1.1实现绘制Bresenham直线

运用Bresenham算法，通过点绘制实现直线。

1.2实现种子填充算法

运用4连通种子填充算法，实现填充矩形的颜色填充和矩形框内的颜色填充。

1.3实现几何变换

运用glRotated、glTranslated、glScaled实现几何图像的旋转、平移、放大、缩小。

1.4实现窗口裁剪

通过Cohen_Sutherland、Sutherland_Hodgman实现线段裁剪和多边形裁剪。

1.5实现绘制曲线

通过Bezier算法和三次B样条算法实现绘制曲线。

1.6画图

实现画直线，闭合多边形，填充多边形。

1.7清屏

清除控制台和颜色缓冲。

-Draw a straight line using Bresenham 1.1 implementation Bresenham algorithm, draw a straight line through the points. 1.2 The seed filling algorithm uses four connectivity seed filling algorithm, color filled rectangle of color fill and filled rectangle. 1.3 Geometric transformation using glRotated, glTranslated, glScaled achieve geometric image rotation, translation, zoom. 1.4 realized by cutting a window Cohen_Sutherland, Sutherland_Hodgman achieve line cutting and polygon clipping. 1.5 achieve plotted achieve Bezier curve drawing algorithm and cubic B-spline algorithm. 1.6 Drawing realize painting line, closed polygons, filled polygons. 1.7 console and clear the screen to clear the color buffer.