#include <GL/glut.h>
#include <stdlib.h>


void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT);	//flush gl
	glColor3f(1.0, 0.0, 0.0);		//red line color

	//outer pentagram, clockwise
	glBegin(GL_LINE_LOOP);
		glVertex2i(20,80);
		glVertex2i(70,120);
		glVertex2i(120,80);
		glVertex2i(100,20);
		glVertex2i(40,20);	
	glEnd();
	
	//inner pentagram
	glBegin(GL_LINE_LOOP);
		glVertex2i(70,100);
		glVertex2i(90,40);
		glVertex2i(40,70);
		glVertex2i(100,70);
		glVertex2i(50,40);
	glEnd();

	//connectors
	glBegin(GL_LINES);
 	    //north
 		glVertex2i(70,120);
		glVertex2i(70,100);
		//north-east
		glVertex2i(120,80);
		glVertex2i(100,70);
		//south-east
		glVertex2i(100,20);
		glVertex2i(90,40);
		//south-west
		glVertex2i(40,20);
		glVertex2i(50,40);
		//north-west
		glVertex2i(20,80);
		glVertex2i(40,70);				
	glEnd();

	glFlush();	//force immidiate display
}

int main(int argc,char *argv[])
{
	glutInit(&argc,argv);					//prepare glut
	glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);		//set the display mode
	glutInitWindowSize (500, 500);			//the size of the program window
	glutInitWindowPosition (100, 100);		//initial position for the window
	glutCreateWindow ("points and lines");	//create window with a title
	
	glClearColor(255,255,255,0.0);  		//background color
	glMatrixMode (GL_PROJECTION);			//2d envyronment
	gluOrtho2D (0.0, 200.0, 0.0, 150.0);	//matrix dimensions
	
	glutDisplayFunc(display);				//show thee actual program
	glutMainLoop();
	
	return EXIT_SUCCESS;					//exit the program
}