Description

This is a semi-common crash that has occurred since at least 4.17.1. The callstack is nearly identical to [Link Removed], which was fixed in 4.18.0, however the error message and source context are different. Users have not provided any descriptions of their actions when the crash occurred.

Edit, this may actually be a continuation of [Link Removed], but I've gone ahead and closed that one out.

Source Context

 673       		if (IndexBuffer != nullptr && IndexBuffer->Indices.Num() >= 0)
  674       		{
  675       			IndexBufferSize = IndexBuffer->Indices.Num();
  676       
  677       			for (uint32 TriIdx = 0; TriIdx < Element.NumTriangles; TriIdx++)
  678       			{
  679       				FTriIndices Triangle;
  680       
  681       				Triangle.v0 = IndexBuffer->Indices[Element.FirstIndex + (TriIdx * 3) + 0];
  682       				Triangle.v1 = IndexBuffer->Indices[Element.FirstIndex + (TriIdx * 3) + 1];
  683       				Triangle.v2 = IndexBuffer->Indices[Element.FirstIndex + (TriIdx * 3) + 2];
  684       
  685       				if (AreaThreshold >= 0.f)
  686       				{
  687 ***** 					const FVector V0 = Model->VertexBuffer.Vertices[Triangle.v0].Position;
  688       					const FVector V1 = Model->VertexBuffer.Vertices[Triangle.v1].Position;
  689       					const FVector V2 = Model->VertexBuffer.Vertices[Triangle.v2].Position;
  690       
  691       					const FVector V01 = (V1 - V0);
  692       					const FVector V02 = (V2 - V0);
  693       					const FVector Cross = FVector::CrossProduct(V01, V02);
  694       					const float Area = Cross.Size() * 0.5f;
  695       					if (Area <= AreaThreshold)
  696       					{
  697       						nBadArea++;
  698       						continue;
  699       					}
  700       				}
Steps to Reproduce

repro steps currently unknown

Callstack
Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build\++UE4+Release-4.18+Compile\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 610] 
Array index out of bounds: 1136059356 from an array of size 1624

UE4Editor_Engine!UModelComponent::GetPhysicsTriMeshData() [modelcomponent.cpp:688]
UE4Editor_Engine!UBodySetup::GetCookInfo() [bodysetup.cpp:285]
UE4Editor_Engine!FDerivedDataPhysXCooker::Build() [physderiveddata.cpp:93]
UE4Editor_DerivedDataCache!FDerivedDataCache::FBuildAsyncWorker::DoWork() [deriveddatacache.cpp:186]
UE4Editor_DerivedDataCache!FAsyncTask<FDerivedDataCache::FBuildAsyncWorker>::DoWork() [asyncwork.h:264]
UE4Editor_DerivedDataCache!FAsyncTask<FDerivedDataCache::FBuildAsyncWorker>::Start() [asyncwork.h:252]
UE4Editor_DerivedDataCache!FDerivedDataCache::GetSynchronous() [deriveddatacache.cpp:263]
UE4Editor_Engine!UBodySetup::GetCookedData() [bodysetup.cpp:1455]
UE4Editor_Engine!UBodySetup::BeginCacheForCookedPlatformData() [bodysetup.cpp:1356]
UE4Editor_UnrealEd!UCookOnTheFlyServer::FinishPackageCacheForCookedPlatformData() [cookontheflyserver.cpp:1929]
UE4Editor_UnrealEd!UCookOnTheFlyServer::SaveCookedPackages() [cookontheflyserver.cpp:2195]
UE4Editor_UnrealEd!UCookOnTheFlyServer::TickCookOnTheSide() [cookontheflyserver.cpp:1763]
UE4Editor_UnrealEd!UCookOnTheFlyServer::Tick() [cookontheflyserver.cpp:877]
UE4Editor_UnrealEd!FTickableEditorObject::TickObjects() [tickableeditorobject.h:21]
UE4Editor_UnrealEd!UEditorEngine::Tick() [editorengine.cpp:1433]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [unrealedengine.cpp:396]
UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3296]
UE4Editor!GuardedMain() [launch.cpp:166]
UE4Editor!GuardedMainWrapper() [launchwindows.cpp:134]
UE4Editor!WinMain() [launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [exe_common.inl:253]
kernel32!BaseThreadInitThunk()
ntdll!RtlUserThreadStart()

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Fixed
ComponentUE - Simulation - Physics
Affects Versions4.174.18
Target Fix4.18.1
Fix Commit3677306
CreatedOct 30, 2017
ResolvedOct 31, 2017
UpdatedApr 27, 2018