it may be instance data can not update at 1st frame when UHierarchicalInstancedStaticMeshComponent is created, I print log in actor “beginPlay” and actor "tick "
// Called when the game starts or when spawned
void AMyActor::BeginPlay()
{
Super::BeginPlay();
UWorld* const World = GetWorld(); // Get world
if (!World) return;
// Just prep
FVector spawnLocation = FVector(0.f, 0.f, 0.f);
FRotator rotator = FRotator(0.f, 0.f, 0.f);
FActorSpawnParameters spawnParams;
FTransform InstanceTransform;
InstanceTransform.SetLocation(FVector::ZeroVector);
InstanceTransform.SetRotation(FQuat::Identity);
InstanceTransform.SetScale3D(FVector(1., 1., 1.));
host = World->SpawnActor<AActor>(spawnLocation, rotator, spawnParams);
host->SetActorEnableCollision(true);
// Create HISM component
MyTestCpt = NewObject<UHierarchicalInstancedStaticMeshComponent>(host);
MyTestCpt->RegisterComponent();
MyTestCpt->SetStaticMesh(MyStaticMesh);
host->AddInstanceComponent(MyTestCpt);
// Add three instances, near the origin.
InstanceTransform.SetLocation(FVector(0., 0., 0.));
MyTestCpt->AddInstance(InstanceTransform);
InstanceTransform.SetLocation(FVector(10., 10., 10.));
MyTestCpt->AddInstance(InstanceTransform);
InstanceTransform.SetLocation(FVector(-10., -10., -10.));
MyTestCpt->AddInstance(InstanceTransform);
// Now we try and find them
TArray<int32> ids = MyTestCpt->GetInstancesOverlappingSphere(FVector(0., 0., 0.), 100., true);
UE_LOG(LogTemp, Warning, TEXT("Begin play ---Found %i HISMS"), ids.Num());
}
// Called every frame
void AMyActor::Tick(float DeltaTime)
{
Super::Tick(DeltaTime);
if (MyTestCpt != nullptr)
{
// Now we try and find them
TArray<int32> ids = MyTestCpt->GetInstancesOverlappingSphere(FVector(0., 0., 0.), 100., true);
UE_LOG(LogTemp, Warning, TEXT("Tick Found %i HISMS"), ids.Num());
}
}
you can call UHierarchicalInstancedStaticMeshComponent API -----BuildTreeIfOutdated,refrersh data at once
MyTestCpt->BuildTreeIfOutdated(false, true);
