OpenGL画圆
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 }
