The modifier was originally written with the assumption that exactly one
modifier controlled exactly one page. Of course, artists began using
multiple Note Popup modifiers to show the same GUI page in multiple
places. So, be sure that we only export the GUI objects once.
Our calculations try to fill the entire screen with the GUI objects. So,
really, what we want the GUI Camera scaling to do is allow the artist to
make the GUI smaller onscreen by pushing the camera away. This is a
*less than* 100% scaling.
We will now calculate the area-weighted normal of all polygons in the
GUI page, then flip it to create the direction that the GUI camera
should face. This will, theoretically, be more intuitive to artists in
that the GUI camera should always point at what they've modelled instead
of imposing arbitrary rules on the coordinate system of GUI objects.
This adds just enough plumbing to be able to export GUI popup notes
using the standard xDialogToggle.py. There are still a number of TODOs
and FIXMEs in the basic stuff, but the design is mostly solid. The idea
is that you'll create a GUI page for any objects that need to appear in
a GUI. The GUI does not require an explicit GUI camera, however. For
now, an automatic GUI camera will be made facing the largest object's -Z
axis.