I'm trying to export a bone animation. I've followed a lot of the suggestions found in this helpful tutorial, with success. Near the top, they suggest that I avoid unchecking the 'Inherit Rotation' box on any bones, as it will not export properly. They also suggest the following vague workaround:
There's a tricky workaround for this, which is creating a helper bone which the bone that you don't want to rotate will copy its rotation.
Can someone explain this workaround in more detail for me? If you're familiar with the armature created by the Rigify add-on, I'd like the bone called 'spine' to not rotate with the bone called 'hips', but I would still like 'spine' to follow 'hip's position. How can I achieve this without unchecking Inherit Rotation?
Update: I've included the .blend file here. The bone that has 'inherit rotation' unchecked is the 'spine' bone. I'd like to be able to use the workaround on that bone. When I load this model into Assimp, his whole upper body rocks right and left (as if the spine bone was inheriting the rotation of the hips bone).