Unreal Engine Issues and Bug Tracker (UE-56266)

Description

There is an issue occurring where Unreal crashes when you connect a scalar node to scalar input when the material function has a vertex interpolator. This issue causes the engine to crash, but the issue does not occur if the scaler does not have a parameter

This issue appears to be a regression.
Versions Tested
4.18.3 CL - 3832480 - Issue does not occur
4.19.0 CL - 3944462 - Issue occurs
4.20.0 CL - 3879785 - Issue occurs

Steps to Reproduce

Open Project provided
Create a new material and open it > Or open the material provided
Add the material function provided into the Material Editor
Add a scaler parameter to the Material Editor graph
Connect the Scaler Parameter as an input into the material function
Result: The Editor crashes
Expected Result: The Editor does not crash

Callstack

Assertion failed: ParameterOwnerStack.Num() [File:D:\Build\++UE4+Release-4.19+Compile\Sync\Engine\Source\Runtime\Engine\Private\Materials/HLSLMaterialTranslator.h] [Line: 1912]

UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:419]
UE4Editor_Engine!FHLSLMaterialTranslator::ScalarParameter() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:2248]
UE4Editor_Engine!UMaterialExpressionScalarParameter::Compile() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialexpressions.cpp:6134]
UE4Editor_Engine!FHLSLMaterialTranslator::CallExpression() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:2004]
UE4Editor_Engine!FExpressionInput::Compile() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialshared.cpp:106]
UE4Editor_Engine!UMaterialExpressionFunctionInput::Compile() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialexpressions.cpp:11318]
UE4Editor_Engine!FHLSLMaterialTranslator::CallExpression() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:2004]
UE4Editor_Engine!FExpressionInput::Compile() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialshared.cpp:106]
UE4Editor_Engine!UMaterialExpressionMultiply::Compile() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialexpressions.cpp:2446]
UE4Editor_Engine!FHLSLMaterialTranslator::CallExpression() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:2004]
UE4Editor_Engine!FExpressionInput::Compile() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialshared.cpp:106]
UE4Editor_Engine!UMaterialExpressionVertexInterpolator::CompileInput() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialexpressions.cpp:14073]
UE4Editor_Engine!FHLSLMaterialTranslator::GatherCustomVertexInterpolators() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:339]
UE4Editor_Engine!FHLSLMaterialTranslator::GatherCustomVertexInterpolators() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:360]
UE4Editor_Engine!FHLSLMaterialTranslator::Translate() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\hlslmaterialtranslator.h:511]
UE4Editor_Engine!FMaterial::BeginCompileShaderMap() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialshared.cpp:1819]
UE4Editor_Engine!FMaterial::CacheShaders() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialshared.cpp:1752]
UE4Editor_Engine!FMaterial::CacheShaders() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\materialshared.cpp:1634]
UE4Editor_Engine!UMaterial::CacheShadersForResources() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\material.cpp:2943]
UE4Editor_Engine!UMaterial::CacheResourceShadersForRendering() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\material.cpp:2861]
UE4Editor_Engine!UMaterial::PostEditChangeProperty() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\engine\private\materials\material.cpp:3945]
UE4Editor_CoreUObject!UObject::PostEditChange() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:333]
UE4Editor_MaterialEditor!FMaterialEditor::UpdatePreviewMaterial() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\materialeditor\private\materialeditor.cpp:1607]
UE4Editor_MaterialEditor!FMaterialEditor::UpdateMaterialAfterGraphChange() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\materialeditor\private\materialeditor.cpp:3892]
UE4Editor_MaterialEditor!FMaterialEditorUtilities::UpdateMaterialAfterGraphChange() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\materialeditor\private\materialeditorutilities.cpp:112]
UE4Editor_UnrealEd!UMaterialGraphSchema::TryCreateConnection() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\unrealed\private\materialgraphschema.cpp:559]
UE4Editor_GraphEditor!FDragConnection::DroppedOnPin() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\grapheditor\private\dragconnection.cpp:212]
UE4Editor_GraphEditor!SGraphPin::OnDrop() [d:\build\++ue4+release-4.19+compile\sync\engine\source\editor\grapheditor\private\sgraphpin.cpp:759]
UE4Editor_Slate!<lambda_74ecb22bb70e3f50c9d83154dfa5c688>::operator()() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5477]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FPointerEvent,<lambda_74ecb22bb70e3f50c9d83154dfa5c688> >() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:266]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5473]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5927]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5907]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1726]
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2172]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:889]
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:726]
user32
user32
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:129]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3263]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\build\++ue4+release-4.19+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253]
kernel32
ntdll

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Fixed

Component	UE - Graphics Features
Affects Versions	4.19, 4.20
Target Fix	4.20

Fix Commit	3965567
Main Commit	4091081
Release Commit	4095966

Created	Mar 19, 2018
Resolved	Mar 26, 2018
Updated	May 31, 2018

View Jira Issue

UE-56266

Unreal crashes when you connect scalar node to scalar input, when material function has a vertex interpolator

Unreal crashes when you connect scalar node to scalar input, when material function has a vertex interpolator

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