[cad-linux] Viewport

I'm writing a tiny modular CAD.  Since I'm not particularly fond of
GUI programming and I'd like to concentrate on the engine, I'm looking
for a simple viewport program that reads bi- or tri- dimensional data
from the standard input and displays it.  Handling of image aspect
must absolutely make sense for a CAD program (i.e. no squares 10 units
wide and 2 units high ;-) as is common in dataplotting).  `Naming' of
drawing entities and selective update would be a plus, but not
strictly necessary.

I tried `graph' from the GNU plotutils and I stumbled on the 10x2
square problem.  I whipped a little interface with Ruby and Tk and,
well, my above mentioned fondness for GUIs showed all its
consequences. :-) Do you know of anything that resembles this
description?  (Of course, if you happen to know your way among
widgets, have a spare hour, and some curiosity for an experimental
project, you're very welcome, too. :-))

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