Opengl Pentagram

1: #include <GL/glut.h>
2: #include <stdlib.h>
3:
4:
5: void display(void)
6: {
7: glClear(GL_COLOR_BUFFER_BIT); //flush gl
8: glColor3f(1.0, 0.0, 0.0); //red line color
9:
10: //outer pentagram, clockwise
11: glBegin(GL_LINE_LOOP);
12: glVertex2i(20,80);
13: glVertex2i(70,120);
14: glVertex2i(120,80);
15: glVertex2i(100,20);
16: glVertex2i(40,20);
17: glEnd();
18:
19: //inner pentagram
20: glBegin(GL_LINE_LOOP);
21: glVertex2i(70,100);
22: glVertex2i(90,40);
23: glVertex2i(40,70);
24: glVertex2i(100,70);
25: glVertex2i(50,40);
26: glEnd();
27:
28: //connectors
29: glBegin(GL_LINES);
30: //north
31: glVertex2i(70,120);
32: glVertex2i(70,100);
33: //north-east
34: glVertex2i(120,80);
35: glVertex2i(100,70);
36: //south-east
37: glVertex2i(100,20);
38: glVertex2i(90,40);
39: //south-west
40: glVertex2i(40,20);
41: glVertex2i(50,40);
42: //north-west
43: glVertex2i(20,80);
44: glVertex2i(40,70);
45: glEnd();
46:
47: glFlush(); //force immidiate display
48: }
49:
50: int main(int argc,char *argv[])
51: {
52: glutInit(&argc,argv); //prepare glut
53: glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); //set the display m
54: glutInitWindowSize (500, 500); //the size of the program windo
55: glutInitWindowPosition (100, 100); //initial position for the wind
56: glutCreateWindow ("points and lines"); //create window with a title
57:
58: glClearColor(255,255,255,0.0); //background color
59: glMatrixMode (GL_PROJECTION); //2d envyronment
60: gluOrtho2D (0.0, 200.0, 0.0, 150.0); //matrix dimensions
61:
62: glutDisplayFunc(display); //show thee actual program
63: glutMainLoop();
64:
65: return EXIT_SUCCESS; //exit the program
66: }
67: