模块化设计，类的设计清晰，运用openGL绘制地形DEM数据，性能较好-modular design, the design category clear, use openGL DEM terrain mapping data, better performance

模块化设计，类的设计清晰，运用openGL绘制地形DEM数据，性能较好-modular design, the design category clear, use openGL DEM terrain mapping data, better performance

一个简单的绘制DEM晕渲图的程序，输入文件为国家标准的.dem文件，输出文件为位图文件-Draw a simple DEM shading procedures, the input file for the national standards. Dem file, output file for the bitmap file