Hard crash using FVectors

[Travis.D]

So I have a race type thing, where the camera is out the front looking back down the track at the racers. I want it to look at the leader, so this is a function I wrote to check for which racer is closest to the camera and return its location. It does this every tick, which seems expensive? But I don’t know a better way keep track of who the leader is.

FVector ATrack::GetLeaderLocation()
{
    float ClosestThisTick = 0.f;
    FVector ClosestLocation;
    FVector CameraLocation = Camera->GetComponentLocation();
    for (ARacer* Racer : AllRacers)
    {
        FVector RacerLocation = Racer->GetActorLocation();
        float RacerDist = (CameraLocation - RacerLocation).Size();
        if (RacerDist > ClosestThisTick)
        {
            ClosestThisTick = RacerDist;
            ClosestLocation = RacerLocation;
        }
    }
    return ClosestLocation;
}

When I attach the Visual Studio debugger to the process, it’s showing that it locks up here:

UnrealMathSSE.h

Any ideas what the problem is? Or if there’s a better way to say “Who’s winning and where are you?”

Cheers

[TacoShank]

So to really be of any help we’d need a full stack trace. You triggered the break point pretty deep in UE4 engine code. But if I had to take a crack at it with this little info I’d say it looks like some kind of problem with the pointers you’re accessing. From what I can tell VectorStoreFloat3 is related to FVector assignment, and there are multiple places where you assign FVectors in the code you provided.

FVector ATrack::GetLeaderLocation()
{
    float ClosestThisTick = 0. f;
    FVector ClosestLocation;
    F**Vector CameraLocation = Camera - > GetComponentLocation();**
    for (ARacer * Racer: AllRacers)
    {
        F**Vector RacerLocation = Racer - > GetActorLocation();**
        float RacerDist = (CameraLocation - RacerLocation).Size();
        if (RacerDist > ClosestThisTick)
        {
            ClosestThisTick = RacerDist;
            ClosestLocation = RacerLocation;
        }
    }
    return ClosestLocation;
}

For a start (assuming the stack trace even leads back to this code snippet) I’d double check what’s happening with the two lines I marked in bold. Consider stepping through the code with a debugger to observe if there are any problems here and figure out exactly what part of your code is causing the bug because it most likely is not an engine bug.