代码如下可直接调用

  MeshTool.SpawnCollider(mode);

using UnityEngine;

public class MeshTool
{

    public static Bounds SpawnCollider(Transform target)
    {
        Vector3 pMax = Vector3.zero;
        Vector3 pMin = Vector3.zero;
        Vector3 center = Vector3.zero;

        Vector3 oldPos = target.transform.position;
        Quaternion oldQua = target.transform.rotation;
        Vector3 oldScale = target.transform.localScale;

        target.transform.position = Vector3.zero;
        target.transform.rotation = Quaternion.identity;
        target.transform.localScale = Vector3.one;

        Bounds bounds = CalcBounds(target, ref pMax, ref pMin, ref center);

        BoxCollider collider = target.GetComponent<BoxCollider>();
        if (collider == null)
        {
            collider = target.gameObject.AddComponent<BoxCollider>();
        }
        collider.center = bounds.center;
        collider.size = bounds.size;

        target.transform.position = oldPos;
        target.transform.rotation = oldQua;
        target.transform.localScale = oldScale;

        return bounds;
    }

    private static Bounds CalcBounds(Transform obj, ref Vector3 pMax, ref Vector3 pMin, ref Vector3 center)
    {
        Renderer meshRenderer = obj.GetComponent<Renderer>();

        if (meshRenderer != null)
        {
            Bounds b = meshRenderer.bounds;
            pMax = b.max;
            pMin = b.min;
            center = b.center;
        }

        RecursivelyCalcBounds(obj.transform, ref pMax, ref pMin);

        CalculateCenter(pMax, pMin, out center, ref pMax, ref pMin);

        Vector3 size = new Vector3(pMax.x - pMin.x, pMax.y - pMin.y, pMax.z - pMin.z);
        Bounds bound = new Bounds(center, size);

        return bound;
    }

    private static void CalculateCenter(Vector3 max, Vector3 min, out Vector3 center, ref Vector3 pMax, ref Vector3 pMin)
    {
        float xc = (pMax.x + pMin.x) / 2f;
        float yc = (pMax.y + pMin.y) / 2f;
        float zc = (pMax.z + pMin.z) / 2f;

        center = new Vector3(xc, yc, zc);
    }

    private static void RecursivelyCalcBounds(Transform obj, ref Vector3 pMax, ref Vector3 pMin)
    {
        if (obj.transform.childCount <= 0)
        {
            return;
        }

        foreach (Transform item in obj)
        {
            Renderer m = item.GetComponent<Renderer>();

            if (m != null)
            {
                Bounds b = m.bounds;
                if (pMax.Equals(Vector3.zero) && pMin.Equals(Vector3.zero))
                {
                    pMax = b.max;
                    pMin = b.min;
                }

                if (b.max.x > pMax.x)
                {
                    pMax.x = b.max.x;
                }

                if (b.max.y > pMax.y)
                {
                    pMax.y = b.max.y;
                }
                if (b.max.z > pMax.z)
                {
                    pMax.z = b.max.z;
                }
                if (b.min.x < pMin.x)
                {
                    pMin.x = b.min.x;
                }

                if (b.min.y < pMin.y)
                {
                    pMin.y = b.min.y;
                }
                if (b.min.z < pMin.z)
                {
                    pMin.z = b.min.z;
                }
            }
            RecursivelyCalcBounds(item, ref pMax, ref pMin);
        }
    }

}