1\直线段的裁剪算法Cohen-Sutherland 2\二次、三次Bezier曲线，二次、三次均匀B样条曲线(过首末顶点)(不会抖动)-1 \ line of the cutting algorithm Cohen-Sutherland 2 \ Second, Bezier curves, second, third uniform B-spline curves (after the end of the first peak)