allow unfolding flat shapes

[alexneufeld]

closes #441

[shaise]

Thanks!
However, now if you select a side face, you do not get any error. Perhaps it is not that critical.

[alexneufeld]

Thanks! However, now if you select a side face, you do not get any error. Perhaps it is not that critical.

not critical, and totally unsolvable in the general case. All you need is one fillet to make a side face look unfoldable:

We could replace the root face selection step with a heuristic that selects a root based on something like 'largest-flat-planar-face'. That eliminates the possibility of unfolding 'in-place' though. Every other CAD software I've used works similarly to our current process (user selects a root face to unfold from) so I'm inclined to keep doing that.