中点画圆
1 #include<gl/glut.h>
2
3
4 void MidPointCirle(int r)
5 {
6 int x,y;
7 float d;
8 x=0;y=r;d=1.25-r;
9 glColor3f(1.0f,1.0f,1.0f);
10 glVertex2i(x,y);
11 while(x<=y)
12 {
13 if(d<0)
14 d+=2*x+3;
15 else
16 {
17 d+=2*(x-y)+5;
18 y--;
19 }
20 x++;
21 glColor3f(1.0f,1.0f,1.0f);
22 glVertex2i(x+125,y+125);
23 glColor3f(1.0f,1.0f,1.0f);
24 glVertex2i(x+125,-y+125);
25 glColor3f(1.0f,1.0f,1.0f);
26 glVertex2i(-x+125,y+125);
27 glColor3f(1.0f,1.0f,1.0f);
28 glVertex2i(-x+125,-y+125);
29 glColor3f(1.0f,1.0f,1.0f);
30 glVertex2i(y+125,x+125);
31 glColor3f(1.0f,1.0f,1.0f);
32 glVertex2i(y+125,-x+125);
33 glColor3f(1.0f,1.0f,1.0f);
34 glVertex2i(-y+125,x+125);
35 glColor3f(1.0f,1.0f,1.0f);
36 glVertex2i(-y+125,-x+125);
37 }
38 glFlush();
39
40 }
41 void ChangeSize(GLsizei w,GLsizei h)
42 {
43 if(h==0)
44 h=1;
45 glMatrixMode(GL_PROJECTION);
46 glLoadIdentity();
47 if(w<=h)
48 glOrtho(0.0f,250.0f,0.0f,250.0f*h/w,1.0f,-1.0f);
49 else
50 glOrtho(0.0f,250.0f*w/h,0.0f,250.0f,1.0f,-1.0f);
51 glMatrixMode(GL_MODELVIEW);
52 glLoadIdentity();
53 }
54
55 void myDisplay(void)
56 {
57 glClear(GL_COLOR_BUFFER_BIT);
58 glPointSize(3);
59 glBegin(GL_POINTS);
60 glVertex2i(125,125);
61 MidPointCirle(125);
62 glEnd();
63 // glDrawpixels(width,height,GL_RGBA,GL_UNSIGNED_BYTE,pixels);
64 glFlush();
65 }
66 int main(int argc,char *argv[])
67 {
68
69 glutInit(&argc,argv);
70 glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
71 glutInitWindowPosition(100,100);
72 glutInitWindowSize(500,500);
73 glutCreateWindow("圆");
74 glutDisplayFunc(*myDisplay);
75 // glutDisplayFunc(MidPointCirle);
76 glutReshapeFunc(ChangeSize);
77 glutMainLoop();
78 return 0;
79 } 多边形画圆
1 #include<gl/glut.h>
2 #include<math.h>
3 const GLfloat Pi=301415927;
4 const GLfloat R=0.5f;
5 const int n=1000;
6
7 void myDisplay(void)
8 {
9 int i;
10 glClear(GL_COLOR_BUFFER_BIT);
11 glColor3f(1.0f,1.0f,1.0f);
12 glBegin(GL_POINTS);
13 for(i=0;i<n;++i)
14 glVertex2f(R*cos(2*Pi/n*i),R*sin(2*Pi/n*i));
15 glEnd();
16
17
18 glFlush();
19 }
20 void ChangeSize(GLsizei w,GLsizei h)
21 {
22 if(h==0)
23 h=1;
24 glMatrixMode(GL_PROJECTION);
25 glLoadIdentity();
26 if(w<=h)
27 glOrtho(0.0f,250.0f,0.0f,250.0f*h/w,1.0f,-1.0f);
28 else
29 glOrtho(0.0f,250.0f*w/h,0.0f,250.0f,1.0f,-1.0f);
30 glMatrixMode(GL_MODELVIEW);
31 glLoadIdentity();
32 }
33
34
35 int main(int argc,char *argv[])
36 {
37
38 glutInit(&argc,argv);
39 glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
40 glutInitWindowPosition(100,100);
41 glutInitWindowSize(500,500);
42 glutCreateWindow("圆");
43 glutDisplayFunc(*myDisplay);
44
45 // glutReshapeFunc(ChangeSize);
46 glutMainLoop();
47 return 0;
48 }