Blender Git Loki

Bugfix #8736: Follow Path constraints does not work for Bones

This appears to be a long-standing bug, and it only affected the Follow-Path constraint as it was the only one which was dependant on time-based changes. An oversight in the depsgraph code meant that Follow-Path constraints on armature bones were not evaluated, unless there was an Action or some NLA-Strips for that armature.

I've added a new flag to pose->flag (POSE_CONSTRAINTS_TIMEDEPEND) which only gets set/cleared by update_pose_constraint_flags. This flag indicates that the depsgraph needs to do an update for such cases, and will require going in/out of EditMode to set this for old files.
It's been implemented as such to avoid having costly searches when trying to run animations realtime (as is done for modifiers).