《图形学》实验四：中点Bresenham算法画直线
开发环境：
VC++6.0，OpenGL
实验内容：
使用中点Bresenham算法画直线。
实验结果：
代码：
1 //中点Bresenham算法生成直线
2 #include <gl/glut.h>
3 #include <math.h>
4
5 #define WIDTH 500 //窗口宽度
6 #define HEIGHT 500 //窗口高度
7 #define DRAWLINE1 MidpointBresenham(100,200,200,100); //画直线
8 #define DRAWLINE2 MidpointBresenham(200,100,450,400); //画直线
9
10 #pragma comment(linker, "/subsystem:\"windows\" /entry:\"mainCRTStartup\"") //取消控制台
11
12 void Init() //初始化
13 {
14 glClearColor(1.0f,1.0f,1.0f,1.0f); //设置背景颜色，完全不透明
15 glColor3f(1.0f,0.0f,0.0f); //设置画笔颜色
16
17 glMatrixMode(GL_PROJECTION); //设置投影
18 gluOrtho2D(0.0, WIDTH, 0.0, HEIGHT); //设置投影区域
19 }
20
21 void MidpointBresenham(int x0,int y0,int x1,int y1) //中点Bresenham算法画线
22 {
23 int dx,dy,d,UpIncre,DownIncre,x,y;
24 if(x0>x1){
25 x=x1;x1=x0;x0=x;
26 y=y1;y1=y0;y0=y;
27 }
28 x = x0,y = y0;
29 dx = x1-x0;
30 dy = y1-y0;
31 if(dy>0&&dy<=dx){ //0<k<=1
32 d = dx-2*dy;
33 UpIncre = 2*dx-2*dy;
34 DownIncre = -2*dy;
35 while(x<=x1){
36 glBegin(GL_POINTS);
37 glVertex2i(x,y);
38 glEnd();
39 x++;
40 if(d<0){
41 y++;
42 d+=UpIncre;
43 }
44 else
45 d+=DownIncre;
46 }
47 }
48 else if((dy>=(-dx))&&dy<=0) //-1<=k<=0
49 {
50 d=dx-2*dy;
51 UpIncre=-2*dy;
52 DownIncre=-2*dx-2*dy;
53 while(x<=x1)
54 {
55 glBegin(GL_POINTS);
56 glVertex2i(x,y);
57 glEnd();
58 x++;
59 if(d>0)
60 {
61 y--;
62 d+=DownIncre;
63 }
64 else d+=UpIncre;
65 }
66 }
67 else if(dy<(-dx)) //k<-1
68 {
69 d=-dy-2*dx;
70 UpIncre=2*dx+2*dy;
71 DownIncre=2*dx;
72 while(y>=y1)
73 {
74 glBegin(GL_POINTS);
75 glVertex2i(x,y);
76 glEnd();
77 y--;
78 if(d<0)
79 {
80 x++;
81 d-=UpIncre;
82 }
83 else d-=DownIncre;
84 }
85 }
86
87 else //k>1和k不存在
88 {
89 d=dy-2*dx;
90 UpIncre=2*dy-2*dx;
91 DownIncre=-2*dx;
92 while(y<=y1)
93 {
94 glBegin(GL_POINTS);
95 glVertex2i(x,y);
96 glEnd();
97 y++;
98 if(d<0)
99 {
100 x++;
101 d+=UpIncre;
102 }
103 else d+=DownIncre;
104 }
105 }
106 }
107
108 void Display() //显示函数
109 {
110 glClear(GL_COLOR_BUFFER_BIT); //清空颜色堆栈
111
112 DRAWLINE1 //画直线
113 DRAWLINE2 //画直线
114
115 glFlush(); //清空缓冲区指令
116 }
117
118 int main(int argc,char** argv)
119 {
120 glutInit(&argc,argv);
121 glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); //初始化显示模式
122 glutInitWindowSize(WIDTH,HEIGHT); //设置窗口尺寸
123 glutInitWindowPosition(200,100); //设置窗口位置
124 glutCreateWindow("画直线"); //创建窗口
125
126 glutDisplayFunc(Display); //注册显示函数
127 Init(); //初始化
128 glutMainLoop(); //进入程序循环
129 return 0;
130 }
Freecode : www.cnblogs.com/yym2013
