Add ToggleLight class to trigger lights in radius

+ Followed UE4 tutoial on mixing C++ and Blueprints
+ https://docs.unrealengine.com/4.27/en-US/ProgrammingAndScripting/ClassCreation/CodeAndBlueprints/
+ Added an in-editor and blueprint field ToggleLight::Radius to adjust
  trigger radius
+ Made stairs light up as you walk up them

Source/ThirdPerson/Private/ToggleLight.cpp

@@ -0,0 +1,59 @@
+// All content (c) Shaun Reed 2021, all rights reserved
+
+
+#include "ToggleLight.h"
+
+#include "Components/PointLightComponent.h"
+#include "Components/SphereComponent.h" 
+
+// Sets default values
+AToggleLight::AToggleLight()
+{
+ 	// Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
+	PrimaryActorTick.bCanEverTick = true;
+
+  DesiredIntensity = 3000.0f;
+
+  PointLight1 = CreateDefaultSubobject<UPointLightComponent>(TEXT("PointLight1"));
+  PointLight1->Intensity = DesiredIntensity;
+  // PointLight1->bVisible = true;
+  RootComponent = PointLight1;
+
+  Sphere1 = CreateDefaultSubobject<USphereComponent>(TEXT("Sphere1"));
+  Sphere1->InitSphereRadius(Radius);
+  Sphere1->SetupAttachment(RootComponent);
+
+  Sphere1->OnComponentBeginOverlap.AddDynamic(this, &AToggleLight::OnOverlapBegin);       // set up a notification for when this component overlaps something
+  Sphere1->OnComponentEndOverlap.AddDynamic(this, &AToggleLight::OnOverlapEnd);       // set up a notification for when this component overlaps something
+}
+
+void AToggleLight::OnOverlapBegin_Implementation(UPrimitiveComponent* OverlappedComp, AActor* OtherActor, UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult) 
+{
+  if (OtherActor && (OtherActor != this) && OtherComp)
+  {
+    ToggleLight();
+  }
+}
+
+void AToggleLight::OnOverlapEnd_Implementation(UPrimitiveComponent* OverlappedComp, AActor* OtherActor, UPrimitiveComponent* OtherComp, int32 OtherBodyIndex)
+{
+  if (OtherActor && (OtherActor != this) && OtherComp)
+  {
+    ToggleLight();
+  }
+}
+
+void AToggleLight::ToggleLight()
+{
+  PointLight1->ToggleVisibility();
+}
+
+void AToggleLight::Tick(float DeltaTime)
+{
+  if (Radius != Sphere1->GetUnscaledSphereRadius())
+  {
+    Sphere1->SetSphereRadius(Radius);
+  }
+
+}
+

Source/ThirdPerson/Public/ToggleLight.h

@@ -0,0 +1,53 @@
+// All content (c) Shaun Reed 2021, all rights reserved
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "GameFramework/Actor.h"
+#include "ToggleLight.generated.h"
+
+UCLASS()
+class THIRDPERSON_API AToggleLight : public AActor
+{
+  GENERATED_BODY()
+
+public:
+  // Sets default values for this actor's properties
+  AToggleLight();
+
+  UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Switch Components")
+    class UPointLightComponent* PointLight1;
+
+  UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "Switch Components")
+    class USphereComponent* Sphere1;
+
+  // Radius of the trigger to toggle the light
+  UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Switch Variables")
+    float Radius = 50.0f;
+
+  /** the desired intensity for the light */
+  UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Switch Variables")
+    float DesiredIntensity;
+
+  /** Toggles the light component's visibility*/
+  UFUNCTION()
+    void ToggleLight();
+  
+  //
+  // Trigger functions
+
+  /** called when something enters the sphere component */
+  UFUNCTION(BlueprintNativeEvent, Category = "Switch Functions")
+    void OnOverlapBegin(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult);
+  void OnOverlapBegin_Implementation(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex, bool bFromSweep, const FHitResult& SweepResult);
+
+  /** called when something leaves the sphere component */
+  UFUNCTION(BlueprintNativeEvent, Category = "Switch Functions")
+    void OnOverlapEnd(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex);
+  void OnOverlapEnd_Implementation(class UPrimitiveComponent* OverlappedComp, class AActor* OtherActor, class UPrimitiveComponent* OtherComp, int32 OtherBodyIndex);
+
+  //
+  // Update functions
+
+  virtual void Tick(float DeltaTime) override;
+};