Previously only the active object was used.
Use coroutines to support baking frames for multiple objects at once,
without having to playback the animation multiple times.
We need to leave tweak mode before trying to modifiy the action as doing
so will leave Blender in a semi-corrupted state.
Reviewers: #animation
Reviewed by: aligorith
Maniphest Tasks: T48397
Differential Revision: https://developer.blender.org/D2119
Caused by own rBfb7ff31315a1c9 - not surprising code using Object.matrix_local
in other contexts than mere Object parenting fails, since it was using a broken
implementation before...
Note that whole NLA_OT_Bake op would need some love, it is quite brittle in many aspects.
there are cases where you want to use visual-keying but not remove constraints, also it wasnt obvious that clearing constraints used a different method of keyframing.
So split these into 2 options.
bake_action tries to make kind of a 'visual keying'... On one side, this is rather stupid when you keep constraints (in this case, keying actual loc/rot/scale transforms, i.e. matrix_basis, is enough, doing more would lead to unexpected behavior with some constraints). On the other one, making a good visual keying of bones is *really* tricky, so now using the new object's convert_space() func to compute that (when the user chooses to remove the constraints).
Incidentally, this greatly simplifies the code of bake_action!
