Displaying the length this way would work only if you draw a closed convex room.
What about internal walls that will be used to separate rooms in a home?
What about concave rooms?
What about convex rooms with angles different than 90°?
There's no way to anticipate these cases and what the user will draw!
An other idea I had in mind for a while was to keep the length as it's displayed, and add an other label + value that would display the length minus the wall thickness. But I can't imagine a (short) label that new users will understand without troubling them, and anyway subtracting thickness from length isn't so hard, is it?
The only simple workaround I found until now was to let users create the walls around a room by double-clicking in it...
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Emmanuel Puybaret, Sweet Home 3D creator
