笔者采用Visual C++6.0开发图形数据支持系统，其中的难点正在于理解坐标系统的含义、各种映射模式的意义以及与逻辑坐标的转换。-I used Visual C++ 6.0 data to support the development of graphics systems, the difficulty is in understanding the meaning of coordinate system, the significance of a variety of mappin