protected override void UpdateShape(GameObject root)
        {
            Fix64 r = CalculateRadius();

            if (r > Fix64.zero)
            {
                Fix64Vec3 center = Fix64Vec3.zero;

                if (gameObject != root)
                {
                    center = _pTransform.localPosition;
                }

                Parallel3D.UpdateSphere(_shape, _fixture, r, center);
            }
        }