#include <stdio.h>
#include <windows.h>
#include <GL/GL.h>
#include <GL/glut.h>

#define WinWidth 640
#define WinHeight 480

const int MAX_POINTS = 20 ;
int Npoints = 0 ;
int Points[MAX_POINTS][2] ;

void myInit(void)
{
	glClearColor(1.0,1.0,1.0,0.0) ;
	glColor3f(0.0, 0.0, 0.0) ;
	glPointSize(4.0) ;
	glMatrixMode(GL_PROJECTION) ;
	glLoadIdentity() ;
	gluOrtho2D(0.0, 640.0, 0.0, 480.0) ;
}

void myMouse(int button, int state, int x, int y)
{
	if( button == GLUT_LEFT_BUTTON && state == GLUT_DOWN )
	{
		if( Npoints != MAX_POINTS )
		{
			Points[Npoints][0] = x ;
			Points[Npoints][1] = WinHeight - y ;
			Npoints++ ;
			printf("x = %d, y = %d\n", x,y) ;
		}
		else printf("Number of Points Exceeded\n") ;
	}
	// Tell the system to redraw the window
	glutPostRedisplay() ;
}

// The function that draws everything
void myDisplay(void) 
{
	glClear(GL_COLOR_BUFFER_BIT) ;
	glBegin(GL_POINTS) ;
	glVertex2i(100,50) ;
	glVertex2i(100,130) ;
	glVertex2i(150,130) ;
	int i ;
	for(i = 0; i < Npoints ; i++ )
		glVertex2i(Points[i][0],Points[i][1]) ;
	glEnd() ;
	// Swap the front and the back buffers
	glutSwapBuffers() ;
}

void main(int argc, char **argv)
{
	glutInit(&argc, argv) ;
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB) ;
//	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB) ;
	glutInitWindowSize(WinWidth, WinHeight) ;
	glutInitWindowPosition(100,150) ;
	glutCreateWindow("my first attempt") ;
	glutDisplayFunc(myDisplay) ;
	glutMouseFunc(myMouse) ;
	myInit() ;
	glutMainLoop() ;
}