It's often very helpful to be able to "invert" the rotation of a local constraint. I previously did this by inverting the scale of the parent object when calculating local rotations.
VRC Parent and Rotation Constraints do not seem to behave as expected under a parent with inverted scale.
Expected Behavior: Rotation Values are copied as is from the Source to the Target.
Actual Behavior: Rotation Constraints ignore the parent scale.
(I have attached a screenshot, but I will also do my best to explain via text)
Hierarchy:
  • Source Object
  • Root Object (X Scale is -1)
- Target Object (Rotation Constrained to Source Object with Local Space Checked)
I then rotate the source object 30 degrees in Y. The target object automatically moves -30 degrees in Y relative to it's parent.
This also occurs for the Rotation portion of Parent Constraints.
For local rotations, what I am looking for is a weighted copy paste of the raw transform values pasted into the Target Object.
I've marked this as a Bug Report, because I do not know your design approach to this situation. If you have a different design approach, please convert to Feature Request and respond and to let us know. However, be aware that this situation is one limitation of the currently implemented solution.
Thank you so much for looking into this!