The issue you're experiencing is related to how Spine processes constraints in order. When you use a transform constraint to attach bone "A" to the "Hip" bone, and then the physics constraints are applied to bone "A"'s children, the order matters significantly.
Understanding the problem:
Physics constraints are always influenced by their parent bone's movement. However, when you use a transform constraint to move bone "A", the physics on its child bones may not respond correctly because of the constraint order.
Here are some solutions to try:
1. Adjust the constraint order
The order in which constraints are applied is crucial. You can change this by dragging constraints in the tree view under the Constraints node. Try ensuring your transform constraint is applied before the physics constraints. This way, the physics can properly react to the movement caused by the transform constraint.
2. Use an intermediate bone setup
Create a helper bone structure:
- Keep your original bone "A" without the transform constraint
- Create a new bone "A-control"
- Apply the transform constraint to "A-control" (targeting the Hip)
- Parent bone "A" to "A-control"
- Keep the physics constraints on the children of bone "A"
This separation can help the physics constraints receive proper motion information.
3. Adjust the Mix value
If the physics seems completely unresponsive, check that the physics constraint's Mix value isn't set to 0. When Mix is set to 0, the physics constraint won't have any effect.
4. Check the Local and Relative settings
On your transform constraint, experiment with the Local and Relative checkboxes. These settings affect how the transform is applied and might help the physics respond more naturally to the movement.
The key is ensuring that the physics constraints can "see" the actual movement of their parent bones after all other constraints have been applied.
