Based on your description, it sounds like you're experiencing issues with the eye control bone not following the face properly when using transform constraints. Here are some approaches to help solve this problem:
Understanding the Core Issue
When you constrain the Eye Control Bone to the Frontal Facial Bone, the constraint applies transformations that may not perfectly match the distortion happening in your weighted face mesh. This causes the eyes to appear to move out of their sockets.
Solution 1: Using Weights Instead of Constraints
Instead of using a transform constraint on the Eye Control Bone, consider binding it to the face bones using weights:
- Bind the Eye Control Bone (and related eye bones) to both the Frontal Face Bone and Posterior Face Bone in setup mode
- Use weight painting to control how much each bone influences the eye position
- This way, the eyes will follow the mesh deformation naturally
For the eyelids, you can maintain their current setup since they need independent control. The key is that the Eye Control Bone itself follows the face through weights, while the eyelid bones remain children of the Eye Control Bone for independent animation.
Solution 2: Adjusting Transform Constraint Settings
If you prefer using constraints, try these adjustments:
- Experiment with different mix values for translation and rotation separately in the transform constraint
- The translation mix might need to be lower (like 20-60%) to create a subtle "drag" effect that adds depth
- Consider setting up the constraint with different values for different directions of movement
You might find that a translate mix around 60-80% works better than 100%, allowing some independence while still keeping the eyes roughly in place.
Solution 3: Additional Control Bones
Create an intermediate bone hierarchy:
- Eye Socket Bone (weighted to face bones)
- Eye Control Bone (child of socket bone)
- Eyelid bones and eye bones
This way, the Eye Socket Bone follows the face deformation through weights, and you maintain full control over eye direction through the Eye Control Bone.
Important Consideration About Binding
Make sure all eye-related bones were bound to the face bones in the same pose (preferably setup mode). If bones are bound at different times when the face is in different positions, this can cause alignment issues. If this is the case, you can use Update bindings (https://esotericsoftware.com/spine-weights#Update-bindings) to rebind all bones in a consistent state.
The weight-based approach is generally more reliable for this type of setup, as it allows the eyes to follow the organic deformation of the face mesh naturally, rather than trying to approximate it with constraint values.
