发现贴图
http://www.nvidia.com/object/real-time-normal-map-dxt-compression.html
http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-13-normal-mapping/
高光贴图
http://www.rastertek.com/dx10tut21.html
原文：http://www.cnblogs.com/lilei9110/p/6560417.html