Unreal Engine Issues and Bug Tracker (UE-151841)

Description

Engine crashes when building GPU lightmass in larger scenes. This does not occur on smaller maps like the Unreal Engine Templates. I was able to reproduce this issue in CitySamples SmallCity map.

This issue also occurs in 5.0.1

Steps to Reproduce

Open CitySample or any other large project with a considerable amount of textures
Turn GPU Lightmass plugin ON
Restart engine
Build GPU Lightmass

Actual Result: Engine crashes while building GPU Lightmass
Expected Result: Engine does not crash and builds as expected

Callstack

Assertion failed: Index <= 0xffff [File:D:\P4\5.1Main\Engine\Source\Runtime\Renderer\Private\VT\VirtualTextureAllocator.cpp] [Line: 114]

UnrealEditor_Renderer!FVirtualTextureAllocator::AcquireBlock() [VirtualTextureAllocator.cpp:114]
UnrealEditor_Renderer!FVirtualTextureAllocator::SubdivideBlock() [VirtualTextureAllocator.cpp:213]
UnrealEditor_Renderer!FVirtualTextureAllocator::MarkBlockAllocated() [VirtualTextureAllocator.cpp:324]
UnrealEditor_Renderer!FVirtualTextureAllocator::MarkBlockAllocated() [VirtualTextureAllocator.cpp:335]
UnrealEditor_Renderer!FVirtualTextureAllocator::MarkBlockAllocated() [VirtualTextureAllocator.cpp:335]
UnrealEditor_Renderer!FVirtualTextureAllocator::Alloc() [VirtualTextureAllocator.cpp:505]
UnrealEditor_Renderer!FVirtualTextureSystem::AcquireSpace() [VirtualTextureSystem.cpp:811]
UnrealEditor_Renderer!FAllocatedVirtualTexture::FAllocatedVirtualTexture() [AllocatedVirtualTexture.cpp:97]
UnrealEditor_Renderer!FVirtualTextureSystem::AllocateVirtualTexture() [VirtualTextureSystem.cpp:662]
UnrealEditor_GPULightmass!GPULightmass::FLightmapPreviewVirtualTexture::FLightmapPreviewVirtualTexture() [LightmapPreviewVirtualTexture.cpp:58]
UnrealEditor_GPULightmass!<lambda_981a586319f50e135455e5d11603dc34>::operator() [Scene.cpp:1067]
UnrealEditor_GPULightmass!TEnqueueUniqueRenderCommandType<`GPULightmass::FScene::AddGeometryInstanceFromComponent'::`2'::RenderThreadInitName,<lambda_981a586319f50e135455e5d11603dc34> >::DoTask() [RenderingThread.h:193]
UnrealEditor_GPULightmass!TGraphTask<TEnqueueUniqueRenderCommandType<`GPULightmass::FScene::AddGeometryInstanceFromComponent'::`2'::RenderThreadInitName,<lambda_981a586319f50e135455e5d11603dc34> > >::ExecuteTask() [TaskGraphInterfaces.h:1276]
UnrealEditor_Core!FNamedTaskThread::ProcessTasksNamedThread() [TaskGraph.cpp:761]
UnrealEditor_Core!FNamedTaskThread::ProcessTasksUntilQuit() [TaskGraph.cpp:650]
UnrealEditor_Core!FTaskGraphCompatibilityImplementation::ProcessThreadUntilRequestReturn() [TaskGraph.cpp:2128]
UnrealEditor_RenderCore!RenderingThreadMain() [RenderingThread.cpp:380]
UnrealEditor_RenderCore!FRenderingThread::Run() [RenderingThread.cpp:527]
UnrealEditor_Core!FRunnableThreadWin::Run() [WindowsRunnableThread.cpp:149]

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Unresolved

Component	UE - Graphics Features
Affects Versions	5.0.1, 5.1
Target Fix	5.5

Created	May 12, 2022
Resolved	Apr 6, 2023
Updated	Jan 10, 2024

UE-151841

Engine crashes when building GPU Lightmass in large scenes

Engine crashes when building GPU Lightmass in large scenes

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