隨著資訊時代的來臨，對於圖形的需要愈來愈重要。尤其近幾年來，電腦硬體計算速度加快，記憶體容量加大，以及顯示器解析度的提高，更加速了電腦圖學的發展，其應用領域包含其廣，試想在一個真實物體的圖形如何劃出好看的曲線，顯示的部位是什麼?劃在何處?顯示的大小如何?如何從真實物體的一點映射到螢幕上一點?[1] Follow the coming of computer era, the requirement of graphic is more and more important. Especially in the recent years, the calculating speed of hardware is faster, the capacity of memory is larger, and the resolution of screen is higher, accelerate the development of computer graphics in broad fields. Try to think, if you want to draw a good_looking curve for a real object, how to draw? Which part of the object to draw? Where does it suppose to be drawn? How big? How to map a point of the real object to a point on the screen?
