3D long hair with head/shoulders torsion

Hi there,

I'm trying to reproduce this type of simulation with 3d mesh hair:

https://lens.snapchat.com/b91e037064334bb78f9aa807d231d2d7

By following this tutorial on the Snap AR channel, I managed to have pretty decent result, and I customized a bit the code to adjust the position of the mesh depending on a empty scene object. My only problem is, I don't manage to adjust the Z position correctly and the mesh seems to be in front of the face as we can see a gap between when I turn my head. Adjusting the Z value results in the overall size becoming smaller, but the gap remains. Is there something I could do about it, or a better technic to achieve this effect?

Thanks

bellow is the code I'm using:

// -----JS CODE-----

// @input SceneObject binding

// @input SceneObject root

// @input SceneObject head

// @input SceneObject nullObj







var bindingTransform = script.binding.getTransform();

var rootTransform = script.root.getTransform();

var rootOriginPosition = rootTransform.getWorldPosition();




var headTransform = script.head.getTransform();

var headOriginRotation = headTransform.getWorldRotation();

var shiftTransform = script.nullObj.getTransform();




function onUpdate()

{

var bindingPos = bindingTransform.getWorldPosition();

var shiftPos = shiftTransform.getWorldPosition();

var pos = bindingPos.add(shiftPos);

rootTransform.setWorldPosition(pos);

var bindingRot = bindingTransform.getWorldRotation();

var rot = bindingRot.multiply(headOriginRotation);




headTransform.setWorldRotation(rot);

}




var updateEvent = script.createEvent("UpdateEvent");

updateEvent.bind(onUpdate);