OpenGL编程指南：第五版：掌握各种曲线风格的绘制技巧

>       1. #include <vgl.h>

>  
>       2. //宏定义;当定义的宏不能用一行表达完整时，可以用"\"表示下一行继续
>  
>       3. #define drawOneLine(x1,y1,x2,y2) \
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>       4.              glBegin(GL_LINES);\
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>       5.              glVertex2f((x1),(y1));\
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>       6.              glVertex2f((x2),(y2));\
>  
>       7.              glEnd();
>  
>       8.  
>  
>       9. void init(void)
>  
>       10. {
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>       11.     glClearColor(0.0,0.0,0.0,0.0);
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>       12.     glShadeModel(GL_FLAT);
>  
>       13. }
>  
>       14. void display(void)
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>       15. {
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>       16.     i