Spawning a simple cube

Development Programming & Scripting C++
1

Hi,

I can’t believe help is so scarce for something so simple.

I want to spawn a cube at a location, and I’d also like to know how to set its scale and rotation should they be required in the future.

What I’ve gathered, probably full of errors:

.cpp:



ASpawnableCube::ASpawnableCube()
{ 	
	TSubobjectPtr<UBoxComponent> Box;

	Box = ObjectInitializer.CreateDefaultSubobject<USkeletalMeshComponent>(this, TEXT("SpookyBox"));
	Box->bHiddenInGame = false;
	 = Box;
	MeshLocation = FVector(someX, someY, someZ);
}

void ASpawnableCube::BeginPlay()
{
	Super::BeginPlay();
	UE_LOG(LogTemp, Error, TEXT("CUBE SPAWNED"));
}
2

So there’s a number of issues with your code you provided:

  • I don’t recommend having the mesh the root of the object, you should be using a USceneComponent. Reason I recommend this is that it’s good practice for objects that require multiple meshes; a root USceneComponent allow you to transform every object under it at once without the need for a physical representation of said root.
  • You declared Box in the scope of your constructor which goes out of scope the moment the object is constructed which will likely cause UE4 to either crash or the mesh to be GC’d.
  • As for rotation and scale, USkeletalMeshComponent and UBoxComponent are children of USceneComponent which contains the SetRelativeScale3D & SetWorldScale3D methods required for scaling and the relative methods for rotation.

I highly recommend reading through the UE4 docs, even if it’s just skim reading because it’s more than likely the pages on there contain some very good example code that could help you in the future. Before exclaiming “Help is so scarce”, unless you live in China, help is not scarce on the World Wide Web: a quick Google of “ue4 spawn cube c++” gave me this link as the first answer which suggests to call ‘GetWorld()->SpawnActor(ACube::StaticClass());’.

3

Btw, not sure why you haven’t followed any tutorial/guide for beginners, you are also using deprecated code

4

I would start with something like:

.h]


#pragma once

#include "GameFramework/Actor.h"
#include "BoxActor.generated.h"

UCLASS()
class MYGAME_API ABoxActor : public AActor
{
    GENERATED_BODY()
	
public:	
    ABoxActor();
    virtual void BeginPlay() override;
    virtual void Tick( float DeltaTime );	
    
    UPROPERTY( BlueprintReadOnly, VisibleAnywhere, Category = "Mesh" )
    UStaticMeshComponent *MeshComp;    
};

.cpp]


#include "MyGame.h"
#include "BoxActor.h"

ABoxActor::ABoxActor( )
{
    PrimaryActorTick.bCanEverTick = true;

    MeshComp = CreateDefaultSubobject<UStaticMeshComponent>( TEXT("Mesh") );
     = MeshComp;
}

void ABoxActor::BeginPlay( )
{
    Super::BeginPlay( );
}

void ABoxActor::Tick(float DeltaTime)
{
    Super::Tick(DeltaTime);
}