MaterialQualityLevel 0 (or 2) stalls 4.22

Development Rendering
, , , , ,
6

Since the both the

check(OutUniformExpressionCache.UniformBuffer->GetLayout() == UniformBufferStruct.GetLayout());
RHIUpdateUniformBuffer(OutUniformExpressionCache.UniformBuffer, TempBuffer);

functions cause the engine to crash I’m assuming the (IsValidRef(OutUniformExpressionCache.UniformBuffer)) If check is returning TRUE when it should be returning FALSE. But forcing it down the FALSE (else) statement so that only

OutUniformExpressionCache.UniformBuffer = RHICreateUniformBuffer(TempBuffer, UniformBufferStruct.GetLayout(), UniformBuffer_MultiFrame);

is called, the crash does not occur. My edited version of the function is below:

void FMaterialRenderProxy::EvaluateUniformExpressions(FUniformExpressionCache& OutUniformExpressionCache, const FMaterialRenderContext& Context, FRHICommandList* CommandListIfLocalMode) const
{
	check(IsInParallelRenderingThread());

	SCOPE_CYCLE_COUNTER(STAT_CacheUniformExpressions);
	
	// Retrieve the material's uniform expression set.
	const FUniformExpressionSet& UniformExpressionSet = Context.Material.GetRenderingThreadShaderMap()->GetUniformExpressionSet();

	OutUniformExpressionCache.CachedUniformExpressionShaderMap = Context.Material.GetRenderingThreadShaderMap();

	const FShaderParametersMetadata& UniformBufferStruct = UniformExpressionSet.GetUniformBufferStruct();
	FMemMark Mark(FMemStack::Get());
	void* TempBuffer = FMemStack::Get().PushBytes(UniformBufferStruct.GetSize(), SHADER_PARAMETER_STRUCT_ALIGNMENT);

	UniformExpressionSet.FillUniformBuffer(Context, TempBuffer);

	if (CommandListIfLocalMode)
	{
		OutUniformExpressionCache.LocalUniformBuffer = CommandListIfLocalMode->BuildLocalUniformBuffer(TempBuffer, UniformBufferStruct.GetSize(), UniformBufferStruct.GetLayout());
		check(OutUniformExpressionCache.LocalUniformBuffer.IsValid());
	}
	else
	{
		OutUniformExpressionCache.UniformBuffer = RHICreateUniformBuffer(TempBuffer, UniformBufferStruct.GetLayout(), UniformBuffer_MultiFrame);
	}

	OutUniformExpressionCache.ParameterCollections = UniformExpressionSet.ParameterCollections;

	OutUniformExpressionCache.bUpToDate = true;	
	
}

With this edit a recompile of the editor / engine the crash does not occur.