Update: Tobii Technology picked up the plugin and refined it to super good quality, so I recommend using this repo over this one for anyone who is interested: https://github.com/TobiiTechnology/EyeXforUE4/ /Temaran Initial info: Currently, for this plugin to work, you need to do some changes to the core source, this will not change until I can get Epic to pull these changes :) For more info on the changes see: https://forums.unrealengine.com/showthread.php?7812-Transforming-O-S-mouse-coordinates-to-viewport-pixels In a nutshell, you need to do these changes: To UnrealClient.h in the FViewport class add: virtual bool OperatingSystemPixelToViewportPixel(FIntPoint const * const OperatingSystemPoint, FIntPoint& ViewportPoint) const { return false; } virtual bool ViewportPixelToOperatingSystemPixel(FIntPoint const * const ViewportPoint, FIntPoint& OperatingSystemPoint) const { return false; } override them in FSceneViewport.h and then create these implementations in SceneViewport.cpp: bool FSceneViewport::OperatingSystemPixelToViewportPixel(FIntPoint const * const OperatingSystemPoint, FIntPoint& ViewportPoint) const { auto TransformedPoint = CachedGeometry.AbsoluteToLocal(FVector2D(OperatingSystemPoint->X, OperatingSystemPoint->Y)); ViewportPoint.X = TransformedPoint .X; ViewportPoint.Y = TransformedPoint .Y; return true; } bool FSceneViewport::ViewportPixelToOperatingSystemPixel(FIntPoint const * const ViewportPoint, FIntPoint& OperatingSystemPoint) const { auto TransformedPoint = CachedGeometry.LocalToAbsolute(FVector2D(ViewportPoint->X, ViewportPoint->Y)); OperatingSystemPoint.X = TransformedPoint .X; OperatingSystemPoint.Y = TransformedPoint .Y; return true; } Then, to use this plugin: 1. First create a new folder under your unreal project folder called "Plugins" 2. Create an appropriate subfolder. I chose "EyeXEyetracking" 3. Clone / copy this repo to that subfolder 4. Download the EyeX SDK and put the libs/includes in the ThirdParty/EyeX/ folder. More directions for that in that folder 5. Put the relevant client dll into the Binaries/PLATFORM/ subfolder. if x64, use the x64 version of Tobii.EyeX.Client.dll and conversely for x86. You can find the dll in the ThirdParty/EyeX/lib/PLATFORM/ folders 6. Regenerate your solution using the UE4 shell extension 7. Build the project 8. Start the editor and open the plugin viewer (can be found under the windows->Plugins menu) 9. Add a reference to the module in your build script, the relevant row might look something like (Your buildfile is probably called something like MYPROJECT.Build.cs: PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "EyeXEyetracking" }); 10. Program against the API using the provided singleton FEyeXEyetracking::GetHost().METHODYOUWANTTOCALL(); 11. HAVE FUN!!! /Temaran