Hi! This is a really interesting use case for sliders, and I can see what you're trying to achieve. The issue you're running into is related to how sliders work when they're applied sequentially to the same bones.
When you have two sliders both constraining the same bones, they apply their transformations one after another. This means the second slider is applying its animation on top of the result of the first slider, rather than both being applied independently to the setup pose. This is why you're seeing unexpected behavior when combining them - the X slider is trying to apply its translation/scale changes to bones that have already been transformed by the Y slider.
Here are a couple of approaches you could try:
Use Additive mode:
Try enabling the Additive checkbox on one or both of your sliders. When Additive is checked, the slider animation is applied relative to the existing pose, which might help with the compounding transformation issue. However, this may require adjusting your animations to work in an additive manner.
Restructure with parent/child bones:
Instead of having both sliders control the same bones directly, you could set up a parent-child bone hierarchy:
- Have the Y slider control a parent bone for vertical movement
- Have the X slider control a child bone for horizontal movement
- Weight your meshes to the child bone
This way, each slider operates on different bones in the hierarchy, and their effects combine more predictably.
Alternative: Use transform constraints with mapping bones:
Instead of sliders, you might consider using transform constraints with control bones. Create two control bones (one for X, one for Y movement), and use transform constraints to translate those movements into the desired head poses. This gives you more direct control over how the transformations combine.
The "reversal" and scale blowup you're seeing is likely because the second slider is interpreting the already-transformed pose as its starting point and applying changes from there, leading to compounding effects that quickly spiral out of control.
Would you be able to share your Spine project file? That would help in providing a more specific solution for your exact setup!
