   Geometry Clipmaps
  Hi!I'm atm trying to implement The GPU-based geo-clipmaps from this article:http://http.developer.nvidia.com/GPUGems2/gpugems2_chapter02.htmli got all the buffers+indizes and now my question:why do they use this L-shaped region instead of making the mx3 part another mxm part??and how do u know on which side the L-shaped region has to be while moving (so when to change?)   