Unreal engine mouse input problem (original) (raw)

November 1, 2024, 11:29am 1

We have a project on Unreal Engine 5 that works on linux and windows x86 machines with current build. However when we run this project on Jetson Linux on Jetson Agx Orin 64gb onclick event and finding mouse position with DPI scaling doesn’t work but without DPI scaling it captures mouse position however not the onclick event. We haven’t get an error on game project neither on system.
When we try to find hit location with linetracing Unreal Engine can’t detect location.
Is there a driver or a software that works on x86 Ubuntu but not in Jetson linux which can be cause of this problem?

linuxdev November 1, 2024, 9:03pm 2

You’ll need to find someone who knows the specific software to give you a good answer. I’ll add some information you might find to be of use.

If it is a hardware driver, then the driver for a desktop PC would simply be recompiled for this kernel. It is unlikely this is the problem if the mouse is any standard mouse. In that case it would use the USB HID drivers which are standard on every system. One way to determine more about this is to monitor “dmesg --follow”, and then plug in the mouse and see what log lines are added as a result of the mouse connector insert. This shows the USB steps, including binding of drivers to hardware.

In the case of using the Xorg X11 server, this too has its own drivers, but they are user space (the previous drivers are kernel space). This too would normally not be an issue. In a terminal of your system with issues run the command “echo $DISPLAY”. If it is “:0”, then the number “0” is what you are interested in; if it is some other “:<number>”, then that number is what you are interested in. After a normal boot, save a copy of the log file (I’m using “0” as the number, but if it is 1 or 10 or something else, substitute):
/var/log/Xorg.0.log

That log will contain some information regarding input devices (usually with an “event” name). This particular binding requires the udev system to recognize the device which was created as a result of the USB plug-in. This means that if the device is standard, then likely the device bound by the Xorg server will also always work. The most typical failure of this is when the Xorg server itself is modified and results in module load failure (the event devices use dynamically loadable modules; these fail if compiled against a different X server).

Between those two it should be possible to narrow down if the mouse drivers are an issue. However, it will still be useful to know if the Unreal Engine you are using has its own X server or how exactly that loads relative to the X server. For all I know it skips using X entirely (I don’t know anything about Unreal Engine 5). It is however likely it uses the same scheme on the desktop PC and the Jetson.

One thing which sometimes puts a kink in success is that the GPU of a Jetson is integrated (iGPU) directly to the memory controller. Desktop PCs have a discrete GPU (dGPU) which is attached through the PCI bus. Detection of the GPU thus differs depending on the environment. Most naive software out in the wild assumes the PCI detection works. I am guessing though that if the GPU were being missed, then there might be other issues. Still, it is a possibility until we know otherwise.

Posting that information can give some idea of whether or not the basics are in place. Keep in mind that as you gather this information, you can gather a copy of this on the working Linux desktop PC, and then compare them.

system Closed November 15, 2024, 9:04pm 3

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