Spawning Actors - Access Violation Reading Location

Development Programming & Scripting C++
1

Hey, I am trying to spawn actors into my scene and my code was working before. But now I am recieiving a Access Violation Reading Location error.

TArray<FSpawnPosition> SpawnPositions = RandomSpawning(MinSpawn, MaxSpawn, Radius, 1.0f, 1.0f);
for (FSpawnPosition Spawn : SpawnPositions)
{
	APawn* Spawned = GetWorld()->SpawnActor<APawn>(ToSpawn);
	Spawned->SetActorRelativeLocation(FVector(0, 0, 500.0f));
	Spawned->AttachToActor(this, FAttachmentTransformRules(EAttachmentRule::KeepRelative, false));
	Spawned->SpawnDefaultController();
	Spawned->Tags.Add(FName("Enemy"));		
}

The debugger says its this line:
Spawned->AttachToActor(this, FAttachmentTransformRules(EAttachmentRule::KeepRelative, false));

I believe the APawn* Spawned is a nullptr, I am able to handle the error by an ensure statement. But now the spawning only works half the time

2

You can use deferred spawning to set transform properly.

3

Can you elaborate in that? I’m not sure what you mean? I have am using a debug sphere cast to make sure there are no other objects in the spawn point given.

EDIT: I see you were referring to the C++ function. I fixed my problem by offsetting the Spawn location.

4

Hi guys,

Deferred spawning give you the opportunity to set variables before spawn your instance inside the world, for example mark an UPROPERTY with meta expose on spawn, but I think is not your case, indeed, apparently your APawn* is nullptr, just verify that with a simple if(Spawned ) before call anything else, your problem is your spawn, World()->SpawnActor<APawn>(APawn::StaticClass(),FTransform, FActorSpawnParameters), this is the most common way, but you have like seven overrides for SpawnActor template method inside UWorld class

5

The Spawning is failing periodically because of encroaching geometry. If you want to force the actor to spawn regardless of collision, you need to pass the proper parameters into SpawnActor():



	FActorSpawnParameters SpawnParams = FActorSpawnParameters();
	SpawnParams.SpawnCollisionHandlingOverride = ESpawnActorCollisionHandlingMethod::AdjustIfPossibleButAlwaysSpawn;

	GetWorld()->SpawnActor(MyActor, SpawnParams);

There are a few different options for ESpawnActorCollisionHandlingMethod

Deferred Spawning requires the same parameters.

6

Thanks for the responses everyone, I will try to implement some of this to my code