Hello everyone,
I’ve recently started with UE4 and today was the fist time I tried working with construction scripts and static meshes instances. But now UE4 crashes whenever I compile my C++ derived Blueprint.
The goal is to make the same procedural generation as the one in this tutorial video : Unreal Engine 4 - Procedural Generation Ladder - YouTube
Here is my OnConstruction call :
void ALadder::OnConstruction(const FTransform &Transform)
{
Super::OnConstruction(Transform);
// Do some clean up first
for (int i = 0; i < LadderStraight->GetInstanceCount(); i++) {
LadderStraight->RemoveInstance(i);
}
for (int i = 0; i < LadderAttach->GetInstanceCount(); i++) {
LadderAttach->RemoveInstance(i);
}
for (int i = 0; i < LadderBottom->GetInstanceCount(); i++) {
LadderBottom->RemoveInstance(i);
}
for (int i = 0; i < LadderTop->GetInstanceCount(); i++) {
LadderTop->RemoveInstance(i);
}
// Now we start the real construction
for (int i = 0; i < AmountLadderMeshes; i++)
{
if (i == 0) {
LadderBottom->AddInstance(FTransform(FVector(0, 0, i*MeshHeight)));
}
else if (i == AmountLadderMeshes - 1) {
LadderTop->AddInstance(FTransform(FVector(0, 0, i*MeshHeight)));
}
else if (i % 3 == 0) {
LadderAttach->AddInstance(FTransform(FVector(0, 0, i*MeshHeight)));
}
else {
LadderStraight->AddInstance(FTransform(FVector(0, 0, i*MeshHeight)));
}
}
}
I’ve tried removing the second for loop and the crashing stops.
I’ve also tried making the same visual script as on the video but the crashing still occurs. 
So I thought that maybe it’s the UInstancedStaticMeshComponent objects. But I have no idea if it can be them, anyway here is how I make them in the class constructor. Just in case.
// Setup the meshes
LadderStraight = CreateAbstractDefaultSubobject<UInstancedStaticMeshComponent>(TEXT("LadderStraight"));
ConstructorHelpers::FObjectFinder<UStaticMesh> mesh(TEXT("StaticMesh'/Game/Meshes/Ladder_Straight.Ladder_Straight'"));
if (mesh.Succeeded()) {
LadderStraight->SetStaticMesh(mesh.Object);
}
LadderAttach = CreateAbstractDefaultSubobject<UInstancedStaticMeshComponent>(TEXT("LadderAttach"));
mesh = ConstructorHelpers::FObjectFinder<UStaticMesh>(TEXT("StaticMesh'/Game/Meshes/Ladder_Attach.Ladder_Attach'"));
if (mesh.Succeeded()) {
LadderAttach->SetStaticMesh(mesh.Object);
}
LadderTop = CreateAbstractDefaultSubobject<UInstancedStaticMeshComponent>(TEXT("LadderTop"));
mesh = ConstructorHelpers::FObjectFinder<UStaticMesh>(TEXT("StaticMesh'/Game/Meshes/Ladder_Top.Ladder_Top'"));
if (mesh.Succeeded()) {
LadderTop->SetStaticMesh(mesh.Object);
}
LadderBottom = CreateAbstractDefaultSubobject<UInstancedStaticMeshComponent>(TEXT("LadderBottom"));
mesh = ConstructorHelpers::FObjectFinder<UStaticMesh>(TEXT("StaticMesh'/Game/Meshes/Ladder_Bottom.Ladder_Bottom'"));
if (mesh.Succeeded()) {
LadderBottom->SetStaticMesh(mesh.Object);
}