I am trying to rig a tree using Vellum and have run into an issue that I can't quite solve. With a Wire Solver rig, I can attach each hierarchy of the tree to a corresponding Wire Object and the constraints track with the sim geo as expected. This meaning that as the trunk moved in the wind, all branches were glued at their base to the trunk.

With Vellum, I thought I could utilize the Attach To Geometry constraint's ability to attach using a target_prim, target_uv, and target_path, but I quickly realized that the attach constraint is only updated at the beginning of the solve. So when the trunk moves, the Attach To Geometry constraints are actually constrained to the positions of the trunk BEFORE the vellum solver does it's thing.




I have gotten sort of close using the flow attached, where the target_path is pointing to the base geo on the first frame, then switches to the dop geo to track, but as seen in the screenshot all constraints are 1 frame behind.




Is there a better way to attach branches using a hierarchy? I like the attach to geometry because it allows tracking without the need for extra sample points but would be happy to find any solution.

Cheers!