SetBoxExtent(FVector(200.0f, 200.0f, 200.0f));

BoxComponent->SetCollisionEnabled(ECollisionEnabled::QueryOnly);

BoxComponent->SetCollisionResponseToAllChannels(ECR_Ignore);

BoxComponent->SetCollisionResponseToChannel(ECC_Pawn, ECR_Overlap);

RootComponent = BoxComponent;

BoxComponent->OnComponentBeginOverlap.AddDynamic(this,

&ALevelCompleteArea::HandleBeginOverlap);

}

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

LevelCompleteArea.cpp

void ALevelCompleteArea::HandleBeginOverlap(UPrimitiveComponent*

OverlappedComponent, AActor* OtherActor,

UPrimitiveComponent* OtherComp, int32 OtherBodyIndex,

bool bFromSweep, const FHitResult & SweepResult){

AMyFirstGameCharacter* character = Cast<AMyFirstGameCharacter>

(

OtherActor);

AMyFirstGameGameMode* gamemode = Cast<AMyFirstGameGameMode>

GetWorld()->GetAuthGameMode());

(

if ((character)&& (gamemode)){

if (character->GetTotalCoins() == gamemode->GetTotalLevelCoins()){

gamemode->CompleteLevel(character, true);

}

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

public:

...

MyFirstGameGameMode.h

FORCEINLINE int GetTotalLevelCoins() const {return TotalLevelCoins;}

void CompleteLevel(APawn* character, bool succeeded);

UFUNCTION(BlueprintImplementableEvent, Category = "GameMode")

void OnLevelCompleted(APawn* character, bool succeeded);

...

MyFirstGameGameMode.cpp

void AMyFirstGameGameMode::CompleteLevel(APawn* character,

bool succeeded){

if (character){

character->DisableInput(nullptr);

}

OnLevelCompleted(character, succeeded);

}

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

1. Create a Widget Blueprint with a “Level Completed!” message;

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

2

. In the Widget, create a new boolean variable to represent succeeded value

and a blueprint to bind the correct message based on variable value;

First Game Tutorial

•

Level complete area: alter collecting all coins, the player

can go to this area to complete the level.

3

. Create a Blueprint for the Game Mode and instantiate the Widget in the

LevelCompleted event;

First Game Tutorial

•

Level complete area: if the player goes to the level complete

area without collecting all coins, a sound notification is played.

protected:

...

LevelCompleteArea.h

UPROPERTY(EditDefaultsOnly, Category = "Sounds")

USoundBase* LevelNotCompletedSound;

void ALevelCompleteArea::HandleBeginOverlap(...){

LevelCompleteArea.cpp

...

if ((character)&& (gamemode)){

if (character->GetTotalCoins() == gamemode->GetTotalLevelCoins()){

gamemode->CompleteLevel(character, true);

}

else{

UGameplayStatics::PlaySound2D(this, LevelNotCompletedSound);

}

First Game Tutorial

•

Moving the camera to a spectator viewpoint location after

completing the level:

1

. Create a blueprint class with a

camera (actor class);

2

. Place the camera in the

spectator viewpoint location;

First Game Tutorial

3. Move the camera to the spectator viewpoint: Blueprint solution

First Game Tutorial

. Move the camera to the spectator viewpoint: C++ solution

3

protected:

UPROPERTY(EditDefaultsOnly, Category = "Gameplay")

TSubclassOf<AActor> SpectatorViewpointClass;

MyFirstGameGameMode.h

void AMyFirstGameGameMode::CompleteLevel(APawn* character,

bool succeeded)){

if (character){

MyFirstGameGameMode.cpp

character->DisableInput(nullptr);

TArray<AActor*> foundViewpoints;

UGameplayStatics::GetAllActorsOfClass(GetWorld(),

SpectatorViewpointClass, foundViewpoints);

if (foundViewpoints.Num() > 0){

APlayerController* pController = Cast<APlayerController>

(character->GetController());

if (pController)

pController->SetViewTargetWithBlend(foundViewpoints[0], 0.8f);

}

OnLevelCompleted(character, true);

}

First Game Tutorial

•

Next step: create an enemy with AI that walks between

waypoints. When the enemy sees the player, he follows and

attacks the player.

–

Create new C++ class for the enemy: base class Character

–

Download and import the enemy model:

• http://www.inf.puc-rio.br/~elima/dp/zombie.zip

First Game Tutorial

•

Next step: create an enemy with AI.

–

Create and setup a blueprint for the new C++ enemy class:

First Game Tutorial

•

Next step: create an enemy with AI.

–

Add a Nav Mesh Bounds Volume and resize it so that it fits all of the

walkable space in the level:

First Game Tutorial

•

Next step: create an enemy with AI.

–

Place some waypoints (Target Point) in the level:

First Game Tutorial

•

Next step: create an enemy with AI.

...

EnemyCharacter.h

protected:

...

TArray<AActor*> Waypoints;

class AAIController* AIController;

TScriptDelegate<FWeakObjectPtr> MovementCompleteDelegate;

class ATargetPoint* GetRandomWaypoint();

UFUNCTION()

void AIMoveCompleted(FAIRequestID RequestID,

EPathFollowingResult::Type Result);

...

First Game Tutorial

•

Next step: create an enemy with AI.

