Skinned Mesh Renderer -> Root Bone

I have searched the entire internet for an answer and found none, so i decide to create a way of not doing this manually.

First, i created a class to generate a button for my function on the inspector:

 using UnityEngine;
 using UnityEditor;
 
 [CustomEditor(typeof(BoundRecalculate))]
 public class BoundRecalculatorMenu : Editor
 {
     public override void OnInspectorGUI()
     {
         DrawDefaultInspector();
 
         BoundRecalculate script = (BoundRecalculate)target;
 
         if(GUILayout.Button("Recalculate Bounds")) {
             script.calculate();
         }
     }
 }
 

then, i created a function to recalculate the bounds of my meshes:

 using UnityEngine;
 
 public class BoundRecalculate : MonoBehaviour
 {
     [SerializeField]
     GameObject target;
 
     public void calculate() {
         foreach( Transform child in target.transform ) {
             if(child.GetComponent<SkinnedMeshRenderer>() != null) {
                 SkinnedMeshRenderer skinnedMeshRenderer = child.GetComponent<SkinnedMeshRenderer>();
                     skinnedMeshRenderer.rootBone = skinnedMeshRenderer.bones[skinnedMeshRenderer.sharedMesh.boneWeights[0].boneIndex0];
                     skinnedMeshRenderer.updateWhenOffscreen = true;
                     Bounds bounds = new Bounds();
                     Vector3 center = skinnedMeshRenderer.localBounds.center;
                     Vector3 extents = skinnedMeshRenderer.localBounds.extents;
                     bounds.center = center;
                     bounds.extents = extents;
                     skinnedMeshRenderer.updateWhenOffscreen = false;
                     skinnedMeshRenderer.localBounds = bounds;
             }
         }
     }
 }

what this does it to get the target object and find every single child that has a Skinned Mesh Renderer on it, then it get the bone the first bone of the first vertice ( not the most used bone, but the first, this may be a problem to some cases, but worked fine for my case ), and set it as root bone (this is needed so the bound will follow the character movement), last but not least, it sets the updatewhenoffscreen to on, so we can get the correct bound to that mesh, and then turn it off, setting the saved values to our finished bound.

I hope this come to be usefull to others, sorry for my bad english.