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I have a custom VR device I'm testing and I'm looking to do something which should be simple with my desktop monitor settings. Essentially I want to go from a regular desktop, this:

enter image description here

To having this screen repeated side-by-side split down the middle, like this:

enter image description here

And it's literally just a real-time copy of the desktop.

For reference, I am using a 800 x 480 display, in case that's relevant.

Ideally I would like to put my computer permanently into this display mode, so that every time it boots up it's like this automatically.

Thanks in advance for any help!

EDIT - I want to confirm that I'm trying to do this simple task on a Raspberry Pi, which should be a type of debian Linux if I understand correctly.

JDS
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  • 800 x 480 is too large so you want it as twice 400 x 480? – harrymc Apr 22 '20 at 20:17
  • Yeah I'm actually OK with either solution: cut off the original in half and duplicate it, or "squish" the original in half and duplicate it. I suppose I'd prefer the former (which is what the second image shows). – JDS Apr 22 '20 at 20:24
  • This may go a bit beyond the scope of your question, but wouldn't you also need to render the desktop on a plane at some distance in 3D for this to even look readable in VR? You might find that copying the 2D surface to each eye is really uncomfortable unless this "custom VR device" has optics built specifically for this (which means it isn't really a VR device at all). You usually have to correct for the distortion of any lenses too! – Romen Apr 28 '20 at 13:36
  • @Romen thanks for the concern but for my approach I only need the two screens side-by-side, I have other methods to rectify the display to the user. This is my main hurdle lol. – JDS Apr 28 '20 at 23:10

1 Answers1

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I see two parts here:

  1. Split the screen into two virtual displays
  2. Mirror the left display on the right.

Splitting the screen

Splitting the screen is addressed in the post
How to vertically split widescreen into two virtual workspaces on Ubuntu/Gnome?.

This uses the free and open-source Fake Xinerama. Using it is described in detail in this answer. If this does not work for you, then another answer uses xrandr to split the screen.

An alternate method that uses Compiz is described in the Ask Ubuntu post Split monitor in two.

Mirroring the display

See the post Mirror display on Ubuntu 18.04 for an answer that uses xrandr to mirror the displays:

xrandr --output eDP-1 --output DP-2 --same-as eDP-1

Running xrandr without arguments gives the list of displays and their resolutions, to be used as above.

harrymc
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  • Thanks for the answer! I would appreciate if you could put together a list of simple commands/instructions for the first part, and then I could quickly test and accept your answer. Cheers – JDS Apr 25 '20 at 20:38
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    The references I gave have explicit instructions and commands. Some adaptation will be required on your side, for example perhaps for the names of the displays and the required resolutions. As I do not have your environment, I cannot guess at these details. – harrymc Apr 26 '20 at 08:46
  • Apologies should have specified - I am using Raspbian (raspberry pi OS). I am a newby and assumed the linux versions would be similar enough for something like this. – JDS Apr 26 '20 at 18:28
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    The utilities in the answer are pretty standard across all distributions, so should work on Raspbian the same as on any other Linux version. Look on it as an occasion for learning something more about Linux. – harrymc Apr 26 '20 at 19:28