3D字体演示代码，对初学者很有用，可以很详细的熟悉3D字体的绘制流程-3D fonts demo code, useful for beginners can be a very detailed drawing process are familiar with 3D fonts

使用OPENGL形成管道的程序,可用DXF文件转换为三维管线-Pipe forming process, can be converted to 3D pipeline DXF file