GTX-RTEMU-bin-patch 5.4.3

Click the Green button above scroll to bottom select "Download Zip" to get a zipped format and restore to C:\Program Files\Epic Games\UE_5.4

C:\Program Files\Epic Games\UE_5.4\Engine\Binaries\Win64\UnrealEditor-D3D12RHI.dll overwrite

The patched control file is in this package

C:\Program Files\Epic Games\UE_5.4\Engine\Config\ConsoleVariables.ini overwrite

Make sure you have changed the contol files as described in the Epic Forum Thread correctly

Solved : Cant Enable RayTracing in UE5 (gtx 1060)(Nvidia Pascal)

at Epic Forum page

LEGAL STUFF If you use this patch there is NO WARRANTY NO SUPPORT and NO LIABILITY BY EPIC AND ANY OTHER PARTIES Your installation of 5.4 binary will not be production

The first change was to add the ability to use the variable DXR_ALLOW_EMULATED_RAYTRACING in the WindowsD3D12Device.cpp file. I’m not making games and just using the path tracer to make images, so i set this to be on by default so i wouldn’t have to edit anything in the ConsoleVariables.ini file. After compiling it (thankfully it took only a few seconds to compile) Unreal ran, but i wasn’t getting any ray tracing. Checking the Output Log, and searching for ‘D3d12’ i saw :

Ray tracing is disabled because D3D12 ray tracing tier 1.1 is required but only tier 1.0 is supported Which seems to have moved the tier 1.0 cards to the ‘do not enable’ side of the logic. Undoing this change got me up and running with ray tracing.

This worked for me and my 1080. Hope it will help others.

Here are the files with their changes: …\UnrealEngine\Engine\Source\Runtime\D3D12RHI\Private\Windows\WindowsD3D12Device.cpp

change

#define DXR_ALLOW_EMULATED_RAYTRACING 0

#if DXR_ALLOW_EMULATED_RAYTRACING
int32 GAllowEmulatedRayTracing = 0;
to

#define DXR_ALLOW_EMULATED_RAYTRACING 1

#if DXR_ALLOW_EMULATED_RAYTRACING
int32 GAllowEmulatedRayTracing = 1;

and

…\UnrealEngine\Engine\Source\Runtime\D3D12RHI\Private\D3D12Adapter.cpp

change

UE_LOG(LogD3D12RHI, Log, TEXT("Ray tracing is disabled because D3D12 ray tracing tier 1.1 is required but only tier 1.0 is supported."));

to

UE_LOG(LogD3D12RHI, Log, TEXT("Ray tracing emulation is now enabled. Use at own risk. D3D12 tier 1.1 check ignored. Tra-La-La!"));
GRHISupportsRayTracing = RHISupportsRayTracing(GMaxRHIShaderPlatform);
GRHISupportsRayTracingShaders = GRHISupportsRayTracing && RHISupportsRayTracingShaders(GMaxRHIShaderPlatform);

For version 5.5.1 the followng patch is needed as there will be a UE5 crash

Thanks. I’ve tested it and it doesn’t work for me at all. UE crashes with error saying:

Assertion failed: GRHIGlobals.RayTracing.SupportsDispatchIndirect [File:C:\Users\Owner\source\repos\ue5Lgpu551\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp] [Line: 4977] 
RHIRayTraceDispatchIndirect may not be used because DXR 1.1 is not supported on this machine.

The fix to this is comment out the failing line to stop checking of Tier 1.1

…\UnrealEngine\Engine\Source\Runtime\D3D12RHI\Private\D3D12RayTracing.cpp at about line 4977

	//@GTXEMU Remove teir 1.1 crash
	//checkf(GRHISupportsRayTracingDispatchIndirect, TEXT("RHIRayTraceDispatchIndirect may not be used because DXR 1.1 is not supported on this machine."));