Section 15: AI and Behavior Trees - Lecture 284

Stunned Blackboard Decorator

Source/Shooter/Enemy.cpp

@@ -11,6 +11,8 @@
 #include "DrawDebugHelpers.h"
 #include "EnemyController.h"
 #include "BehaviorTree/BlackboardComponent.h"
+#include "Components/SphereComponent.h"
+#include "ShooterCharacter.h"
 
 // Sets default values
 AEnemy::AEnemy() :
@@ -20,10 +22,16 @@ AEnemy::AEnemy() :
 	HitReactTimeMin(.5f),
 	HitReactTimeMax(1.f),
 	bCanHitReact(true),
-	HitNumberDestroyTime(1.5f)
+	HitNumberDestroyTime(1.5f),
+	bStunned(false),
+	StunChance(.5f)
 {
  	// Set this character to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
 	PrimaryActorTick.bCanEverTick = true;
+
+	// Create the Agro Sphere
+	AgroSphere = CreateDefaultSubobject<USphereComponent>(TEXT("AgroSphere"));
+	AgroSphere->SetupAttachment(GetRootComponent());
 }
 
 // Called when the game starts or when spawned
@@ -31,6 +39,8 @@ void AEnemy::BeginPlay()
 {
 	Super::BeginPlay();
 
+	AgroSphere->OnComponentBeginOverlap.AddDynamic(this, &AEnemy::AgroSphereOverlap);
+	
 	GetMesh()->SetCollisionResponseToChannel(ECollisionChannel::ECC_Visibility, ECollisionResponse::ECR_Block);
 
 	// Get the AI Controller
@@ -39,12 +49,15 @@ void AEnemy::BeginPlay()
 	const FVector WorldPatrolPoint = UKismetMathLibrary::TransformLocation(GetActorTransform(), PatrolPoint);
 	DrawDebugSphere(GetWorld(), WorldPatrolPoint, 25.f, 12, FColor::Red, true);
 
+	const FVector WorldPatrolPoint2 = UKismetMathLibrary::TransformLocation(GetActorTransform(), PatrolPoint2);
+	DrawDebugSphere(GetWorld(), WorldPatrolPoint2, 25.f, 12, FColor::Blue, true);
+	
 	if (EnemyController)
 	{
 		EnemyController->GetBlackboardComponent()->SetValueAsVector("PatrolPoint", WorldPatrolPoint);
+		EnemyController->GetBlackboardComponent()->SetValueAsVector("PatrolPoint2", WorldPatrolPoint2);
 		EnemyController->RunBehaviorTree(BehaviorTree);
 	}
-	
 }
 
 void AEnemy::ShowHealthBar_Implementation()
@@ -108,6 +121,25 @@ void AEnemy::UpdateHitNumbers()
 	}
 }
 
+void AEnemy::AgroSphereOverlap(UPrimitiveComponent* OverlappedComponent, AActor* OtherActor,
+	UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult)
+{
+	if (!OtherActor) return;
+	auto Character = Cast<AShooterCharacter>(OtherActor);
+	if (!Character) return;
+
+	// Set the value of the Target blackboard key
+	EnemyController->GetBlackboardComponent()->SetValueAsObject(TEXT("Target"), Character);
+}
+
+void AEnemy::SetStunned(bool Stunned)
+{
+	bStunned = Stunned;
+
+	if (!EnemyController) return;
+	EnemyController->GetBlackboardComponent()->SetValueAsBool(TEXT("Stunned"), Stunned);
+}
+
 // Called every frame
 void AEnemy::Tick(float DeltaTime)
 {
@@ -137,7 +169,14 @@ void AEnemy::BulletHit_Implementation(FHitResult HitResult)
 	
 	ShowHealthBar();
 
-	PlayHitMontage(FName("HitReactFront"));
+	// Determine whether bullet hit stuns
+	const float Stunned = FMath::FRandRange(0.f, 1.f);
+	if (Stunned <= StunChance)
+	{
+		// Stun the Enemy
+		PlayHitMontage(FName("HitReactFront"));
+		SetStunned(true);
+	}
 }
 
 float AEnemy::TakeDamage(float DamageAmount, FDamageEvent const& DamageEvent, AController* EventInstigator,

Source/Shooter/Enemy.h

@@ -12,6 +12,7 @@ class USoundCue;
 class UAnimMontage;
 class UBehaviorTree;
 class AEnemyController;
+class USphereComponent;
 
 UCLASS()
 class SHOOTER_API AEnemy : public ACharacter, public IBulletHitInterface
@@ -46,6 +47,15 @@ protected:
 	void DestroyHitNumber(UUserWidget* HitNumber);
 
 	void UpdateHitNumbers();
+
+	/** Called when something overlaps with the agro sphere */
+	UFUNCTION()
+	void AgroSphereOverlap(UPrimitiveComponent* OverlappedComponent, AActor* OtherActor,
+		UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep,
+		const FHitResult& SweepResult);
+
+	UFUNCTION(BlueprintCallable)
+	void SetStunned(bool Stunned);
 private:
 	/** Particles to spawn when hit by bullets */
 	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Combat, meta = (AllowPrivateAccess = true))
@@ -102,7 +112,23 @@ private:
 	UPROPERTY(EditAnywhere, Category = "Behavior Tree", meta = (AllowPrivateAccess = true, MakeEditWidget = true))
 	FVector PatrolPoint;
 
+	/** 2nd Point for the enemy to move to */
+	UPROPERTY(EditAnywhere, Category = "Behavior Tree", meta = (AllowPrivateAccess = true, MakeEditWidget = true))
+	FVector PatrolPoint2;
+	
 	AEnemyController* EnemyController;
+
+	/** Overlap sphere for when the enemy becomes hostile */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Behavior Tree", meta = (AllowPrivateAccess = true))
+	USphereComponent* AgroSphere;
+
+	/** True when playing the get hit animation */
+	UPROPERTY(VisibleAnywhere, BlueprintReadWrite, Category = Combat, meta = (AllowPrivateAccess = true))
+	bool bStunned;
+
+	/** Chance of being stunned. 0: no stun chance, 1: 100% stun chance */
+	UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = Combat, meta = (AllowPrivateAccess = true))
+	float StunChance;
 public:	
 	// Called every frame
 	virtual void Tick(float DeltaTime) override;

Source/Shooter/GruxAnimInstance.cpp

@@ -3,3 +3,17 @@
 
 #include "GruxAnimInstance.h"
 
+#include "Enemy.h"
+
+void UGruxAnimInstance::UpdateAnimationProperties(float DeltaTime)
+{
+	if (!Enemy)
+	{
+		Enemy = Cast<AEnemy>(TryGetPawnOwner());
+		if (!Enemy) return;
+	}
+
+	FVector Velocity { Enemy->GetVelocity() };
+	Velocity.Z = 0.f;
+	Speed = Velocity.Size();
+}

Source/Shooter/GruxAnimInstance.h

@@ -6,6 +6,8 @@
 #include "Animation/AnimInstance.h"
 #include "GruxAnimInstance.generated.h"
 
+class AEnemy;
+
 /**
  * 
  */
@@ -14,4 +16,15 @@ class SHOOTER_API UGruxAnimInstance : public UAnimInstance
 {
 	GENERATED_BODY()
 
+public:
+		
+	UFUNCTION(BlueprintCallable)
+	void UpdateAnimationProperties(float DeltaTime);
+private:
+	/** Lateral Movement Speed */
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = Movement, meta = (AllowPrivateAccess = true))
+	float Speed;
+
+	UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (AllowPrivateAccess = true))
+	AEnemy* Enemy;
 };