Hey Mike, hey all,
For those who want to know what it means, this page explains it well:
InputCoordinateTransformation - Ubuntu wiki
Invert rotate (clockwise or counterclockwise 180°)
$ xrandr -o inverted
Not all graphics drivers support rotation
with a transformation matrix of:
⎡ -1 0 1 ⎤ ⎜ 0 -1 1 ⎥ ⎣ 0 0 1 ⎦
It covers how the matrix is to be understood and how you set it on the command line at runtime of X server. The option line above in Mike’s posting is for permanent setting in xorg.conf (and its subparts in xorg.conf.d directory), whose man page says:
Option “TransformationMatrix” “a b c d e f g h i”
- Specifies the 3x3 transformation matrix for absolute input devices. The input device will be bound to the area given in the matrix. In most configurations, “a” and “e” specify the width and height of the area the device is bound to, and “c” and “f” specify the x and y offset of the area. The value range is 0 to 1, where 1 represents the width or height of all root windows together, 0.5 represents half the area, etc. The values represent a 3x3 matrix, with the first, second and third group of three values representing the first, second and third row of the matrix, respectively. The identity matrix is “1 0 0 0 1 0 0 0 1”.
– Source: xorg.conf(5)