This adds a camera rig useful for 2D productions. It is copied from this repository, of which I’m the original co-author. It follows the refactor from D6543.

Its principle is explained in some detail in this article, but here it is again briefly:
In a 2D production (and some shots in 3D as well), you sometimes need to rotate the camera while zooming, effectively "cropping" the field, just as you would using a rostrum camera. This is tedious and error-prone if animating basic transforms, so this rig implements a more intuitive way to do that, by just animating the two lower corners of the camera’s field.

This involved a bit of further refactoring, to separate generation and UI into aspects common to all rigs, common to 3D rigs, and specific to each rig.

I also improved other stuff I noticed in the add-on (well, you know that’s just, like, my opinion, man…):

• add the GPL license block to create_widgets.py, which I’d forgotten;
• rename arm[ature] to rig in some functions, for consistency and to avoid confusion with the crane’s arm;
• changes to the UI panel:
  • remove the boxes, which I didn’t feel made the UI any clearer,
  • put focal length at the top of the panel,
  • group related properties using aligned columns,
  • change the Make Camera Active operator’s poll method, so that it is always visible in the UI, but greyed out when the camera is already active.

Before:

After:

@Brendon Murphy (meta-androcto) I’m adding you as a reviewer since this adds a new feature and I’d like your opinion on that.
If this is accepted, I will support and maintain the 2D rig.