Hello, help a newbie understand the basics. In a new project, I created two C++ classes: Cube and MyPawn.
Cube.cpp
// Sets default values
ACube::ACube()
{
// Set this pawn to call Tick() every frame. You can turn this off to improve performance if you dont need it.
PrimaryActorTick.bCanEverTick = true;
static ConstructorHelpers::FObjectFinder<UStaticMesh>C(TEXT("StaticMesh'/Game/StarterContent/Shapes/Shape_Cube.Shape_Cube'"));
UStaticMeshComponent* Cube = CreateDefaultSubobject<UStaticMeshComponent>("Cube");
Cube->SetupAttachment(RootComponent);
Cube->SetWorldScale3D(FVector(0.1f));
Cube->SetStaticMesh(C.Object);
}
Your ActorsToIgnore is empty. You either need to spawn the actors up front to an array or during the iteration add the middle element to the ActorsToIgnore array (it can’t be const because it needs to change at runtime)
Okay, but how can I write into an array cell with
specific index? This code throws an error.
if (i == 1) ActorsToIgnore[0] = MyCube[i];
And a few more questions.
I can write the LineTraceSingle function this way.
Cube.cpp
// Called when the game starts or when spawned
void ACube::BeginPlay()
{
Super::BeginPlay();
ETraceTypeQuery TraceChannel = UEngineTypes::ConvertToTraceType(ECollisionChannel::ECC_Visibility);
TArray<AActor*> ActorsToIgnore;
FHitResult HitResult;
FVector start = GetActorLocation();
start.Z = 100.f;
FVector stop = start;
stop.Z = 0.f;
UKismetSystemLibrary::LineTraceSingle(GetWorld(), start, stop, TraceChannel, false,
ActorsToIgnore, EDrawDebugTrace::ForDuration, HitResult, true, FColor::Red, FColor::Green, 500.f);
}
MyPawn.cpp
// Called when the game starts or when spawned
void AMyPawn::BeginPlay()
{
Super::BeginPlay();
ACube* MyCube[3];
for (int i = 0; i <= 2; i++)
{
MyCube[i] = GetWorld()->SpawnActor<ACube>(FVector(0.f + i * 15.f, 150.f, 70.f), FRotator(0.f));
}
}
How can I ignore all the cubes in this case?
How to ignore only the middle cube?
ActorsToIgnore starts out empty. You cannot just go and reference ActorsToIgnore[0] as that part of the array is not initialized. It probably throws an out of bounds exception right?
valid_index_in_MyCube_array will choose which one of the elements passes through.
0 => first added element
1 => second added element
2 => third added element
ActorsToIgnore.Add(MyCube[valid_index_in_MyCube_array]); on the other hand will expand the ActorsToIgnore array by 1 new element, in this case adding to it and element from the MyCube array.
You can go into arrays blindly, you have to for instance do checks like ActorsToIgnore.Num() to get the amount of elements in the array to see where the upper limit of the array is.
Notice that when you wrote ACube* MyCube[3]; you initialized it with 3 elements. There is no equvalant done for ActorsToIgnore. You could set a predefined limit if you knew up front how many ignores you need, then you could use direct access like [0] , [1], [2] as long as the chosen index is within the arrays length (remember arrays start from 0 so always count -1 with indexes)
