I have a little question regarding display configuration. I'm planning to buy my first VR headset this year, and apart from gaming I also plan to use it for normal desktop activity as a potential replacement for my monitor. Unfortunately not all VR devices offer the option to switch between drawing the screen on both eyes and stretching it across both eyes: Some will always cause the left half of the screen to appear on the left eye and the right half on the right eye, making it unusable for standard activity.

I'd need the display manager to do one simple thing if I encounter this scenario: Crush and duplicate the image horizontally, ideally just on the VR device and not my normal monitor. For example: I'm currently using a 1920 x 1080 monitor. With this mode turned on, X11 would keep the hardware resolution unchanged, but scale the screen to 960 x 1080 / 960 x 540 then fit it in twice.

Is there such a feature in X11 / Wayland or the KDE display manager? What's the easiest way to match the side-by-side stereoscopic format system wide? Thank you.

I almost managed to get this running. There's an easy way to translate a display however you want using xrandr. I even found the exact vectors needed for a 1080p screen:

Left eye: xrandr --output DVI-D-0 --transform 2,0,0,0,1,-0,0,0,1
Right eye: xrandr --output DVI-D-0 --transform 2,0,-1920,0,1,-0,0,0,1

The problem is that I can't take an output and re-input it into the same device twice. I'd need to tell X to create two virtual displays, then merge those into the actual device with individual transforms. This is overly complicated though... there must be a better way.