protected override void UpdateShape(GameObject root)
        {
            Fix64Vec3 s = CalculateSize();

            if (s == Fix64Vec3.zero)
            {
                return;
            }

            if (s == _currentSize)
            {
                return;
            }

            Fix64Vec3 scale = s / _currentSize;

            _currentSize = s;

            Parallel3D.UpdateMesh(_shape, _fixture, scale);
        }