Description

This is a semi-common crash in the 4.18 release. There is one recorded case of this callstack also occurring back in the 4.11 release, but it seems to be an exception. All other cases have only occurred in the 4.18 release.

User Descriptions

  • painting the landscape

Source Context

 2292       	ALandscapeProxy* Proxy = Component->GetLandscapeProxy();
 2293       	Component->Modify();
 2294       	Proxy->Modify();
 2295       
 2296       	// Mark the channel as unallocated, so we can reuse it later
 2297       	const int32 DeleteLayerWeightmapTextureIndex = Component->WeightmapLayerAllocations[LayerIdx].WeightmapTextureIndex;
 2298       	FLandscapeWeightmapUsage& Usage = Proxy->WeightmapUsageMap.FindChecked(Component->WeightmapTextures[DeleteLayerWeightmapTextureIndex]);
 2299 ***** 	Usage.ChannelUsage[Component->WeightmapLayerAllocations[LayerIdx].WeightmapTextureChannel] = NULL;
 2300       
 2301       	// Remove the layer as it's totally painted away.
 2302       	Component->WeightmapLayerAllocations.RemoveAt(LayerIdx);
Steps to Reproduce

repro steps currently unknown

 

Callstack
Assertion failed: Pair != nullptr [File:D:\Build\++UE4+Release-4.18+Compile\Sync\Engine\Source\Runtime\Core\Public\Containers/Map.h] [Line: 478]

UE4Editor_Landscape!DeleteLayerIfAllZero() [landscapeeditinterface.cpp:2300]
UE4Editor_Landscape!FLandscapeEditDataInterface::SetAlphaData() [landscapeeditinterface.cpp:2916]
UE4Editor_LandscapeEditor!FAlphamapAccessor<1,0>::SetData() [landscapeedmodetools.h:968]
UE4Editor_LandscapeEditor!FLandscapeToolStrokePaint::Apply() [landscapeedmodepainttools.cpp:253]
UE4Editor_LandscapeEditor!FLandscapeToolBase<FLandscapeToolStrokePaint>::Tick() [landscapeedmodetools.h:1353]
UE4Editor_LandscapeEditor!FEdModeLandscape::Tick() [landscapeedmode.cpp:737]
UE4Editor_UnrealEd!FEditorModeTools::Tick() [editormodemanager.cpp:716]
UE4Editor_UnrealEd!FLevelEditorViewportClient::Tick() [leveleditorviewport.cpp:2072]
UE4Editor_UnrealEd!UEditorEngine::Tick() [editorengine.cpp:1734]
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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Cannot Reproduce
ComponentUE - LD & Modeling - Terrain - Landscape
Affects Versions4.184.18.14.19
Target Fix4.21
CreatedNov 28, 2017
ResolvedOct 22, 2018
UpdatedDec 11, 2018