// Computer Graphics - Amir Hesami
//lines.cpp

#include <GL/glut.h>

#pragma comment(lib, "opengl32.lib")  // Link OpenGL32.lib
#pragma comment(lib, "glu32.lib")	  // Link Glu32.lib
#pragma comment(lib, "glut32.lib")    // Link Glut32.lib
#pragma comment(linker, "/entry:\"mainCRTStartup\"" )  // set the entry point to be main()
#pragma comment(linker, "/subsystem:\"Windows\"" )  // set the entry point to be main()

void display(void);
void init(void);

int main(int argc, char** argv)
{
	glutInit(&argc, argv);// initialise glut system
	glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB);//set the display mode
	glutInitWindowSize(500, 500);// set window size
	glutInitWindowPosition(100,100);// set window position
	glutCreateWindow("LINES");// create a window with a certain name
	glutDisplayFunc(display); //calling the drawing function
	init();
	glutMainLoop();
	return 0;
}

void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT);//clear buffers

	glColor3f(1.0, 0.0, 0.0);
	glBegin(GL_LINES);
	//line 1
		glVertex2f(0.25, 0.25);
		glVertex2f(0.75, 0.25);

	//line 2
		glVertex2f(0.75, 0.25);
		glVertex2f(0.75, 0.75);

    //line 3
		glVertex2f(0.75, 0.75);
        glVertex2f(0.25, 0.75);

    //line 4
		glVertex2f(0.25, 0.75);
        glVertex2f(0.25, 0.25);
   	glEnd();

	glFlush();
}

void init(void)
{
	glClearColor(1.0, 1.0, 1.0, 1.0);//Set window background color

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}