inspired by https://github.com/ekymo/homeRoughEditor
- The editor's world coordinate unit is millimeters (mm).
- The Unit selector (meters/feet/pixels) only changes how lengths/areas are displayed.
- meters:
$1,m = 1000,mm$ - feet:
$1,ft = 304.8,mm$ - areas are converted from
$mm^2$ to$m^2$ /$ft^2$ accordingly.
- meters: