I am continuing the Battery Collector in C++ tutorial from Unreal Engine. This is the 6th video.

We will create a Spawning Volume with functionalities to setup:

• Where to Spawn
• What to Spawn
• When to Spawn

There are 3 videos for each functionality.

Creating a Spawning Volume

Before going on, I delete the pickups in the level. Then I create a new C++ class based on Actor and named SpawnVolume:

In the SpawnVolume.h file, I add a UBoxComponent pointer named WhereToSpawn:

private:
 /** Box Component to specify where pickups should be spawned */
 UPROPERTY(VisibleAnyWhere, BlueprintReadOnly, Category = "Spawning", meta = (AllowPrivateAccess = "true"))
 class UBoxComponent* WhereToSpawn;

In the public section, I add an accessor function:

/** Returns the WhereToSpawn subobject */
FORCEINLINE class UBoxComponent* GetWhereToSpawn() const { return WhereToSpawn; }

Note: in the Pickup.h file, we didn’t use a FORCEINLINE macro for IsActive() because BlueprintPure functions are not compatible with inline macros.

In the constructor of SpawnVolume.cpp, I create the box and set it as the RootComponent:

// Create the Box Component to represent the spawn volume
 WhereToSpawn = CreateDefaultSubobject<UBoxComponent>(TEXT("WhereToSpawn"));
 RootComponent = WhereToSpawn;

In that constructor, I also disable the call to Tick() every frame:

PrimaryActorTick.bCanEverTick = false;

Back to the header file, I declare a GetRandomPointInVolume public function:

 /** Find a random point within the BoxComponent */
 UFUNCTION(BlueprintPure, Category = "Spawning")
 FVector GetRandomPointInVolume();

In the source file, I include the KismetMathLibrary to get access to random math functions:

#include "Kismet/KismetMathLibrary.h"

Then I create the GetRandomPointInVolume definition:

FVector ASpawnVolume::GetRandomPointInVolume()
{
 FVector SpawnOrigin = WhereToSpawn->Bounds.Origin;
 FVector SpawnExtent = WhereToSpawn->Bounds.BoxExtent;
 
 return UKismetMathLibrary::RandomPointInBoundingBox(SpawnOrigin, SpawnExtent);
}

Instead of compiling in Unreal Engine editor, I can build in Visual Studio:

Next Step

In the next step, we will define what to spawn.