Texture LOD Computation
From CGAFaq
One paper work reading is MIP-Map Level Selection for Texture Mapping by Jon P. Ewins, Marcus D. Waller, Martin White, and Paul F. Lister, IEEE Transactions on Visualization and Computer Graphics, Volume 4, number 4, October 1998, 317-329. http://dx.doi.org/10.1109/2945.765326

