Depends what you mean. I think the glu function uses a simple box-map to generate the texture levels. Sure, you could probably write and optimise a quicker\better version, but glu is generally good enough.
Oh and if I think I read you correctly, your LOD level for tmapping is something you don’t have to worry about at all if you are using mip-maps (texture levels with OpenGL) - you won’t get shimmering etc. if you are using GL_LINEAR_MIPMAP_LINEAR etc.
[This message has been edited by Robbo (edited 09-02-2002).]