4.5 Lightmap UV generator error

Development Platform & Builds
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1

Hi,

I am getting the following error when trying to generate lightmap UVs for the attached mesh:

Assertion failed: ChartB.Join[ Side ^ 1 ] == i [File:D:\dev\Unreal preview\Engine\Source\Developer\MeshUtilities\Private\LayoutUV.cpp] [Line: 374]

KERNELBASE.dll!UnknownFunction (0x00007ffdf6db5bf8) + 0 bytes [UnknownFile:0]
UE4Editor-Core.dll!FOutputDeviceWindowsError::Serialize() (0x00007ffdb7852b04) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\windows\windowsplatformoutputdevices.cpp:95]
UE4Editor-Core.dll!FOutputDevice::Logf__VA() (0x00007ffdb76e7568) + 159 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\misc\outputdevice.cpp:145]
UE4Editor-Core.dll!FDebug::AssertFailed() (0x00007ffdb76cc642) + 62 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\misc\outputdevice.cpp:220]
UE4Editor-MeshUtilities.dll!FLayoutUV::FindCharts() (0x00007ffdae4045d4) + 0 bytes [d:\dev\unreal preview\engine\source\developer\meshutilities\private\layoutuv.cpp:375]
UE4Editor-MeshUtilities.dll!FMeshUtilities::BuildStaticMesh() (0x00007ffdae3f32ba) + 0 bytes [d:\dev\unreal preview\engine\source\developer\meshutilities\private\meshutilities.cpp:2293]
UE4Editor-Engine.dll!FStaticMeshRenderData::Cache() (0x00007ffdb5574d13) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\engine\private\staticmesh.cpp:1138]
UE4Editor-Engine.dll!UStaticMesh::CacheDerivedData() (0x00007ffdb55751fc) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\engine\private\staticmesh.cpp:1634]
UE4Editor-Engine.dll!UStaticMesh::Build() (0x00007ffdb5570359) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\engine\private\staticmeshbuild.cpp:88]
UE4Editor-Engine.dll!UStaticMesh::PostEditChangeProperty() (0x00007ffdb559f4dc) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\engine\private\staticmesh.cpp:1417]
UE4Editor-CoreUObject.dll!UObject::PostEditChange() (0x00007ffdb86542d9) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\coreuobject\private\uobject\obj.cpp:215]
UE4Editor-StaticMeshEditor.dll!FLevelOfDetailSettingsLayout::ApplyChanges() (0x00007ffda6d5867e) + 0 bytes [d:\dev\unreal preview\engine\source\editor\staticmesheditor\private\staticmesheditortools.cpp:1956]
UE4Editor-StaticMeshEditor.dll!FMeshBuildSettingsLayout::OnApplyChanges() (0x00007ffda6d8dd93) + 60 bytes [d:\dev\unreal preview\engine\source\editor\staticmesheditor\private\staticmesheditortools.cpp:541]
UE4Editor-StaticMeshEditor.dll!TBaseSPMethodDelegateInstance_RetVal_NoParams::Execute() (0x00007ffda6d6d51f) + 17 bytes [d:\dev\unreal preview\engine\source\runtime\core\public\delegates\delegateinstancesimpl.inl:161]
UE4Editor-Slate.dll!TBaseDelegate_RetVal_NoParams::Execute() (0x00007ffdb4b460ba) + 6 bytes [d:\dev\unreal preview\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:1058]
UE4Editor-Slate.dll!SButton::OnMouseButtonUp() (0x00007ffdb4b72c05) + 17 bytes [d:\dev\unreal preview\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:188]
UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonUpEvent() (0x00007ffdb4a0c15c) + 23 bytes [d:\dev\unreal preview\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3489]
UE4Editor-Slate.dll!FSlateApplication::OnMouseUp() (0x00007ffdb49fb786) + 16 bytes [d:\dev\unreal preview\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:3456]
UE4Editor-Core.dll!FWindowsApplication::ProcessDeferredMessage() (0x00007ffdb77af7d9) + 12 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\windows\windowsapplication.cpp:1346]
UE4Editor-Core.dll!FWindowsApplication::DeferMessage() (0x00007ffdb77a1c4b) + 74 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\windows\windowsapplication.cpp:1637]
UE4Editor-Core.dll!FWindowsApplication::ProcessMessage() (0x00007ffdb77b0959) + 41 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\windows\windowsapplication.cpp:737]
UE4Editor-Core.dll!FWindowsApplication::AppWndProc() (0x00007ffdb779eee2) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\windows\windowsapplication.cpp:599]
USER32.dll!UnknownFunction (0x00007ffdf7ab2434) + 0 bytes [UnknownFile:0]
USER32.dll!UnknownFunction (0x00007ffdf7ab2297) + 0 bytes [UnknownFile:0]
UE4Editor-Core.dll!FWindowsPlatformMisc::PumpMessages() (0x00007ffdb784e816) + 48 bytes [d:\dev\unreal preview\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:757]
UE4Editor.exe!FEngineLoop::Tick() (0x00007ff71d698f22) + 8 bytes [d:\dev\unreal preview\engine\source\runtime\launch\private\launchengineloop.cpp:2111]
UE4Editor.exe!GuardedMain() (0x00007ff71d68eb0e) + 0 bytes [d:\dev\unreal preview\engine\source\runtime\launch\private\launch.cpp:133]
UE4Editor.exe!GuardedMainWrapper() (0x00007ff71d68eb7a) + 5 bytes [d:\dev\unreal preview\engine\source\runtime\launch\private\windows\launchwindows.cpp:125]
UE4Editor.exe!WinMain() (0x00007ff71d69a6f9) + 17 bytes [d:\dev\unreal preview\engine\source\runtime\launch\private\windows\launchwindows.cpp:201]
UE4Editor.exe!__tmainCRTStartup() (0x00007ff71d69b629) + 21 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]
KERNEL32.DLL!UnknownFunction (0x00007ffdf96e16ad) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x00007ffdf98934a5) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x00007ffdf98934a5) + 0 bytes [UnknownFile:0]

2

This mesh is freezing the editor when I try to generate the lightmap UVs

3

Hi Paul,

Thank you for reporting this. I’ve been able to reproduce the crash and submitted the bug report (TTP:348922).

However I was not able to get anything like you mentioned for the fence post. Everything checked out fine for me.

It should be noted though that this is a new feature that will be added to over the coming builds. I was able to take a look at your meshes in 3Ds Max and there is not a properly setup UV channel 1. You should have a UV here with your mesh broken apart. The Lightmap is being based off this UV channel and having the complex mesh is probably what caused the crash to happen. Things like Cylinders will need to be split down once side and flattened to get a properly LM.

Thank you!

Tim