#

include "Engine/TargetPoint.h"

include "AIController.h"

EnemyCharacter.cpp

void AEnemyCharacter::BeginPlay()

{

Super::BeginPlay();

UGameplayStatics::GetAllActorsOfClass(GetWorld(),

ATargetPoint::StaticClass(), Waypoints);

AIController = Cast<AAIController>(GetController());

this->bUseControllerRotationYaw = false;

if ((Waypoints.Num() > 0)&&(AIController)){

MovementCompleteDelegate.BindUFunction(this, "AIMoveCompleted");

AIController->ReceiveMoveCompleted.Add(MovementCompleteDelegate);

AIController->MoveToActor(GetRandomWaypoint());

}

First Game Tutorial

•

Next step: create an enemy with AI.

EnemyCharacter.cpp

ATargetPoint* AEnemyCharacter::GetRandomWaypoint()

{

int index = FMath::RandRange(0, Waypoints.Num() - 1);

return Cast<ATargetPoint>(Waypoints[index]);

}

void AEnemyCharacter::AIMoveCompleted(FAIRequestID RequestID,

EPathFollowingResult::Type Result){

if (Result == EPathFollowingResult::Success)

{

if ((Waypoints.Num() > 0) && (AIController))

{

AIController->MoveToActor(GetRandomWaypoint());

}

First Game Tutorial

•

Next step: create an enemy with AI.

–

Adjust max speed and rotation settings in the CharacterMovement

component:

First Game Tutorial

•

Next step: create an enemy with AI.

–

Add a SensingComponent to allow the enemy to see the player:

protected:

..

EnemyCharacter.h

.

UPROPERTY(VisibleAnywhere, Category = "Components")

class UPawnSensingComponent* SensingComponent;

AActor* target;

UFUNCTION()

void SeePlayer(APawn *pawn);

...

First Game Tutorial

•

Next step: create an enemy with AI.

–

Add a SensingComponent to allow the enemy to see the player:

AEnemyCharacter::AEnemyCharacter()

{

EnemyCharacter.cpp

SensingComponent = CreateDefaultSubobject<UPawnSensingComponent>

"SensingComponent");

(

SensingComponent->OnSeePawn.AddDynamic(this,

AEnemyCharacter::SeePlayer);

SensingComponent->SetSensingUpdatesEnabled(true);

&

}

void AEnemyCharacter::SeePlayer(APawn *pawn)

{

if ((pawn) && (AIController) && (!target)) {

target = pawn;

this->GetMesh()->GlobalAnimRateScale = 2.5f;

this->GetCharacterMovement()->MaxWalkSpeed = 150.0f;

AIController->MoveToActor(pawn);

}

First Game Tutorial

•

Next step: create an enemy with AI.

–

Add a SensingComponent to allow the enemy to see the player:

EnemyCharacter.cpp

void AEnemyCharacter::Tick(float DeltaTime)

{

Super::Tick(DeltaTime);

if (target)

{

if (FVector::Dist(GetActorLocation(), target->GetActorLocation())

>

SensingComponent->SightRadius)

{

}

this->GetMesh()->GlobalAnimRateScale = 1.0f;

this->GetCharacterMovement()->MaxWalkSpeed = 50;

target = nullptr;

AIController->MoveToActor(GetRandomWaypoint());

}

First Game Tutorial

•

Next step: create an enemy with AI.

–

Adjust the sight properties in the enemy blueprint:

First Game Tutorial

•

Next step: create an enemy with AI.

–

If the enemy gets to the player position, show the game over message:

void AEnemyCharacter::AIMoveCompleted(FAIRequestID RequestID,

EPathFollowingResult::Type Result){

if (Result == EPathFollowingResult::Success){

if (target){

AMyFirstGameCharacter* character = Cast<AMyFirstGameCharacter>

(

target);

AMyFirstGameGameMode* gamemode = Cast<AMyFirstGameGameMode>

GetWorld()->GetAuthGameMode());

(

if ((character) && (gamemode)){

gamemode->CompleteLevel(character, false);

}

target = nullptr;

}

if ((Waypoints.Num() > 0) && (AIController)){

AIController->MoveToActor(GetRandomWaypoint());

}

First Game Tutorial

•

Next step: create an enemy with AI.

–

If the player collides with the enemy, the enemy follows him:

UFUNCTION()

EnemyCharacter.h

void EnemyComponentHit(UPrimitiveComponent* HitComponent,

AActor* OtherActor, UPrimitiveComponent* OtherComp,

FVector NormalImpulse, const FHitResult& Hit);

void AEnemyCharacter::BeginPlay(){

Super::BeginPlay();

EnemyCharacter.cpp

GetCapsuleComponent()->OnComponentHit.AddDynamic(this,

&AEnemyCharacter::EnemyComponentHit);

...

}

void AEnemyCharacter::EnemyComponentHit(...)

{

SeePlayer(Cast<APawn>(OtherActor));

}

Exercise 1

1

) Finish the implementation of the game and balance the

gameplay.

a) Add more coins to the level;

b) Add more enemies to the level;

c) Add more waypoints to the level;

d) Adjust the position of the coins, enemies and waypoints;

e) Balance the speed of the enemies according to the speed of the

player;

f) Make the game more challenging and fun to play!